Jian-Hong Pan jhp@endlessos.org 於 2021年7月7日 週三 下午12:23寫道：
Hi,
I tried to boot Linux next kernel at tag 5.13.0-next-20210701 from latest U-Boot at commit 1311dd37ec ("Merge branch '2021-07-01-update-CI-containers'") on Raspberry Pi 400.
- U-Boot goes with the bcm2711-rpi-400.dtb from Raspberry Pi OS
firmware at tag 1.20210527 [1]. U-Boot is built with the rpi_4_defconfig.
- The Linux next kernel goes with the corresponding
bcm2711-rpi-400.dtb at tag 5.13.0-next-20210701. However, the Linux kernel is stuck at failed mmc, which keeps showing "mmc1: invalid bus width":
[ 7.776752] mmc1: invalid bus width [ 7.781398] mmc1: error -22 whilst initialising SD card [ 17.891183] mmc1: Timeout waiting for hardware cmd interrupt. [ 17.900265] mmc1: sdhci: ============ SDHCI REGISTER DUMP =========== [ 17.910046] mmc1: sdhci: Sys addr: 0x00000000 | Version: 0x00001002 [ 17.919829] mmc1: sdhci: Blk size: 0x00000000 | Blk cnt: 0x00000000 [ 17.929595] mmc1: sdhci: Argument: 0x80000c08 | Trn mode: 0x00000000 [ 17.939337] mmc1: sdhci: Present: 0x1fff0001 | Host ctl: 0x00000001 [ 17.949092] mmc1: sdhci: Power: 0x0000000f | Blk gap: 0x00000080 [ 17.958827] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x0000f447 [ 17.968531] mmc1: sdhci: Timeout: 0x00000000 | Int stat: 0x00000000 [ 17.978201] mmc1: sdhci: Int enab: 0x00ff1003 | Sig enab: 0x00ff1003 [ 17.987850] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000 [ 17.997456] mmc1: sdhci: Caps: 0x45ee6432 | Caps_1: 0x0000a525 [ 18.007044] mmc1: sdhci: Cmd: 0x0000341a | Max curr: 0x00080008 [ 18.016622] mmc1: sdhci: Resp[0]: 0x00000000 | Resp[1]: 0x00000000 [ 18.026157] mmc1: sdhci: Resp[2]: 0x00000000 | Resp[3]: 0x00000000 [ 18.035650] mmc1: sdhci: Host ctl2: 0x00000000 [ 18.043066] mmc1: sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x00000000 [ 18.052540] mmc1: sdhci: ============================================ [ 18.139162] mmc1: invalid bus width [ 18.144682] mmc1: error -22 whilst initialising SD card [ 19.498785] mmc1: invalid bus width [ 19.503344] mmc1: error -22 whilst initialising SD card
The full log can be foud at https://gist.github.com/starnight/dec6e6ee627f19c2d291f3ff973b06fa#file-uboo...
In Linux kernel, SD card driver checks the bus_width bits for validation [2] in mmc_decode_scr(). The value of bus_width comes from the resp, which is assigned from mmc_card's raw_scr. However, the values of resp[0..3] are 0, which means no SD_SCR_BUS_WIDTH_1, nor SD_SCR_BUS_WIDTH_4. After studied the call trace of mmc_decode_scr(), learned that mmc_sd_init_card() -> mmc_app_send_scr() gets and assigns mmc_card's raw_scr value [3] with "DMA" mechanism.
Therefore, I try to boot the same Linux next kernel with the same corresponding bcm2711-rpi-400.dtb at tag 5.13.0-next-20210701 directly, without u-boot. The system boots up and the mmc works correctly. The full log can be found at https://gist.github.com/starnight/dec6e6ee627f19c2d291f3ff973b06fa#file-kern...
Is there something special that should be done in U-Boot for Raspberry Pi 400?
[1] https://github.com/raspberrypi/firmware/blob/1.20210527/boot/bcm2711-rpi-400... [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/dri... [3] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/dri...
I notice that mainline kernel 5.14-rc* includes the Raspberry Pi 400 device tree commits. So, I build latest kernel 5.14-rc2. The kernel still boot failed at "mmc1: invalid bus width" on RPi 400.
To make it easy to track, I filed this bug on kernel's bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213753
BR. Jian-Hong Pan