[PATCH v2 0/3] dt-bindings: mmc: / ARM: qcom: add MSM8998 and cleanup driver of_device_id

[PATCH v2 0/3] dt-bindings: mmc: / ARM: qcom: add MSM8998 and cleanup driver of_device_id

[Krzysztof Kozlowski]

Hi,

Changes since v1:
1. Add Rb tags.
2. Rework driver patch (now last in the series), after talk with Doug.

https://lore.kernel.org/linux-devicetree/CAD=FV=WGxQF4vPuRi7kWKoqTpe0RFsgH+J82C=sQbmncK_AFpw@mail.gmail.com/

Best regards,
Krzysztof

Cc: Konrad Dybcio <konrad.dybcio@somainline.org>
Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>

Krzysztof Kozlowski (3):
  dt-bindings: mmc: sdhci-msm: add MSM8998
  arm64: dts: qcom: msm8998: add MSM8998 SDCC specific compatible
  mmc: sdhci-msm: drop redundant of_device_id entries

 .../devicetree/bindings/mmc/sdhci-msm.yaml    |  1 +
 arch/arm64/boot/dts/qcom/msm8998.dtsi         |  2 +-
 drivers/mmc/host/sdhci-msm.c                  | 25 -------------------
 3 files changed, 2 insertions(+), 26 deletions(-)

-- 
2.34.1

[PATCH v2 1/3] dt-bindings: mmc: sdhci-msm: add MSM8998

[Krzysztof Kozlowski]

Add a MSM8998-specific SDCC compatible, because using only a generic
qcom,sdhci-msm-v4 fallback is deprecated.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

---

Cc: Konrad Dybcio <konrad.dybcio@somainline.org>
Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>
---
 Documentation/devicetree/bindings/mmc/sdhci-msm.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml b/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
index 31a3ce208e1a..0853d0c32dc7 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
+++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.yaml
@@ -30,6 +30,7 @@ properties:
               - qcom,msm8992-sdhci
               - qcom,msm8994-sdhci
               - qcom,msm8996-sdhci
+              - qcom,msm8998-sdhci
           - const: qcom,sdhci-msm-v4 # for sdcc versions less than 5.0
       - items:
           - enum:
-- 
2.34.1

[PATCH v2 2/3] arm64: dts: qcom: msm8998: add MSM8998 SDCC specific compatible

[Krzysztof Kozlowski]

Add a MSM8998-specific SDCC compatible, because using only a generic
qcom,sdhci-msm-v4 fallback is deprecated.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

---

Cc: Konrad Dybcio <konrad.dybcio@somainline.org>
Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>
---
 arch/arm64/boot/dts/qcom/msm8998.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/msm8998.dtsi b/arch/arm64/boot/dts/qcom/msm8998.dtsi
index 85bbd4f7306d..e263a59d84b0 100644
--- a/arch/arm64/boot/dts/qcom/msm8998.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998.dtsi
@@ -2076,7 +2076,7 @@ qusb2phy: phy@c012000 {
 		};
 
 		sdhc2: mmc@c0a4900 {
-			compatible = "qcom,sdhci-msm-v4";
+			compatible = "qcom,msm8998-sdhci", "qcom,sdhci-msm-v4";
 			reg = <0x0c0a4900 0x314>, <0x0c0a4000 0x800>;
 			reg-names = "hc_mem", "core_mem";
 
-- 
2.34.1

[PATCH v2 3/3] mmc: sdhci-msm: drop redundant of_device_id entries

[Krzysztof Kozlowski]

This reverts three commits:
1. Revert "mmc: sdhci-msm: Add compatible string check for sdx65"
   This reverts commit 953706844f0f2fd4dc6984cc010fe6cf51c041f2.

2. Revert "mmc: sdhci-msm: Add compatible string check for sm8150"
   This reverts commit 5acd6adb65802cc6f9986be3750179a820580d37.

3. Revert "mmc: sdhci-msm: Add SoC specific compatibles"
   This reverts commit 466614a9765c6fb67e1464d0a3f1261db903834b.

The oldest commit 466614a9765c ("mmc: sdhci-msm: Add SoC specific
compatibles") did not specify what benefits such multiple compatibles
bring, therefore assume there is none.  On the other hand such approach
brings a lot of churn to driver maintenance by expecting commit for
every new compatible, even though it is already covered by the fallback.

