topic Re: Slowing DDR3 clock for i.MX6Q in i.MX Processors

Slowing DDR3 clock for i.MX6Q

frankmiller — Fri, 19 Jul 2013 16:19:09 GMT

Greetings,

We're having some trouble with a custom i.MX6Q board (based on sabreSD reference). It appears that our DDR3 is close to timing margins. I'd like to slow the DDR3 clock rate down to 396MHz. I tried plugging that value into the DDR3 programming spreadsheet and replacing the values in flash_header.S with the updated spreadsheet values. However, when u-boot comes up, its still showing 528MHz for the ddr clock. I also noticed that mx6q pll2 is set to 528MHz. Is there something else I need to do, like change pll2 somehow?

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

AnsonHuang — Sat, 20 Jul 2013 04:17:21 GMT

Hi, Frank

I think the mmdc_axi_ch0 is sourced from periph_clk, and periph_clk is from pll2 which is 528M, so to get 396MHz for DDR3, you may need to switch clock source of periph_clk from pll2 to pfd396M, you need to check the CCM for clock tree, and switch this clock before DCD table of configuring MMDC. Also, I think the DDR script for 528M an 396M is different, if it still not work, you may need to check the script. But first of all, just make the clock freq right, it must be 396M.

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Sat, 20 Jul 2013 04:38:52 GMT

Hi Huang,

Thanks for the reply.

I've already adjusted the script in flash_header.S and that did not change the clock. That's why I'm asking the question.

The real problem we're having is as follows. We have 25 boards that are using an i.MX6Q @ 1.2 GHz. Only a couple of them boot up reliably. We had built 6 boards previously using a 1 GHz i.MX6D that ran fine. Both processors are TO1.2 lots. We upgraded to the 4.0.0 release as well. We ran DDR3 stress tests on some of the boards and have discovered that there seem to be failures as the DDR3 testing gets to 528 MHz. This behavior feels like there is some issue with timing margins or something between the processor and the DDR3 memory but we have not been able to isolate it as yet. We were going to try slowing the memory down on the 25 boards to see if we get better results. Do you have any other advice? I noticed another message thread on these boards where someone else was having similar problems: Tuning DDR3 configurations on iMX6Q board This other thread was marked as "assumed answered" but it was not clear from that thread what the solution was.

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

AnsonHuang — Sat, 20 Jul 2013 08:49:15 GMT

Hi, Frank

I think we need to try 396M first. For some boards that can boot up reliably, did they run @528MHz DDR freq or 396MHz? You said that you have adjust the script to 396M, but the script did not change the clock, that is why I need you to try adding the clock change first, Setting pre_periph_clk select to from pfd396M, you may need to add one DCD item in flash_header.S, DCD(0x20c4018, 0x60324) in front of the MMDC and IOMUX settng. Then you also need to add this length to DCD length parameter. See below:

/* CCM_BASE_ADDR = 0x020C4000 */

/*DDR clk to 400MHz*/

ldr r0, =CCM_BASE_ADDR

ldr r1, =0x00060324

str r1, [r0, #0x018]

[Anson] Change this to DCD(0x20c4018, 0x60324), please check RM to see whether this 0x60324 is right to select PFD396 as pre_periph_clk's parent.

dcd_hdr: .word 0x40F003D2 /* Tag=0xD2, Len=125*8 + 4 + 4, Ver=0x40 */

write_dcd_cmd: .word 0x04EC03CC /* Tag=0xCC, Len=125*8 + 4, Param=0x04 */

[Anson]As the DCD number is increased, so upper value need to changed to be 126*8 + 4 + 4 and 126*8 + 4.

Please try it first to see whether we can make more boards boot up reliably @396M, if it helps, then we can focus on the DDR timing adjustment.

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Sat, 20 Jul 2013 23:01:23 GMT

OK, I tried to add this DCD (per the Anson comment to the beginning of my flash_header.S script. The board does not boot at all now.

Regarding the 0x60324 value, I checked the RM and the the 0x6 prefix does appear to set the pre_periph_clk to 396 MHz as you suggested. I did note however that the default value for this register is 0x22324 so your 0x60 prefix is setting different values for pre_periph_clk_sel as well as gpu2d_clk_sel, vpu_axi_clk_sel, and periph_clk2_sel? Also, the default value for this register means that 00 (528 MHz clk) is chosen for pre_periph_clk, but the explanation for bits 18-19 state that 01 should be the default value, which yields a 396 MHz clock default. Very confusing. Maybe there's something going on in the ROM here?

Couple things to note here about my flash_header.S script. We are using 4 GB of DDR3 64-bit in 8 256MB Micron devices. I had created a script for our dual core boards and things were working fine. So in this script where you see the // 396 MHz comments are the places I had to change to switch to the 396 MHz speed according to the spreadsheet. I added the line you recommended at DCD item 1. This caused me to have to renumber all the other DCD items. I also bumped up the Len part of the dcd_hdr and write_dcd_cmd labels as directed.

