Re: [PATCH 0/2] Fix reboot issue on Odroid boards with eMMC card

[Sjoerd Simons <sjoerd.simons@collabora.co.uk>]

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On Tue, 2015-01-27 at 09:11 +0100, Marek Szyprowski wrote:
> Hello,
> 
> This patchset fixes reboot hang issue on Hardkernel's Odroid boards with
> eMMC card. Those boards are designed in such a way, that the eMMC nreset
> signal is routed to SoC GPIO line instead of the board reset logic. To
> properly restard system, one need to set this line to zero before
> performing reboot.
> 
> The initial patches consisted of a complete reset/power off driver, but
> after further analysis, it turned out that only eMMC nreset line control
> logic is specific for those boards. Everything else can be done by
> generic Exynos code, so the code has been moved to Exynos DW MMC driver.

This seems a general board design quirk, rather then an exynos specific
one. Potentially better to have this in the mmc core so it can be
re-used by non-exynos boards?

A very quick peek at the schematic for the hardkernel C1 (amlogic
based), shows that for that board the eMMC reset line is hooked up to an
SoC gpio line as well. (Although ofcourse, it may not need to be reset
before a warm restart depending on what the amlogic rom code does).


Random side-note, at least the samsung peach chromebooks are also hooked
up this way. But don't run into this issue as they load their initial
stages from flash rather then the eMMC. 


> Best regards
> Marek Szyprowski
> Samsung R&D Institute Poland
> 
> 
> Changelog:
> 
> initial version:
> http://thread.gmane.org/gmane.linux.power-management.general/51855/
> 
> 
> Path summary:
> 
> Marek Szyprowski (2):
>   mmc: dw_mmc-exynos: add support for controlling emmc reset pin
>   ARM: dts: exynos*-odroid*: add eMMC reset line
> 
>  .../devicetree/bindings/mmc/exynos-dw-mshc.txt     |  6 +++
>  arch/arm/boot/dts/exynos4412-odroid-common.dtsi    |  1 +
>  arch/arm/boot/dts/exynos5422-odroidxu3.dts         |  1 +
>  drivers/mmc/host/dw_mmc-exynos.c                   | 43 +++++++++++++++++++++-
>  4 files changed, 50 insertions(+), 1 deletion(-)
> 



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