From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olof Johansson Subject: Re: [PATCH] ARM: tegra: beaver: Allow SD card voltage to be changed Date: Wed, 6 Jul 2016 22:22:06 -0700 Message-ID: <20160707052206.GI32389@localhost> References: <20160630153208.22761-1-thierry.reding@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160630153208.22761-1-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: arm-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, Lucas Stach , Jon Hunter , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On Thu, Jun 30, 2016 at 05:32:08PM +0200, Thierry Reding wrote: > From: Lucas Stach > > 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 > Acked-by: Jon Hunter > Signed-off-by: Thierry Reding > --- > 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