We need to work with 400MHz DDR configuration with a iMX6Q Dual processor. We success to configure pll2 to 396MHz in u-boot thanks to existing forum exchanges (how to change DDR clock of i.mx6)
But linux 3.10.17 kernel hangs when starting :
U-Boot 2014.04-OTG-PR3149_V0.9.9 (Nov 21 2014 - 11:19:24)
CPU: Freescale i.MX6D rev1.5 at 792 MHz
Reset cause: POR
Board: HCBT_PLUS
I2C: ready
DRAM: 1 GiB
MMC: FSL_SDHC: 0
SF: Detected M25P64 with page size 256 Bytes, erase size 64 KiB, total 8 MiB
No panel detected: default to vga-lvds
Display: vga-lvds (640x480)
In: serial
Out: serial
Err: serial
board_late_init(): MFG_BOOT
Net: using phy at 0
FEC [PRIME], usb_ether
Hit any key to stop autoboot: 0
U-Boot-EVP > clocks
PLL_SYS 792 MHz
PLL_BUS 528 MHz
PLL_OTG 480 MHz
PLL_NET 50 MHz
IPG 49500 kHz
UART 80000 kHz
CSPI 60000 kHz
AHB 99000 kHz
AXI 198000 kHz
DDR 396000 kHz
USDHC1 198000 kHz
USDHC2 198000 kHz
USDHC3 198000 kHz
USDHC4 198000 kHz
EMI SLOW 99000 kHz
IPG PERCLK 49500 kHz
U-Boot-EVP > boot
## Booting kernel from Legacy Image at 12000000 ...
Image Name: Linux-3.10.17-OTG-PR3149_V1.0.0
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 4911160 Bytes = 4.7 MiB
Load Address: 10008000
Entry Point: 10008000
Verifying Checksum ... OK
## Loading init Ramdisk from Legacy Image at 12c00000 ...
Image Name: initramfs
Image Type: ARM Linux RAMDisk Image (gzip compressed)
Data Size: 17238142 Bytes = 16.4 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
## Flattened Device Tree blob at 18000000
Booting using the fdt blob at 0x18000000
Loading Kernel Image ... OK
Loading Ramdisk to 4e4e2000, end 4f55287e ... OK
Loading Device Tree to 4e4d4000, end 4e4e16fc ... OK
Starting kernel ...
We try to make some changes in busfreq_ddr3.c and ddr3_freq_imx6.S files but we don't find a way to have functionnal kernel with 400Mhz DDR clock.
We also add in our devicetree definition such as :
| soc { |
| | busfreq { /* BUSFREQ */ |
| | | compatible = "fsl,imx6_busfreq"; |
| | | clocks = <&clks 171>, <&clks 6>, <&clks 11>, <&clks 104>, <&clks 172>, <&clks 58>, |
| | | <&clks 18>, <&clks 60>, <&clks 20>, <&clks 3>; |
| | | clock-names = "pll2_bus", "pll2_pfd2_396m", "pll2_198m", "arm", "pll3_usb_otg", "periph", |
| | | "periph_pre", "periph_clk2", "periph_clk2_sel", "osc"; |
| | | interrupts = <0 107 0x04>, <0 112 0x4>, <0 113 0x4>, <0 114 0x4>; |
| | | interrupt-names = "irq_busfreq_0", "irq_busfreq_1", "irq_busfreq_2", "irq_busfreq_3"; |
| | | fsl,max_ddr_freq = <40000000>; |
| | }; |
| }; |
Our specific DDR initialization is present for information.
Our request is as follow:
What it the correct way to configure or to stay with 400MHz DDR clock with 3.10.17 (or above) linux kernel ?
Thanks by advance for help you can bring us.
Gabriel GRANGE
Original Attachment has been moved to: iMX6_1066mhz_4x128mx16-centralp_V1.cfg.zip