Here is what my flash_header.S script looks like:

#else /* i.MX6Q */

//dcd_hdr: .word 0x40a002D2 /* Tag=0xD2, Len=83*8 + 4 + 4, Ver=0x40 */

//write_dcd_cmd: .word 0x049c02CC /* Tag=0xCC, Len=83*8 + 4, Param=0x04 */

//dcd_hdr: .word 0x40c802d2 /* Tag=0xD2, Len=88*8 + 4 + 4, Ver=0x40 */

//write_dcd_cmd: .word 0x04c402cc /* Tag=0xCC, Len=88*8 + 4, Param=0x04 */

dcd_hdr: .word 0x40d002d2 /* Tag=0xD2, Len=89*8 + 4 + 4, Ver=0x40 */

write_dcd_cmd: .word 0x04cc02cc /* Tag=0xCC, Len=89*8 + 4, Param=0x04 */

/* DCD */

// <added>

// Change pre_periph_clk to pfd396M

MXC_DCD_ITEM(1, 0x020c4018, 0x00060324)

// </added>

MXC_DCD_ITEM(2, IOMUXC_BASE_ADDR + 0x798, 0x000C0000)

MXC_DCD_ITEM(3, IOMUXC_BASE_ADDR + 0x758, 0x00000000)

MXC_DCD_ITEM(4, IOMUXC_BASE_ADDR + 0x588, 0x00000030)

MXC_DCD_ITEM(5, IOMUXC_BASE_ADDR + 0x594, 0x00000030)

MXC_DCD_ITEM(6, IOMUXC_BASE_ADDR + 0x56c, 0x00000030)

MXC_DCD_ITEM(7, IOMUXC_BASE_ADDR + 0x578, 0x00000030)

MXC_DCD_ITEM(8, IOMUXC_BASE_ADDR + 0x74c, 0x00000030)

MXC_DCD_ITEM(9, IOMUXC_BASE_ADDR + 0x57c, 0x00000030)

MXC_DCD_ITEM(10, IOMUXC_BASE_ADDR + 0x58c, 0x00000000)

MXC_DCD_ITEM(11, IOMUXC_BASE_ADDR + 0x59c, 0x00000030)

MXC_DCD_ITEM(12, IOMUXC_BASE_ADDR + 0x5a0, 0x00000030)

MXC_DCD_ITEM(13, IOMUXC_BASE_ADDR + 0x78c, 0x00000030)

MXC_DCD_ITEM(14, IOMUXC_BASE_ADDR + 0x750, 0x00020000)

MXC_DCD_ITEM(15, IOMUXC_BASE_ADDR + 0x5a8, 0x00000030)

MXC_DCD_ITEM(16, IOMUXC_BASE_ADDR + 0x5b0, 0x00000030)

MXC_DCD_ITEM(17, IOMUXC_BASE_ADDR + 0x524, 0x00000030)

MXC_DCD_ITEM(18, IOMUXC_BASE_ADDR + 0x51c, 0x00000030)

MXC_DCD_ITEM(19, IOMUXC_BASE_ADDR + 0x518, 0x00000030)

MXC_DCD_ITEM(20, IOMUXC_BASE_ADDR + 0x50c, 0x00000030)

MXC_DCD_ITEM(21, IOMUXC_BASE_ADDR + 0x5b8, 0x00000030)

MXC_DCD_ITEM(22, IOMUXC_BASE_ADDR + 0x5c0, 0x00000030)

MXC_DCD_ITEM(23, IOMUXC_BASE_ADDR + 0x774, 0x00020000)

MXC_DCD_ITEM(24, IOMUXC_BASE_ADDR + 0x784, 0x00000030)

MXC_DCD_ITEM(25, IOMUXC_BASE_ADDR + 0x788, 0x00000030)

MXC_DCD_ITEM(26, IOMUXC_BASE_ADDR + 0x794, 0x00000030)

MXC_DCD_ITEM(27, IOMUXC_BASE_ADDR + 0x79c, 0x00000030)

MXC_DCD_ITEM(28, IOMUXC_BASE_ADDR + 0x7a0, 0x00000030)

MXC_DCD_ITEM(29, IOMUXC_BASE_ADDR + 0x7a4, 0x00000030)

MXC_DCD_ITEM(30, IOMUXC_BASE_ADDR + 0x7a8, 0x00000030)

MXC_DCD_ITEM(31, IOMUXC_BASE_ADDR + 0x748, 0x00000030)

MXC_DCD_ITEM(32, IOMUXC_BASE_ADDR + 0x5ac, 0x00000030)

MXC_DCD_ITEM(33, IOMUXC_BASE_ADDR + 0x5b4, 0x00000030)

MXC_DCD_ITEM(34, IOMUXC_BASE_ADDR + 0x528, 0x00000030)

MXC_DCD_ITEM(35, IOMUXC_BASE_ADDR + 0x520, 0x00000030)

MXC_DCD_ITEM(36, IOMUXC_BASE_ADDR + 0x514, 0x00000030)

MXC_DCD_ITEM(37, IOMUXC_BASE_ADDR + 0x510, 0x00000030)

MXC_DCD_ITEM(38, IOMUXC_BASE_ADDR + 0x5bc, 0x00000030)

MXC_DCD_ITEM(39, IOMUXC_BASE_ADDR + 0x5c4, 0x00000030)

MXC_DCD_ITEM(40, MMDC_P0_BASE_ADDR + 0x800, 0xA1390003)

MXC_DCD_ITEM(41, MMDC_P0_BASE_ADDR + 0x80c, 0x001F001F)

MXC_DCD_ITEM(42, MMDC_P0_BASE_ADDR + 0x810, 0x001F001F)

MXC_DCD_ITEM(43, MMDC_P1_BASE_ADDR + 0x80c, 0x001F001F)

MXC_DCD_ITEM(44, MMDC_P1_BASE_ADDR + 0x810, 0x001F001F)

//MXC_DCD_ITEM(45, MMDC_P0_BASE_ADDR + 0x83c, 0x4333033F)

MXC_DCD_ITEM(45, MMDC_P0_BASE_ADDR + 0x83c, 0x43270338)

//MXC_DCD_ITEM(46, MMDC_P0_BASE_ADDR + 0x840, 0x032C031D)

MXC_DCD_ITEM(46, MMDC_P0_BASE_ADDR + 0x840, 0x03200314)

//MXC_DCD_ITEM(47, MMDC_P1_BASE_ADDR + 0x83c, 0x43200332)

