On Wed, Feb 18, 2015 at 11:50:41AM +0100, Przemyslaw Marczak wrote:
Hello Simon,
On 02/18/2015 06:02 AM, Simon Glass wrote:
Hi Przemyslaw,
On 17 February 2015 at 06:09, Przemyslaw Marczak p.marczak@samsung.com wrote:
Before this commit, the mmc devices were always registered in the same order. So dwmmc channel 0 was registered as mmc 0, channel 1 as mmc 1, etc. In case of possibility to boot from more then one device, the CONFIG_SYS_MMC_ENV_DEV should always point to right mmc device.
This can be achieved by init boot device as first, so it will be always registered as mmc 0. Thanks to this, the 'saveenv' command will work fine for all mmc boot devices.
Exynos based boards usually uses mmc host channels configuration:
- 0, or 0+1 for 8 bit - as a default boot device (usually eMMC)
- 2 for 4bit - as an optional boot device (usually SD card slot)
And usually the boot order is defined by OM pin configuration, which can be changed in a few ways, eg.
- Odroid U3 - eMMC card insertion -> first boot from eMMC
- Odroid X2/XU3 - boot priority jumper
By this commit, Exynos dwmmc driver will check the OM pin configuration, and then try to init the boot device and register it as mmc 0.
I think a better way to do this would be to make CONFIG_SYS_MMC_ENV_DEV support an option where the device can be selected at run-time.
However that would probably be better done when the drive rmodel conversion is complete.
So this seems a reasonable patch given where we are.
Reviewed-by: Simon Glass sjg@chromium.org
This was just a quick solution to solve the issue on XU3, when the same binary can boot from sd or eMMC slots.
XU3 isn't unique in this regard. "am335x_evm" binaries runs on 4 very different boards and we still just have to say that sometimes we default to ENV in a place that isn't workable.