Re: [PATCH] ARM: tegra: beaver: Allow SD card voltage to be changed

[Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org>]

On Thu, Jun 30, 2016 at 05:32:08PM +0200, Thierry Reding wrote:
> From: Lucas Stach <dev-8ppwABl0HbeELgA04lAiVw@public.gmane.org>
> 
> This allows to switch the card signal voltage level to 1.8 V, which is
> needed for any ultra high speed modes to work.
> 
> Signed-off-by: Lucas Stach <dev-8ppwABl0HbeELgA04lAiVw@public.gmane.org>
> Acked-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
> Hi ARM-SoC maintainers,
> 
> Can you please apply this for v4.7? It fixes a regression with UHS modes
> that I had hoped could be fixed in the MMC core, but it turns out that a
> fairly invasive change will be required and it's not going to make v4.7.
> 
> I should note that this is not a workaround. It is the proper fix to
> enable UHS modes, but it exposes a weakness in the SDHCI driver which
> will happily switch to UHS modes whether or not the power supply can be
> configured to output the required voltage. Ideally the SDHCI driver will
> be taught to reject UHS modes if the available supply voltages aren't
> suitable. There is work underway to do that, but it won't make v4.7.

Applied to fixes.


-Olof