MXC_DCD_ITEM(47, MMDC_P1_BASE_ADDR + 0x83c, 0x431a032f)

//MXC_DCD_ITEM(48, MMDC_P1_BASE_ADDR + 0x840, 0x031A026A)

MXC_DCD_ITEM(48, MMDC_P1_BASE_ADDR + 0x840, 0x03200263)

//MXC_DCD_ITEM(49, MMDC_P0_BASE_ADDR + 0x848, 0x4D464746)

MXC_DCD_ITEM(49, MMDC_P0_BASE_ADDR + 0x848, 0x4b434748)

//MXC_DCD_ITEM(50, MMDC_P1_BASE_ADDR + 0x848, 0x47453F4D)

MXC_DCD_ITEM(50, MMDC_P1_BASE_ADDR + 0x848, 0x4445404c)

//MXC_DCD_ITEM(51, MMDC_P0_BASE_ADDR + 0x850, 0x3E434440)

MXC_DCD_ITEM(51, MMDC_P0_BASE_ADDR + 0x850, 0x38444542)

//MXC_DCD_ITEM(52, MMDC_P1_BASE_ADDR + 0x850, 0x47384839)

MXC_DCD_ITEM(52, MMDC_P1_BASE_ADDR + 0x850, 0x4935493a)

MXC_DCD_ITEM(53, MMDC_P0_BASE_ADDR + 0x81c, 0x33333333)

MXC_DCD_ITEM(54, MMDC_P0_BASE_ADDR + 0x820, 0x33333333)

MXC_DCD_ITEM(55, MMDC_P0_BASE_ADDR + 0x824, 0x33333333)

MXC_DCD_ITEM(56, MMDC_P0_BASE_ADDR + 0x828, 0x33333333)

MXC_DCD_ITEM(57, MMDC_P1_BASE_ADDR + 0x81c, 0x33333333)

MXC_DCD_ITEM(58, MMDC_P1_BASE_ADDR + 0x820, 0x33333333)

MXC_DCD_ITEM(59, MMDC_P1_BASE_ADDR + 0x824, 0x33333333)

MXC_DCD_ITEM(60, MMDC_P1_BASE_ADDR + 0x828, 0x33333333)

MXC_DCD_ITEM(61, MMDC_P0_BASE_ADDR + 0x8b8, 0x00000800)

MXC_DCD_ITEM(62, MMDC_P1_BASE_ADDR + 0x8b8, 0x00000800)

//MXC_DCD_ITEM(63, MMDC_P0_BASE_ADDR + 0x004, 0x00020036)

MXC_DCD_ITEM(63, MMDC_P0_BASE_ADDR + 0x004, 0x00020024) // 396 MHz

//MXC_DCD_ITEM(64, MMDC_P0_BASE_ADDR + 0x008, 0x09444040)

MXC_DCD_ITEM(64, MMDC_P0_BASE_ADDR + 0x008, 0x00444040) // 396 MHz

//MXC_DCD_ITEM(65, MMDC_P0_BASE_ADDR + 0x00c, 0x555A7975)

MXC_DCD_ITEM(65, MMDC_P0_BASE_ADDR + 0x00c, 0x3f435313) // 396 MHz

//MXC_DCD_ITEM(66, MMDC_P0_BASE_ADDR + 0x010, 0xFF538F64)

MXC_DCD_ITEM(66, MMDC_P0_BASE_ADDR + 0x010, 0xb66e8b64) // 396 MHz

//MXC_DCD_ITEM(67, MMDC_P0_BASE_ADDR + 0x014, 0x01FF00DB)

MXC_DCD_ITEM(67, MMDC_P0_BASE_ADDR + 0x014, 0x01ff0092) // 396 MHz

//MXC_DCD_ITEM(68, MMDC_P0_BASE_ADDR + 0x018, 0x00001740)

//MXC_DCD_ITEM(68, MMDC_P0_BASE_ADDR + 0x018, 0x000f11c0)

MXC_DCD_ITEM(68, MMDC_P0_BASE_ADDR + 0x018, 0x00001740) // 396 MHz

MXC_DCD_ITEM(69, MMDC_P0_BASE_ADDR + 0x01c, 0x00008000)

MXC_DCD_ITEM(70, MMDC_P0_BASE_ADDR + 0x02c, 0x000026D2)

//MXC_DCD_ITEM(71, MMDC_P0_BASE_ADDR + 0x030, 0x005A1023)

MXC_DCD_ITEM(71, MMDC_P0_BASE_ADDR + 0x030, 0x00431023) // 396 MHz

//MXC_DCD_ITEM(72, MMDC_P0_BASE_ADDR + 0x040, 0x00000027)

//MXC_DCD_ITEM(72, MMDC_P0_BASE_ADDR + 0x040, 0x0000003f)

MXC_DCD_ITEM(72, MMDC_P0_BASE_ADDR + 0x040, 0x00000047) // 396 MHz

//MXC_DCD_ITEM(73, MMDC_P0_BASE_ADDR + 0x000, 0x831A0000)

MXC_DCD_ITEM(73, MMDC_P0_BASE_ADDR + 0x000, 0xc41a0000)

MXC_DCD_ITEM(74, MMDC_P0_BASE_ADDR + 0x01c, 0x04088032)

MXC_DCD_ITEM(75, MMDC_P0_BASE_ADDR + 0x01c, 0x00008033)

MXC_DCD_ITEM(76, MMDC_P0_BASE_ADDR + 0x01c, 0x00048031)

//MXC_DCD_ITEM(77, MMDC_P0_BASE_ADDR + 0x01c, 0x09408030)

MXC_DCD_ITEM(77, MMDC_P0_BASE_ADDR + 0x01c, 0x05208030) // 396 MHz

MXC_DCD_ITEM(78, MMDC_P0_BASE_ADDR + 0x01c, 0x04008040)