There is really no sense in duplicating of_device_id for each
variant, which is already covered by generic compatible fallback
qcom,sdhci-msm-v4 or qcom,sdhci-msm-v5.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

---

Cc: Konrad Dybcio <konrad.dybcio@somainline.org>
Cc: Bhupesh Sharma <bhupesh.sharma@linaro.org>
Cc: Doug Anderson <dianders@chromium.org>
---
 drivers/mmc/host/sdhci-msm.c | 25 -------------------------
 1 file changed, 25 deletions(-)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index e395411fb6fd..ff9f5b63c337 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -2435,33 +2435,8 @@ static const struct sdhci_msm_variant_info sdm845_sdhci_var = {
 };
 
 static const struct of_device_id sdhci_msm_dt_match[] = {
-	 /* Following two entries are deprecated (kept only for backward compatibility) */
 	{.compatible = "qcom,sdhci-msm-v4", .data = &sdhci_msm_mci_var},
 	{.compatible = "qcom,sdhci-msm-v5", .data = &sdhci_msm_v5_var},
-	/* Add entries for sdcc versions less than 5.0 here */
-	{.compatible = "qcom,apq8084-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8226-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8916-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8953-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8974-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8992-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8994-sdhci", .data = &sdhci_msm_mci_var},
-	{.compatible = "qcom,msm8996-sdhci", .data = &sdhci_msm_mci_var},
-	/*
-	 * Add entries for sdcc version 5.0 here. For SDCC version 5.0.0,
-	 * MCI registers are removed from SDCC interface and some registers
-	 * are moved to HC.
-	 */
-	{.compatible = "qcom,qcs404-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sdx55-sdhci",  .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sdx65-sdhci",  .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sdm630-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sm6125-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sm6350-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sm8150-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sm8250-sdhci", .data = &sdhci_msm_v5_var},
-	{.compatible = "qcom,sc7280-sdhci", .data = &sdhci_msm_v5_var},
-	/* Add entries where soc specific handling is required, here */
 	{.compatible = "qcom,sdm845-sdhci", .data = &sdm845_sdhci_var},
 	{.compatible = "qcom,sc7180-sdhci", .data = &sdm845_sdhci_var},
 	{},
-- 
2.34.1

Re: [PATCH v2 3/3] mmc: sdhci-msm: drop redundant of_device_id entries

[Doug Anderson]

Hi,

On Tue, Jul 12, 2022 at 8:02 AM Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> This reverts three commits:
> 1. Revert "mmc: sdhci-msm: Add compatible string check for sdx65"
>    This reverts commit 953706844f0f2fd4dc6984cc010fe6cf51c041f2.
>
> 2. Revert "mmc: sdhci-msm: Add compatible string check for sm8150"
>    This reverts commit 5acd6adb65802cc6f9986be3750179a820580d37.
>
> 3. Revert "mmc: sdhci-msm: Add SoC specific compatibles"
>    This reverts commit 466614a9765c6fb67e1464d0a3f1261db903834b.
>
> The oldest commit 466614a9765c ("mmc: sdhci-msm: Add SoC specific
> compatibles") did not specify what benefits such multiple compatibles
> bring, therefore assume there is none.  On the other hand such approach
> brings a lot of churn to driver maintenance by expecting commit for
> every new compatible, even though it is already covered by the fallback.
>
> There is really no sense in duplicating of_device_id for each
> variant, which is already covered by generic compatible fallback
> qcom,sdhci-msm-v4 or qcom,sdhci-msm-v5.
>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Personally, I would have taken the extra step and added a comment in
the code to prevent someone from doing this again. Maybe like this:

/*
 * In the device tree, all boards are required to have _two_ compatible
 * strings listed: a SoC-specific one followed by a more generic one.
 * Normally we can just rely on the generic string, but we always
 * include both so that if we ever find a bug on a specific SoC that
 * we need to workaround (like in sdm845/sc7180) that we can quickly
 * work around it without any changes to the dts.
 */

In any case:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

Re: [PATCH v2 3/3] mmc: sdhci-msm: drop redundant of_device_id entries

[Krzysztof Kozlowski]

