which files need to be changed in kernel for shift ddr3 to LPDDR2

[srinivasaporam]

Hi,

We have got IMX6D custom designed board which is based on IMX6Q reference design (Wandboard). Following are the main differences between reference and custom boards:

1. Memory shift from DDR3 (2GB) to LPDDR2 (512MB)

2. Reference board is IMX6Q /DL where as custom board is IMx6D (Dual)

We have modified U-boot, such atht both reference board and custom board are passing the U-boot level. Coming to the Kernel (3.10.53) reference board is able load kernel completely and booted.  where as custom board, it is locking up at "Starting Kernel..."

Did i miss some changes to be made in  kernel.

[srinivasaporam]

Hi,

I have put some printk statements in kernel and found out that  my ccm (fsl,imx6q-ccm) is not getting initialized properly.

and further debugging, kernel is stucking at this point  (clk-imx6q.c)

writel_relaxed(1 << CCM_CCGR_OFFSET(0), base + 0x7c);

writel_relaxed(0, base + 0x80);

what could be possible error????

[Yuri]

Hello,

You may create new request regarding details how to configure memory frequency

of 400MHz.

1)	Please open www.nxp.com
2)	On the top level menu, select Support > Sales and Support (http://www.nxp.com/support/sales-and-support:SUPPORTHOME).
3)	On the bottom of the page, select Hardware & Software.
4)	Register with your business email to access the technical NXP online support.
5)	A verification email will be sent to your account. Click the embedded link to verify your access.
6)	On the NXP online support page, select Contact Support from the top menu and click “submit a new case” to start the process.

Regards,

Yuri.

[srinivasaporam]

Hi,

One more thing i forgot to mention is my LPDDR2 (512MB) is 400MHZ where as Reference board is DDR3(2GB) is 528 MHz. When checked in arch/arm/mach-imx there is file named "ddr3_freq_imx6.S" where in one place it is mentioned that

ldr    r1, =528000000

DDR3 or LPDDR2 clock frequency will be passed by U-boot or it will be taken from kernel files. Can i edit this ldr r1=400000000 such that it will be changed to my LPDDR2 setting.

[Yuri]

Hi,

  As for frequency 400 MHz setting, please refer to i.MX6DL LPDDR2 Support for L3.0.35_4.0.0

Regards,

Yuri.

[srinivasaporam]

Hi,

board is IMX6D but not IMX6DL. How this patch will work???

[srinivasaporam]

Hi,

Iam narrow downing my problem to dts files. I want check the dts files generated were exactly same as that of our custom board. But, There are some loop hole like:

dts for reference board has ldb

&ldb {

    clocks = <&clks IMX6QDL_CLK_LDB_DI0_SEL>, <&clks IMX6QDL_CLK_LDB_DI1_SEL>,

         <&clks IMX6QDL_CLK_IPU1_DI0_SEL>, <&clks IMX6QDL_CLK_IPU1_DI1_SEL>,

         <&clks IMX6QDL_CLK_IPU2_DI0_SEL>, <&clks IMX6QDL_CLK_IPU2_DI1_SEL>,

         <&clks IMX6QDL_CLK_LDB_DI0>, <&clks IMX6QDL_CLK_LDB_DI1>;

    clock-names = "di0_pll", "di1_pll",

              "di0_sel", "di1_sel", "di2_sel", "di3_sel",

              "di0", "di1";

    lvds-channel@0 {

        port@2 {

            reg = <2>;

            lvds0_mux_2: endpoint {

                remote-endpoint = <&ipu2_di0_lvds0>;

            };

        };

        port@3 {

            reg = <3>;

            lvds0_mux_3: endpoint {

                remote-endpoint = <&ipu2_di1_lvds0>;

            };

        };

    };

    lvds-channel@1 {

        port@2 {

            reg = <2>;

            lvds1_mux_2: endpoint {

                remote-endpoint = <&ipu2_di0_lvds1>;

            };

        };

        port@3 {

            reg = <3>;

            lvds1_mux_3: endpoint {

                remote-endpoint = <&ipu2_di1_lvds1>;

            };

        };

    };

};

But we are not using any ldb or lvds modules. Our board has only HDMI. Will there be any harm if this ldb is define as above in our custom board.

