Introduce a flag to indicate if the Qualcomm platform has a level
shifter for SD cards. With level shifter addition some extra delay is
seen on RX data path leading to CRC errors. To compensate these delays
and avoid CRC errors below things needs to be done:

1) Enable tuning for SDR50 mode
2) Limit HS mode frequency to 37.5MHz from 50MHz

Add this flag for all targets with a level shifter to handle these
issues for SD card.

Signed-off-by: Sarthak Garg <quic_sartgarg@quicinc.com>
---
 Documentation/devicetree/bindings/mmc/sdhci-msm.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml b/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
index b32253c60919..14f1ec9ae5bd 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
+++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
@@ -131,6 +131,9 @@ properties:
     $ref: /schemas/types.yaml#/definitions/uint32
     description: platform specific settings for DLL_CONFIG reg.
 
+  qcom,use-level-shifter:
+    description: Flag to indicate if platform has level shifter for SD card.
+
   iommus:
     minItems: 1
     maxItems: 8
-- 
2.17.1

On Thu, Nov 07, 2024 at 01:35:03PM +0530, Sarthak Garg wrote:
> Introduce a flag to indicate if the Qualcomm platform has a level
> shifter for SD cards. With level shifter addition some extra delay is
> seen on RX data path leading to CRC errors. To compensate these delays
> and avoid CRC errors below things needs to be done:
> 
> 1) Enable tuning for SDR50 mode
> 2) Limit HS mode frequency to 37.5MHz from 50MHz
> 
> Add this flag for all targets with a level shifter to handle these
> issues for SD card.
> 
> Signed-off-by: Sarthak Garg <quic_sartgarg@quicinc.com>
> ---
>  Documentation/devicetree/bindings/mmc/sdhci-msm.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 

This wasn't tested, so just short review - platform means SoC usually,
so this looks SoC specific, thus implied by compatible.

Best regards,
Krzysztof

On Thu, 07 Nov 2024 13:35:03 +0530, Sarthak Garg wrote:
> Introduce a flag to indicate if the Qualcomm platform has a level
> shifter for SD cards. With level shifter addition some extra delay is
> seen on RX data path leading to CRC errors. To compensate these delays
> and avoid CRC errors below things needs to be done:
> 
> 1) Enable tuning for SDR50 mode
> 2) Limit HS mode frequency to 37.5MHz from 50MHz
> 
> Add this flag for all targets with a level shifter to handle these
> issues for SD card.
> 
> Signed-off-by: Sarthak Garg <quic_sartgarg@quicinc.com>
> ---
>  Documentation/devicetree/bindings/mmc/sdhci-msm.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml: qcom,use-level-shifter: missing type definition

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20241107080505.29244-2-quic_sartgarg@quicinc.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.