// <added>

MXC_DCD_ITEM(79, MMDC_P0_BASE_ADDR + 0x01c, 0x0408803a)

MXC_DCD_ITEM(80, MMDC_P0_BASE_ADDR + 0x01c, 0x0000803b)

MXC_DCD_ITEM(81, MMDC_P0_BASE_ADDR + 0x01c, 0x00048039)

//MXC_DCD_ITEM(82, MMDC_P0_BASE_ADDR + 0x01c, 0x09408038)

MXC_DCD_ITEM(82, MMDC_P0_BASE_ADDR + 0x01c, 0x05208038) // 396 MHz

MXC_DCD_ITEM(83, MMDC_P0_BASE_ADDR + 0x01c, 0x04008048)

// </added>

MXC_DCD_ITEM(84, MMDC_P0_BASE_ADDR + 0x020, 0x00005800)

MXC_DCD_ITEM(85, MMDC_P0_BASE_ADDR + 0x818, 0x00011117)

MXC_DCD_ITEM(86, MMDC_P1_BASE_ADDR + 0x818, 0x00011117)

//MXC_DCD_ITEM(87, MMDC_P0_BASE_ADDR + 0x004, 0x00025576)

MXC_DCD_ITEM(87, MMDC_P0_BASE_ADDR + 0x004, 0x00025564) // 396 MHz

MXC_DCD_ITEM(88, MMDC_P0_BASE_ADDR + 0x404, 0x00011006)

MXC_DCD_ITEM(89, MMDC_P0_BASE_ADDR + 0x01c, 0x00000000)

#endif

Re: Slowing DDR3 clock for i.MX6Q

AnsonHuang — Mon, 22 Jul 2013 10:35:48 GMT

Hi, Frank

below(sorry I do NOT know how to attach a file) is the flash_header.S of 400MHz DDR using plugin mode, this is a debug version when I was trying 400MHz for DDR3, you can have a reference, but I am not sure whether it works on your platform.

#include <config.h>

#include <asm/arch/mx6.h>

#ifdef CONFIG_FLASH_HEADER

#ifndef CONFIG_FLASH_HEADER_OFFSET

# error "Must define the offset of flash header"

#endif

.section ".text.flasheader", "x"

b _start

.org CONFIG_FLASH_HEADER_OFFSET

/* First IVT to copy the plugin that initializes the system into OCRAM */

ivt_header: .long 0x402000D1 /*Tag=0xD1, Len=0x0020, Ver=0x40 */

app_code_jump_v: .long 0x00907458 /* Plugin entry point, address after the second IVT table */

reserv1: .long 0x0

dcd_ptr: .long 0x0

boot_data_ptr: .long 0x00907420

self_ptr: .long 0x00907400

app_code_csf: .long 0x0

reserv2: .long 0x0

boot_data: .long 0x00907000

image_len: .long 16*1024 /* plugin can be upto 16KB in size */

plugin: .long 0x1 /* Enable plugin flag */

/* Second IVT to give entry point into the bootloader copied to DDR */

ivt2_header: .long 0x402000D1 /*Tag=0xD1, Len=0x0020, Ver=0x40 */

app2_code_jump_v: .long _start /* Entry point for uboot */

reserv3: .long 0x0

dcd2_ptr: .long 0x0

boot_data2_ptr: .long boot_data2

self_ptr2: .long ivt2_header

app_code_csf2: .long 0x0

reserv4: .long 0x0

boot_data2: .long TEXT_BASE

image_len2: .long _end_of_copy - TEXT_BASE + CONFIG_FLASH_HEADER_OFFSET

plugin2: .long 0x0

/* Here starts the plugin code */

plugin_start:

/* Save the return address and the function arguments */

push {r0-r4, lr}

* Note: The DDR settings provided below are specific to Freescale development boards and are the latest settings at the time of release.

* However, it is recommended to contact your Freescale representative in case there are any improvements to these settings.

/* Init the DDR according the init script */

ldr r0, =CCM_BASE_ADDR

/* select 400MHz for pre_periph_clk_sel */

ldr r1, =0x00060324

str r1, [r0,#0x18]

/* 64-bit DDR3 */

/* IOMUX setting */

ldr r0, =IOMUXC_BASE_ADDR

mov r1, #0x30

str r1, [r0,#0x5a8]

str r1, [r0,#0x5b0]

str r1, [r0,#0x524]

str r1, [r0,#0x51c]

str r1, [r0,#0x518]

str r1, [r0,#0x50c]

str r1, [r0,#0x5b8]

str r1, [r0,#0x5c0]

ldr r1, =0x00020030

str r1, [r0,#0x5ac]

str r1, [r0,#0x5b4]

str r1, [r0,#0x528]

str r1, [r0,#0x520]

str r1, [r0,#0x514]

str r1, [r0,#0x510]

str r1, [r0,#0x5bc]

str r1, [r0,#0x5c4]

str r1, [r0,#0x56c]

str r1, [r0,#0x578]

str r1, [r0,#0x588]

str r1, [r0,#0x594]

str r1, [r0,#0x57c]

ldr r1, =0x00003000

str r1, [r0,#0x590]

str r1, [r0,#0x598]

mov r1, #0x00

str r1, [r0,#0x58c]

ldr r1, =0x00003030

str r1, [r0,#0x59c]

str r1, [r0,#0x5a0]

ldr r1, =0x00000030

str r1, [r0,#0x784]

str r1, [r0,#0x788]

str r1, [r0,#0x794]

str r1, [r0,#0x79c]

str r1, [r0,#0x7a0]

str r1, [r0,#0x7a4]

str r1, [r0,#0x7a8]

str r1, [r0,#0x748]

str r1, [r0,#0x74c]

mov r1, #0x00020000

str r1, [r0,#0x750]

mov r1, #0x00000000

str r1, [r0,#0x758]

mov r1, #0x00020000

str r1, [r0,#0x774]

mov r1, #0x30

str r1, [r0,#0x78c]

mov r1, #0x000c0000

str r1, [r0,#0x798]

