From: Tony Lindgren <tony@atomide.com>
To: Faiz Abbas <faiz_abbas@ti.com>
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
Subject: Re: [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card
Date: Thu, 2 May 2019 07:20:16 -0700 [thread overview]
Message-ID: <20190502142016.GO8007@atomide.com> (raw)
In-Reply-To: <20190502084748.22518-1-faiz_abbas@ti.com>
* Faiz Abbas <faiz_abbas@ti.com> [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 <faiz_abbas@ti.com>
> ---
> 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
>
next prev parent reply other threads:[~2019-05-02 14:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-02 8:47 [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card Faiz Abbas
2019-05-02 14:20 ` Tony Lindgren [this message]
2019-05-02 14:30 ` Faiz Abbas
2019-05-02 14:35 ` Tony Lindgren
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