On 13/07/2022 17:57, Doug Anderson wrote:
> Hi,
> 
> On Tue, Jul 12, 2022 at 8:02 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> This reverts three commits:
>> 1. Revert "mmc: sdhci-msm: Add compatible string check for sdx65"
>>    This reverts commit 953706844f0f2fd4dc6984cc010fe6cf51c041f2.
>>
>> 2. Revert "mmc: sdhci-msm: Add compatible string check for sm8150"
>>    This reverts commit 5acd6adb65802cc6f9986be3750179a820580d37.
>>
>> 3. Revert "mmc: sdhci-msm: Add SoC specific compatibles"
>>    This reverts commit 466614a9765c6fb67e1464d0a3f1261db903834b.
>>
>> The oldest commit 466614a9765c ("mmc: sdhci-msm: Add SoC specific
>> compatibles") did not specify what benefits such multiple compatibles
>> bring, therefore assume there is none.  On the other hand such approach
>> brings a lot of churn to driver maintenance by expecting commit for
>> every new compatible, even though it is already covered by the fallback.
>>
>> There is really no sense in duplicating of_device_id for each
>> variant, which is already covered by generic compatible fallback
>> qcom,sdhci-msm-v4 or qcom,sdhci-msm-v5.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> Personally, I would have taken the extra step and added a comment in
> the code to prevent someone from doing this again. Maybe like this:
> 
> /*
>  * In the device tree, all boards are required to have _two_ compatible
>  * strings listed: a SoC-specific one followed by a more generic one.
>  * Normally we can just rely on the generic string, but we always
>  * include both so that if we ever find a bug on a specific SoC that
>  * we need to workaround (like in sdm845/sc7180) that we can quickly
>  * work around it without any changes to the dts.
>  */

This actually does not instruct the developer not to add new variants to
the driver, so how about something like:

/* Do not add new variants to the driver which are compatible with
generic ones, unless they need customization. */
?

The problem is that this applies to several such drivers on several
platforms (Qualcomm, NXP - these for sure use such pattern), so we would
be documenting something obvious, IMO.

> 
> In any case:
> 
> Reviewed-by: Douglas Anderson <dianders@chromium.org>


Best regards,
Krzysztof

Re: [PATCH v2 3/3] mmc: sdhci-msm: drop redundant of_device_id entries

[Doug Anderson]

Hi,

On Wed, Jul 13, 2022 at 9:07 AM Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 13/07/2022 17:57, Doug Anderson wrote:
> > Hi,
> >
> > On Tue, Jul 12, 2022 at 8:02 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski@linaro.org> wrote:
> >>
> >> This reverts three commits:
> >> 1. Revert "mmc: sdhci-msm: Add compatible string check for sdx65"
> >>    This reverts commit 953706844f0f2fd4dc6984cc010fe6cf51c041f2.
> >>
> >> 2. Revert "mmc: sdhci-msm: Add compatible string check for sm8150"
> >>    This reverts commit 5acd6adb65802cc6f9986be3750179a820580d37.
> >>
> >> 3. Revert "mmc: sdhci-msm: Add SoC specific compatibles"
> >>    This reverts commit 466614a9765c6fb67e1464d0a3f1261db903834b.
> >>
> >> The oldest commit 466614a9765c ("mmc: sdhci-msm: Add SoC specific
> >> compatibles") did not specify what benefits such multiple compatibles
> >> bring, therefore assume there is none.  On the other hand such approach
> >> brings a lot of churn to driver maintenance by expecting commit for
> >> every new compatible, even though it is already covered by the fallback.
> >>
> >> There is really no sense in duplicating of_device_id for each
> >> variant, which is already covered by generic compatible fallback
> >> qcom,sdhci-msm-v4 or qcom,sdhci-msm-v5.
> >>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >
> > Personally, I would have taken the extra step and added a comment in
> > the code to prevent someone from doing this again. Maybe like this:
> >
> > /*
> >  * In the device tree, all boards are required to have _two_ compatible
> >  * strings listed: a SoC-specific one followed by a more generic one.
> >  * Normally we can just rely on the generic string, but we always
> >  * include both so that if we ever find a bug on a specific SoC that
> >  * we need to workaround (like in sdm845/sc7180) that we can quickly
> >  * work around it without any changes to the dts.
> >  */
>
> This actually does not instruct the developer not to add new variants to
> the driver, so how about something like:
>
> /* Do not add new variants to the driver which are compatible with
> generic ones, unless they need customization. */
> ?

Sure, that would be fine.


> The problem is that this applies to several such drivers on several
> platforms (Qualcomm, NXP - these for sure use such pattern), so we would
> be documenting something obvious, IMO.

The problem is that the people adding to this file are probably not
device tree experts and may not know, so a short comment might be
worthwhile. If you don't think it's a good idea, though, I won't push.

-Doug