/* Initialize 2GB DDR3 - Micron MT41J128M */

ldr r0, =MMDC_P0_BASE_ADDR

ldr r2, =MMDC_P1_BASE_ADDR

ldr r1, =0x02020207

str r1, [r0,#0x83c]

ldr r1, =0x02020201

str r1, [r0,#0x840]

ldr r1, =0x02020207

str r1, [r2,#0x83c]

ldr r1, =0x02150203

str r1, [r2,#0x840]

ldr r1, =0x3E35353B

str r1, [r0,#0x848]

ldr r1, =0x3A393541

str r1, [r2,#0x848]

ldr r1, =0x41424744

str r1, [r0,#0x850]

ldr r1, =0x4937483B

str r1, [r2,#0x850]

ldr r1, =0x33333333

str r1, [r0,#0x81c]

str r1, [r0,#0x820]

str r1, [r0,#0x824]

str r1, [r0,#0x828]

str r1, [r2,#0x81c]

str r1, [r2,#0x820]

str r1, [r2,#0x824]

str r1, [r2,#0x828]

ldr r1, =0x00081740

str r1, [r0,#0x18]

ldr r1, =0x00008000

str r1, [r0,#0x1c]

ldr r1, =0x555b99a4

str r1, [r0,#0x0c]

ldr r1, =0xfe730e64

str r1, [r0,#0x10]

ldr r1, =0x01ff00db

str r1, [r0,#0x14]

ldr r1, =0x000026d2

str r1, [r0,#0x2c]

ldr r1, =0x005b0e21

str r1, [r0,#0x30]

ldr r1, =0x1b334000

str r1, [r0,#0x08]

ldr r1, =0x0003002d

str r1, [r0,#0x04]

ldr r1, =0x00000027

str r1, [r0,#0x40]

ldr r1, =0xc31a0000

str r1, [r0,#0x00]

ldr r1, =0x00000800

str r1, [r0,#0x8b8]

ldr r1, =0x04088032

str r1, [r0,#0x1c]

ldr r1, =0x0408803a

str r1, [r0,#0x1c]

ldr r1, =0x00008033

str r1, [r0,#0x1c]

ldr r1, =0x0000803b

str r1, [r0,#0x1c]

ldr r1, =0x00428031

str r1, [r0,#0x1c]

ldr r1, =0x00428039

str r1, [r0,#0x1c]

ldr r1, =0x09308030

str r1, [r0,#0x1c]

ldr r1, =0x09308038

str r1, [r0,#0x1c]

ldr r1, =0x04008040

str r1, [r0,#0x1c]

ldr r1, =0x04008048

str r1, [r0,#0x1c]

ldr r1, =0xa5380003

str r1, [r0,#0x800]

ldr r1, =0x00005800

str r1, [r0,#0x20]

ldr r1, =0x00022221

str r1, [r0,#0x818]

ldr r1, =0x00022221

str r1, [r2,#0x818]

ldr r1, =0x00000000

str r1, [r0,#0x1c]

/********************

The following is to fill in those arguments for this ROM function

pu_irom_hwcnfg_setup(void **start, size_t *bytes, const void *boot_data)

This function is used to copy data from the storage media into DDR.

start - Initial (possibly partial) image load address on entry. Final image load address on exit.

bytes - Initial (possibly partial) image size on entry. Final image size on exit.

boot_data - Initial @ref ivt Boot Data load address.

adr r0, DDR_DEST_ADDR

adr r1, COPY_SIZE

adr r2, BOOT_DATA

* check the _pu_irom_api_table for the address

before_calling_rom___pu_irom_hwcnfg_setup:

mov r4, #0x2000

add r4, r4, #0xed

blx r4 /* This address might change in future ROM versions */

after_calling_rom___pu_irom_hwcnfg_setup:

/* To return to ROM from plugin, we need to fill in these argument.

* Here is what need to do:

* Need to construct the paramters for this function before return to ROM:

* plugin_download(void **start, size_t *bytes, UINT32 *ivt_offset)

pop {r0-r4, lr}

ldr r5, DDR_DEST_ADDR

str r5, [r0]

ldr r5, COPY_SIZE

str r5, [r1]

mov r5, #0x400 /* Point to the second IVT table at offset 0x42C */

add r5, r5, #0x2C

str r5, [r2]

mov r0, #1

bx lr /* return back to ROM code */

DDR_DEST_ADDR: .word TEXT_BASE

COPY_SIZE: .word _end_of_copy - TEXT_BASE + CONFIG_FLASH_HEADER_OFFSET

BOOT_DATA: .word TEXT_BASE

.word _end_of_copy - TEXT_BASE + CONFIG_FLASH_HEADER_OFFSET

.word 0

#endif

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Mon, 22 Jul 2013 17:33:54 GMT

Hi Huang,

I'm confused. The only difference between this code and what you posted before is the expanded headers. I don't think those are the problem. You are still using the same code to redirect the periph clk which I alread told you doesn't work. Can you comment on the items I discussed about the use of 0x60324 to accomplish that?

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

byungchul — Tue, 23 Jul 2013 02:15:59 GMT

Also, I was trying to same ploblems.

Results are 480Mhz operations good, but 400Mhz was failed.

<u-boot>

528Mhz --> 480Mhz --> 400Mhz step operation is success, using the clk command in the u-boot.

It's not working problems(400Mhz) is thought to be caused by something happens in the BOOTROM.

