From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card Date: Thu, 2 May 2019 07:20:16 -0700 Message-ID: <20190502142016.GO8007@atomide.com> References: <20190502084748.22518-1-faiz_abbas@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190502084748.22518-1-faiz_abbas@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Faiz Abbas Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-omap@vger.kernel.org, mark.rutland@arm.com, robh+dt@kernel.org, bcousson@baylibre.com, ulf.hansson@linaro.org, adrian.hunter@intel.com List-Id: devicetree@vger.kernel.org * Faiz Abbas [190502 01:48]: > If UHS speed modes are enabled, a compatible SD card switches down to > 1.8V during enumeration. If after this a software reboot/crash takes > place and on-chip ROM tries to enumerate the SD card, the difference in > IO voltages (host @ 3.3V and card @ 1.8V) may end up damaging the card. > > The fix for this is to have support for power cycling the card in > hardware (with a PORz/soft-reset line causing a power cycle of the > card). Since am571x-, am572x- and am574x-idk don't have this > capability, disable voltage switching for these boards. > > The major effect of this is that the maximum supported speed > mode is now high speed(50 MHz) down from SDR104(200 MHz). This sounds a bit urgent, does it also need a stable tag or is it safe to apply against any earlier kernels? Regards, Tony > Signed-off-by: Faiz Abbas > --- > arch/arm/boot/dts/am57xx-idk-common.dtsi | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/boot/dts/am57xx-idk-common.dtsi b/arch/arm/boot/dts/am57xx-idk-common.dtsi > index f7bd26458915..42e433da79ec 100644 > --- a/arch/arm/boot/dts/am57xx-idk-common.dtsi > +++ b/arch/arm/boot/dts/am57xx-idk-common.dtsi > @@ -420,6 +420,7 @@ > vqmmc-supply = <&ldo1_reg>; > bus-width = <4>; > cd-gpios = <&gpio6 27 GPIO_ACTIVE_LOW>; /* gpio 219 */ > + no-1-8-v; > }; > > &mmc2 { > -- > 2.19.2 >