Also we don't know some of the devices/modules like  dcic1,dcic2, caam-sm@00100000,gpt,anatop,tempmon,snvs,epit1,epit2, src,gpc,gpr,romcp,weim, octop,tzosc,vdoa, mlb etc... whether they are required.... what if we keep them dts files.

How to generate exact device tree source files for our custom boards.

we have used pmic for power generation, then how to include that in device tree. what are minimum modules which are reuired for kernel to boot. How will we come to know, which are really important and which are not????

[Yuri]

Please refer to "i.MX_BSP_Porting_Guide.pdf" in BSP documentation.

~Yuri.

[srinivasaporam]

Hi,

We tried it and it has passed the stress test. Now Why reference board is able to boot the kernel 3.10.53 and why not the custom board.

The custom board u-boot has been modified for LPDDR2 (400 MHz) 512 MB

static void ccgr_init(void)

{

    struct mxc_ccm_reg *ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;

    writel(0xFFFFFFFF, &ccm->CCGR0);

    writel(0xFFFFFFFF, &ccm->CCGR1);

    writel(0xFFFFFFFF, &ccm->CCGR2);

    writel(0xFFFFFFFF, &ccm->CCGR3);

    writel(0xFFFFFFFF, &ccm->CCGR4);

    writel(0xFFFFFFFF, &ccm->CCGR5);

    writel(0xFFFFFFFF, &ccm->CCGR6);

     writel(0x00060324, &ccm->cbcmr); // this denotes that DDR clock is 400 MHz.

}

Uboot is modified for LPDDR2 and it is coming till starting kernel.

Now,

for reference board and custom board kernelo is the same (as per freescale kernel files need not be changed).

can any body tell, what is making reference board to boot and custom board is hanging/stucking.

Please suggest us...

[Yuri]

Hi,

The following may be helpful :

i.MX6DL LPDDR2 Support for L3.0.35_4.0.0

Regards,
Yuri.

[srinivasaporam]

Environment variables (printenv) lists out : baudrate=115200
board_name=C1
board_rev=MX6Q
boot_fdt=try
bootargs_base=setenv bootargs console =ttymxc0,115200

bootcmd=run findfdt; setenv mmcdev 0;setenv mmckernel 0;run mmcboot;setenv mmcd;

bootdelay=3
bootscript=echo Running bootscript from mmc ...; source
console=ttymxc0,115200
ethact=FEC
ethprime=FEC
fdt_addr=0x18000000
fdt_high=0xffffffff
fdtfile=undefined

findfdt=if test $board_name = C1 && test $board_rev = MX6Q ; then setenv fdtfil

image=zImage
initrd_high=0xffffffff
ip_dyn=yes
loadaddr=0x12000000
loadbootscript=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${script};

loadfdt=echo loading ${fdtdir}/${fdtfile} ...;  load mmc ${bootpart} ${fdt_addr}

loadimage=load mmc ${bootpart} ${loadaddr} ${bootdir}/${bootfile}

loadrd=load mmc ${bootpart} ${rdaddr} ${bootdir}/${rdfile}; setenv rdsize ${fil}

mmcargs=setenv bootargs root=/dev/mmcblk2p1 rw rootwait earlyprintk

mmcboot=mmc dev ${mmcdev}; if mmc rescan; then echo SD/MMC found on device ${mm;

mmcboot_old=echo Booting from mmc ...; mmcboot=echo Booting from mmc ...; run m;