# 480MHZ

#CBCDR, 480MHz
MXC_DCD_ITEM(39, CCM_BASE_ADDR + 0x14, 0x02018d00)
#CBCMR, 480MHz
MXC_DCD_ITEM(40, CCM_BASE_ADDR + 0x18, 0x00020324)

MXC_DCD_ITEM(41, MMDC_P0_BASE_ADDR + 0x800, 0xA1390003)

MXC_DCD_ITEM(42, MMDC_P0_BASE_ADDR + 0x80c, 0x001F001F)
MXC_DCD_ITEM(43, MMDC_P0_BASE_ADDR + 0x810, 0x001F001F)
MXC_DCD_ITEM(44, MMDC_P1_BASE_ADDR + 0x80c, 0x001F001F)
MXC_DCD_ITEM(45, MMDC_P1_BASE_ADDR + 0x810, 0x001F001F)

MXC_DCD_ITEM(46, MMDC_P0_BASE_ADDR + 0x83c, 0x4333033F)
MXC_DCD_ITEM(47, MMDC_P0_BASE_ADDR + 0x840, 0x032C031D)
MXC_DCD_ITEM(48, MMDC_P1_BASE_ADDR + 0x83c, 0x43200332)
MXC_DCD_ITEM(49, MMDC_P1_BASE_ADDR + 0x840, 0x031A026A)
MXC_DCD_ITEM(50, MMDC_P0_BASE_ADDR + 0x848, 0x4D464746)
MXC_DCD_ITEM(51, MMDC_P1_BASE_ADDR + 0x848, 0x47453F4D)
MXC_DCD_ITEM(52, MMDC_P0_BASE_ADDR + 0x850, 0x3E434440)
MXC_DCD_ITEM(53, MMDC_P1_BASE_ADDR + 0x850, 0x47384839)

MXC_DCD_ITEM(54, MMDC_P0_BASE_ADDR + 0x81c, 0x33333333)
MXC_DCD_ITEM(55, MMDC_P0_BASE_ADDR + 0x820, 0x33333333)
MXC_DCD_ITEM(56, MMDC_P0_BASE_ADDR + 0x824, 0x33333333)
MXC_DCD_ITEM(57, MMDC_P0_BASE_ADDR + 0x828, 0x33333333)
MXC_DCD_ITEM(58, MMDC_P1_BASE_ADDR + 0x81c, 0x33333333)
MXC_DCD_ITEM(59, MMDC_P1_BASE_ADDR + 0x820, 0x33333333)
MXC_DCD_ITEM(60, MMDC_P1_BASE_ADDR + 0x824, 0x33333333)
MXC_DCD_ITEM(61, MMDC_P1_BASE_ADDR + 0x828, 0x33333333)

MXC_DCD_ITEM(62, MMDC_P0_BASE_ADDR + 0x8b8, 0x00000800)
MXC_DCD_ITEM(63, MMDC_P1_BASE_ADDR + 0x8b8, 0x00000800)

#MMDC init
MXC_DCD_ITEM(64, MMDC_P0_BASE_ADDR + 0x004, 0x0002002D)
MXC_DCD_ITEM(65, MMDC_P0_BASE_ADDR + 0x008, 0x00333040)
MXC_DCD_ITEM(66, MMDC_P0_BASE_ADDR + 0x00c, 0x3F4352F3)
MXC_DCD_ITEM(67, MMDC_P0_BASE_ADDR + 0x010, 0xB66D8B63)
MXC_DCD_ITEM(68, MMDC_P0_BASE_ADDR + 0x014, 0x01FF00DB)

#MDMISC
MXC_DCD_ITEM(69, MMDC_P0_BASE_ADDR + 0x018, 0x00001740)
MXC_DCD_ITEM(70, MMDC_P0_BASE_ADDR + 0x01c, 0x00008000)
MXC_DCD_ITEM(71, MMDC_P0_BASE_ADDR + 0x02c, 0x000026D2)
MXC_DCD_ITEM(72, MMDC_P0_BASE_ADDR + 0x030, 0x00431023)
MXC_DCD_ITEM(73, MMDC_P0_BASE_ADDR + 0x040, 0x00000027)
MXC_DCD_ITEM(74, MMDC_P0_BASE_ADDR + 0x000, 0x831A0000)

# Initialize 2GB DDR3 - Micron MT41J128M
MXC_DCD_ITEM(75, MMDC_P0_BASE_ADDR + 0x01c, 0x02008032)
MXC_DCD_ITEM(76, MMDC_P0_BASE_ADDR + 0x01c, 0x00008033)
MXC_DCD_ITEM(77, MMDC_P0_BASE_ADDR + 0x01c, 0x00048031)
MXC_DCD_ITEM(78, MMDC_P0_BASE_ADDR + 0x01c, 0x05208030)
MXC_DCD_ITEM(79, MMDC_P0_BASE_ADDR + 0x01c, 0x04008040)

MXC_DCD_ITEM(80, MMDC_P0_BASE_ADDR + 0x020, 0x00007800)

MXC_DCD_ITEM(81, MMDC_P0_BASE_ADDR + 0x818, 0x00022227)
MXC_DCD_ITEM(82, MMDC_P1_BASE_ADDR + 0x818, 0x00022227)

MXC_DCD_ITEM(83, MMDC_P0_BASE_ADDR + 0x004, 0x0002556D)
MXC_DCD_ITEM(84, MMDC_P0_BASE_ADDR + 0x404, 0x00011006)
MXC_DCD_ITEM(85, MMDC_P0_BASE_ADDR + 0x01c, 0x00000000)

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Tue, 23 Jul 2013 22:51:06 GMT

Since I've had no luck with these solutions, let me ask a different question. How low can I set the DDR speed with the 528 MHz sourced periph_clk? Can I drop the DDR clk to 500? or 475? or 452? somehow without changing the input to periph_clk? If so, how would I go about this?

