At the moment the fastboot code relies on the Kconfig variable CONFIG_FASTBOOT_FLASH_MMC_DEV to point to the MMC device to use for the flash command. This value needs to be the *U-Boot device number*, which is picked by the U-Boot device model at runtime. This makes it quite tricky and fragile to fix this variable at compile time, as other DT nodes and aliases influence the enumeration process.
To make this process more robust, allow the device number to be picked at runtime, which sounds like a better fit to find this device number. Patch 1/3 introduces a weak function for that purpose. Patch 2/3 then implements this function for the Allwinner platform. The code follows the idea behind the existing Kconfig defaults: Use the eMMC device, if that exists, or the SD card otherwise. This patch is actually not sunxi specific, so might be adopted by other platforms as well. Patch 3/3 then drops the existing Kconfig defaults for sunxi, to clean this up and remove the implicit assumption that the eMMC device is always device 1 (as least for the fastboot code). I would be curious if others think this is the right way forward. The fact that the U-Boot device numbers are determined at runtime seems to conflict with the idea of a Kconfig variable in the first place, hence this series. This brings us one step closer to the end goal of removing the "eMMC is device 1" assumption. I am looking forward to any comments on this series! Cheers, Andre Andre Przywara (3): fastboot: Allow runtime determination of MMC device sunxi: Implement fastboot_get_mmc_device() sunxi: Drop sunxi FASTBOOT_FLASH_MMC_DEV defaults board/sunxi/board.c | 37 +++++++++++++++++++++++++++++++++++ drivers/fastboot/Kconfig | 4 +--- drivers/fastboot/fb_command.c | 6 +++--- drivers/fastboot/fb_common.c | 3 ++- drivers/fastboot/fb_mmc.c | 12 ++++++++---- include/fastboot.h | 7 +++++++ 6 files changed, 58 insertions(+), 11 deletions(-) -- 2.17.5