mmcdev=0
mmcpart=1
mmcroot=/dev/mmcblk0p2 ro
mmcrootfstype=ext4 rootwait

netargs=setenv bootargs console=${console},${baudrate} root=/dev/nfs ip=dhcp nfp

netboot=echo Booting from net ...; run netargs; if test ${ip_dyn} = yes; then s;

rdaddr=0x12A00000
script=boot.scr
splashpos=m,m

uname_boot=setenv bootdir /boot; setenv bootfile vmlinuz-${uname_r}; if test -e;

update_sd_firmware=if test ${ip_dyn} = yes; then setenv get_cmd dhcp; else setei

update_sd_firmware_filename=u-boot.imx

videoargs=setenv nextcon 0; if hdmidet; then setenv bootargs ${bootargs} video=}

Environment size: 5961/8188 bytes

[Yuri]

Have You tried to test memory ?

i.MX6/7 DDR Stress Test Tool V2.40

~Yuri.

[srinivasaporam]

Hi,

I have downloaded the kernel source from "wandboard-org/linux · GitHub " . may be it is having issues with custom board.

If i would like to  try linux from IMX6 from where should i try ??? I don't want to go for Yocto. I would like to try ubuntu

Please guide me...

[Yuri]

Hi,

FSL \ NXP Linux BSPs may be found at
i.MX6Q|i.MX 6Quad Processors|Quad Core|NXP

section "Board Support Packages"

Also the following may be useful :

Ubuntu image for MX6UL

Regards,

Yuri.

[srinivasaporam]

Hi,

=> md.l 80d60780 28  resulting in
80d60780: 083449c2 18b50101 ffa54079 8b534daa	.I4.....y@...MS.
80d60790: 75e4d101 277a1534 abc14318 36ec7563	...u4.z'.C..cu.6
80d607a0: cc060a4a 402002c0 72805382 47f4822b	J..... @.S.r+..G
80d607b0: e4e5e22c 231955cb 09414486 204c2200	,....U.#.DA.."L
80d607c0: 16478014 486ab054 250dd902 01418044	..G.T.jH...%D.A.
80d607d0: 84a9c151 02a79a44 59fe3a5b ac57c0d3	Q...D...[:.Y..W.
80d607e0: b54f7060 4806c429 12800a88 d060005a	`pO.)..H....Z.`.
80d607f0: a3c2c941 ca890144 81827145 d5745707	A...D...Eq...Wt.
80d60800: 1aea30cd 8360405e d08e1810 100dc164	.0..^@`.....d...
80d60810: 28f74344 ca785204 e2ae510a 0047510f	DC.(.Rx..Q...QG.

[srinivasaporam]

Hi,

$readelf -s vmlinux | grep __log_buf is resulting in

39342: 80d60780 0x40000 OBJECT  LOCAL  DEFAULT   28 __log_buf

this i have checked from vmlinux in the folder (/linux/) in my host, which has been generated by cross compilation.

Now can i use this in u-boot of target board

[srinivasaporam]

Hi,

where should i run readelf utility...

this board hasn't booted once also. it is stopping at "starting Kernel ..." from beginning after the board is assembled with this kernel.

[Yuri]

Readelf - on the host ; vmlinux - kernel ELF file.

~Yuri.

[Yuri]

Hello,

  Basically it is enough to modify U-boot, as described in Chapter 1 (Porting U-Boot
from an i.MX 6/7 Reference Board to an i.MX 6/7 Custom Board) of “i.MX_BSP_Porting_Guide.pdf”
in FSL / NXP  Linux documentation.

  If a board boots u-boot but stops at “Starting kernel ...”, it may be possible to read the kernel
log_buffer. to view memory dump (say in ASCII) at the needed address, assuming memory still contains
log information from the previous boot.  

To find the __log_buf address, please use readelf utility :

$ readelf -s vmlinux | grep __log_buf

Then, don’t power off the board, just reset it, and read the

(__log_buf) address on JTAG or u-boot. As an example :

U-Boot > md.l 10af37b8 50

Have a great day,
Yuri

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