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Tue, 23 Jul 2013 22:52:20 GMT

How did you use the clk command? I was under the impression that this was not implemented for mx6q u-boot?

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

PKZ — Wed, 24 Jul 2013 02:38:43 GMT

Hi FM,

I created the thread Tuning DDR3 configurations on iMX6Q board. The issue is not solved yet.Re: Tuning DDR3 configurations on iMX6Q board

I am thinking to reduce the DDR speed to 500MHz or lower as the stress test looks ok at lower speed (500MHz). Any luck on slowing the DDR speed in Android?

Thanks.

Re: Slowing DDR3 clock for i.MX6Q

byungchul — Wed, 24 Jul 2013 08:21:27 GMT

Hi, FM

clk command usage.

*. step 1 --> 2 is ok, but direct to go down step2 failed.

MX6Q U-Boot > help clk
clk - Clock sub system

Usage:
clk Setup/Display clock
clk - Display all clocks
clk core <core clock in MHz> - Setup/Display core clock
clk periph <peripheral clock in MHz> -Setup/Display peripheral clock
clk ddr <DDR clock in MHz> - Setup/Display DDR clock
clk nfc <NFC clk in MHz> - Setup/Display NFC clock
Example:
clk - Show various clocks
clk core 665 - Set core clock to 665MHz
clk periph 600 - Set peripheral clock to 600MHz
clk ddr 166 - Set DDR clock to 166MHz

1. Down 480Mhz.

MX6Q U-Boot > clk periph 480
source=pll3

CBCMR=00020324
CBCDR=02018d00

MX6Q U-Boot > clk
cpu clock: 984MHz
mx6q pll1: 984MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock     : 60000000Hz
ipg per clock : 60000000Hz
uart clock    : 80000000Hz
cspi clock    : 60000000Hz
ahb clock     : 120000000Hz
axi clock   : 240000000Hz
emi_slow clock: 120000000Hz
ddr clock     : 480000000Hz
usdhc1 clock : 198000000Hz
usdhc2 clock : 198000000Hz
usdhc3 clock : 198000000Hz
usdhc4 clock : 198000000Hz
nfc clock     : 11000000Hz

2. Down 400Mhz.

MX6Q U-Boot > clk periph 400
source=pll2_pfd_400m

CBCMR=00060324
CBCDR=00018d00
MX6Q U-Boot > clk
cpu clock: 984MHz
mx6q pll1: 984MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock     : 49500000Hz
ipg per clock : 49500000Hz
uart clock    : 80000000Hz
cspi clock    : 60000000Hz
ahb clock     : 99000000Hz
axi clock   : 198000000Hz
emi_slow clock: 99000000Hz
ddr clock     : 396000000Hz
usdhc1 clock : 198000000Hz
usdhc2 clock : 198000000Hz
usdhc3 clock : 198000000Hz
usdhc4 clock : 198000000Hz
nfc clock     : 11000000Hz

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Wed, 24 Jul 2013 14:45:29 GMT

Thanks for this. I was using 'clk ddr ...' and that did not change the ddr clk. Interesting that 'clk periph ...' changes the ddr clk when there is a specific subcommand to set the ddr clk.

When I do 'clk periph 480' it seems to take. When I do 'clk periph 400' the board hangs. I do not get the source, CBCMR and CBCDR output. Did you modify your code to do that?

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

byungchul — Thu, 25 Jul 2013 04:06:32 GMT

Yes, i modified source code, as bellows.

u-boot : u-boot-2009.08

file : cpu/arm_cortexa8/mx6/generic.c

static int config_periph_clk(u32 ref, u32 freq)
{
u32 cbcdr = readl(CCM_BASE_ADDR + CLKCTL_CBCDR);
u32 cbcmr = readl(CCM_BASE_ADDR + CLKCTL_CBCMR);
u32 pll2_freq = __decode_pll(BUS_PLL2, CONFIG_MX6_HCLK_FREQ);
u32 pll3_freq = __decode_pll(USBOTG_PLL3, CONFIG_MX6_HCLK_FREQ);

if (freq >= pll2_freq) {
printf("source=pll2\n");
/* PLL2 */
writel(cbcmr & ~MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_MASK,
   CCM_BASE_ADDR + CLKCTL_CBCMR);
writel(cbcdr & ~MXC_CCM_CBCDR_PERIPH_CLK_SEL,
   CCM_BASE_ADDR + CLKCTL_CBCDR);
} else if (freq < pll2_freq && freq >= pll3_freq) {
printf("source=pll3\n");
/* PLL3 */
writel(cbcmr & ~MXC_CCM_CBCMR_PERIPH_CLK2_SEL_MASK,
   CCM_BASE_ADDR + CLKCTL_CBCMR);
writel(cbcdr | MXC_CCM_CBCDR_PERIPH_CLK_SEL,
   CCM_BASE_ADDR + CLKCTL_CBCDR);
} else if (freq < pll3_freq && freq >= PLL2_PFD2_FREQ) {
printf("source=pll2_pfd_400m\n");
/* 400M PLL2 PFD */
cbcmr = (cbcmr & ~MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_MASK) |
   (1 << MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_OFFSET);
writel(cbcmr, CCM_BASE_ADDR + CLKCTL_CBCMR);
writel(cbcdr & ~MXC_CCM_CBCDR_PERIPH_CLK_SEL,
   CCM_BASE_ADDR + CLKCTL_CBCDR);
} else if (freq < PLL2_PFD2_FREQ && freq >= PLL2_PFD0_FREQ) {
printf("source=pll2_pfd_325m\n");
/* 352M PLL2 PFD */
cbcmr = (cbcmr & ~MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_MASK) |
   (2 << MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_OFFSET);
writel(cbcmr, CCM_BASE_ADDR + CLKCTL_CBCMR);
writel(cbcdr & ~MXC_CCM_CBCDR_PERIPH_CLK_SEL,
   CCM_BASE_ADDR + CLKCTL_CBCDR);
} else if (freq == PLL2_PFD2_DIV_FREQ) {
printf("source=pll2_pfd_200m\n");
/* 200M PLL2 PFD */
cbcmr = (cbcmr & ~MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_MASK) |
   (3 << MXC_CCM_CBCMR_PRE_PERIPH_CLK_SEL_OFFSET);
writel(cbcmr, CCM_BASE_ADDR + CLKCTL_CBCMR);
writel(cbcdr & ~MXC_CCM_CBCDR_PERIPH_CLK_SEL,
   CCM_BASE_ADDR + CLKCTL_CBCDR);
} else {
printf("Frequency requested not within range [%d-%d] MHz\n",
   PLL2_PFD2_DIV_FREQ / SZ_DEC_1M, pll2_freq / SZ_DEC_1M);
return -1;
}
puts("\n");

