[PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card

[PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card

[Faiz Abbas]

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).

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

Re: [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card

[Tony Lindgren]

* 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
> 

Re: [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card

[Faiz Abbas]

Hi Tony,

On 02/05/19 7:50 PM, Tony Lindgren wrote:
> * 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?
> 

This should be good to apply on any previous releases.

Thanks,
Faiz

Re: [PATCH] ARM: dts: am57xx-idk: Remove support for voltage switching for SD card

[Tony Lindgren]

* Faiz Abbas <a0230074@ti.com> [190502 14:30]:
> Hi Tony,
> 
> On 02/05/19 7:50 PM, Tony Lindgren wrote:
> > * 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?
> > 
> 
> This should be good to apply on any previous releases.

OK applying both your MMC patches into fixes today.

Thanks,

Tony