Some Microcenter/Patriot SD cards and Kingston eMMC are failing init
across Sitara K3 boards. Init failure is due to the sequence when
V1P8_SIGNAL_ENA is set. The V1P8_SIGNAL_ENA has a timing component tied
to it where if set, switch to full-cycle timing happens. The failing
cards do not like change to full-cycle timing before changing bus
width, so add flag to sdhci-am654 binding to suppress V1P8_SIGNAL_ENA
before changing bus width. The switch to full-cycle timing should happen
with HIGH_SPEED_ENA after change of bus width.

Signed-off-by: Judith Mendez <jm@ti.com>
---
 Documentation/devicetree/bindings/mmc/sdhci-am654.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
index 676a74695389..0f92bbf8e13b 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
+++ b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
@@ -201,6 +201,11 @@ properties:
       and the controller is required to be forced into Test mode
       to set the TESTCD bit.
 
+  ti,suppress-v1p8-ena:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      When present, V1P8_SIGNAL_ENA shall be suppressed.
+
 required:
   - compatible
   - reg
-- 
2.49.0

On Tue, Apr 22, 2025 at 05:05:10PM GMT, Judith Mendez wrote:
> Some Microcenter/Patriot SD cards and Kingston eMMC are failing init
> across Sitara K3 boards. Init failure is due to the sequence when
> V1P8_SIGNAL_ENA is set. The V1P8_SIGNAL_ENA has a timing component tied
> to it where if set, switch to full-cycle timing happens. The failing
> cards do not like change to full-cycle timing before changing bus
> width, so add flag to sdhci-am654 binding to suppress V1P8_SIGNAL_ENA
> before changing bus width. The switch to full-cycle timing should happen
> with HIGH_SPEED_ENA after change of bus width.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>
> ---
>  Documentation/devicetree/bindings/mmc/sdhci-am654.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> index 676a74695389..0f92bbf8e13b 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
> @@ -201,6 +201,11 @@ properties:
>        and the controller is required to be forced into Test mode
>        to set the TESTCD bit.
>  
> +  ti,suppress-v1p8-ena:

Do not tell what the drivers should do, but tell what is the issue with
the hardware, e.g. some cards do not like full-cycle.... and this will
also hint you that it should be most likely generic, not specific to
this device.

> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:

Best regards,
Krzysztof

Hi Krzysztof,

On 4/25/25 2:48 AM, Krzysztof Kozlowski wrote:
> On Tue, Apr 22, 2025 at 05:05:10PM GMT, Judith Mendez wrote:
>> Some Microcenter/Patriot SD cards and Kingston eMMC are failing init
>> across Sitara K3 boards. Init failure is due to the sequence when
>> V1P8_SIGNAL_ENA is set. The V1P8_SIGNAL_ENA has a timing component tied
>> to it where if set, switch to full-cycle timing happens. The failing
>> cards do not like change to full-cycle timing before changing bus
>> width, so add flag to sdhci-am654 binding to suppress V1P8_SIGNAL_ENA
>> before changing bus width. The switch to full-cycle timing should happen
>> with HIGH_SPEED_ENA after change of bus width.
>>
>> Signed-off-by: Judith Mendez <jm@ti.com>
>> ---
>>   Documentation/devicetree/bindings/mmc/sdhci-am654.yaml | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
>> index 676a74695389..0f92bbf8e13b 100644
>> --- a/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
>> +++ b/Documentation/devicetree/bindings/mmc/sdhci-am654.yaml
>> @@ -201,6 +201,11 @@ properties:
>>         and the controller is required to be forced into Test mode
>>         to set the TESTCD bit.
>>   
>> +  ti,suppress-v1p8-ena:
> 
> Do not tell what the drivers should do, but tell what is the issue with
> the hardware, e.g. some cards do not like full-cycle.... and this will
> also hint you that it should be most likely generic, not specific to
> this device.
> 

Thanks for your review, but this patch has been dropped in v4 since
we adopted a new implementation [0] using compatible string.

[0] 
https://lore.kernel.org/linux-devicetree/20250423180809.l3l6sfbwquaaazar@shrank/

~ Judith