// bcchae
printf("CBCMR=%08lx\n",readl(CCM_BASE_ADDR + CLKCTL_CBCMR));
printf("CBCDR=%08lx\n",readl(CCM_BASE_ADDR + CLKCTL_CBCDR));

return 0;
}

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Thu, 25 Jul 2013 04:20:53 GMT

Wow, what a great piece of code.

One question I have is this. If you change the clk settings don't you also have to also change the calibration parameters associated with the DDR3? If you set the clk to 400 MHz and don't change the calibrations, I would not expect things to work very well.

Thanks

Re: Slowing DDR3 clock for i.MX6Q

Chris1z — Thu, 25 Jul 2013 22:18:02 GMT

Hi byungchul,

I have a couple of questions for you:

1) What version of Android/Linux BSP are you running. I see that your initial clock values are different than mine. I'm using Android 4.2.2-1.1.0 ga on a SabreSD board. We have different cpu, ipg, ahb, axi and emi clocks.

MX6Q SABRESD U-Boot > clk

cpu clock: 792MHz

mx6q pll1: 792MHz

mx6q pll2: 528MHz

mx6q pll3: 480MHz

mx6q pll8: 50MHz

ipg clock : 66000000Hz

ipg per clock : 66000000Hz

uart clock : 80000000Hz

cspi clock : 60000000Hz

ahb clock : 132000000Hz

axi clock : 264000000Hz

emi_slow clock: 132000000Hz

ddr clock : 528000000Hz

usdhc1 clock : 198000000Hz

usdhc2 clock : 198000000Hz

usdhc3 clock : 198000000Hz

usdhc4 clock : 198000000Hz

nfc clock : 24000000Hz

2) If I use your procedure of changing the periph clock down to 480 first and then down to 400 I am able to see the clock change without hanging. But as soon as I type 'boot', it hangs when loading the kernel. Do you see this as well?

Re: Re: Slowing DDR3 clock for i.MX6Q

byungchul — Fri, 26 Jul 2013 00:07:32 GMT

Hi, FM

The answers are

MX6Q SABRESD U-Boot > clk

cpu clock: 792MHz

mx6q pll1: 792MHz

mx6q pll2: 528MHz

mx6q pll3: 480MHz

mx6q pll8: 50MHz

ipg clock : 66000000Hz

ipg per clock : 66000000Hz

uart clock : 80000000Hz

cspi clock : 60000000Hz

ahb clock : 132000000Hz

axi clock : 264000000Hz

emi_slow clock: 132000000Hz

ddr clock : 528000000Hz

usdhc1 clock : 198000000Hz

usdhc2 clock : 198000000Hz

usdhc3 clock : 198000000Hz

usdhc4 clock : 198000000Hz

nfc clock : 24000000Hz

OS : Linux 3.0.35, No android

Board : SabreSD

As cpu clock & pll1 is differrent, don't mind this values.

I was modified change the init cpu clock, for the fast booting.

OS booting failed at 400Mhz clock, but memory test is good in the u-boot.

Re: Slowing DDR3 clock for i.MX6Q

kladu — Thu, 09 Jan 2014 22:26:20 GMT

Hello Frank,

although an old topic, it is still marked "not answered". Were you able to slow down the DDR3 clock? We are experiencing similar problems.

I believe the answer to your last question is minimum 400MHz. It is defined in DDR3 chip. It depends on the CAS latency setup. Freescale uses 8 CLK CAS latency in their script, which is valid from 2.5ns to 1.875ns (400MHz to 533MHz) for an 1600MHz DDR3 device.

regards,

Borut

Re: Slowing DDR3 clock for i.MX6Q

frankmiller — Thu, 09 Jan 2014 22:55:10 GMT

Hi Borut,

I finally did get past this problem. Ultimately what I was trying to do was calibrate the DDR3 RAM against the 1.2 GHz Quad core part. I ended up having to go through this interesting procedure with the calibration tool.

First, I put the memory parameters into the DDR3 spreadsheet provided by Freescale.

I used the calibration values from this spreadsheet to seed the DDR3 calibration tool. I then ran the tool and got new calibration values. I took the output of this tool and fed the values back into the inputs of a second run of the tool. I did this several times until I discovered that output values were converging. I then took the converged output values and used them in the u-boot code for calibration and voila, the 4 GB of RAM has worked like a charm since. I hope this helps you.

Thanks,

Re: Slowing DDR3 clock for i.MX6Q

kladu — Fri, 10 Jan 2014 00:32:18 GMT

Thanks!

I never thought that calibration values would converge... We'll try it out.

Best regards,

Borut