[PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Dmitry Baryshkov]

The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
Document qcom board compatible format") never got actually adopted. As
can be seen from the existing board DT files, no device actually used
the PMIC / foundry / version parts of the compatible string. Drop this
compatibility string description to avoid possible confusion and keep
just the generic terms and the SoC list.

Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 Documentation/devicetree/bindings/arm/qcom.yaml | 51 +++----------------------
 1 file changed, 5 insertions(+), 46 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml b/Documentation/devicetree/bindings/arm/qcom.yaml
index 1999a5f2f254..2b993b4c51dc 100644
--- a/Documentation/devicetree/bindings/arm/qcom.yaml
+++ b/Documentation/devicetree/bindings/arm/qcom.yaml
@@ -10,17 +10,10 @@ maintainers:
   - Bjorn Andersson <bjorn.andersson@linaro.org>
 
 description: |
-  Some qcom based bootloaders identify the dtb blob based on a set of
-  device properties like SoC and platform and revisions of those components.
-  To support this scheme, we encode this information into the board compatible
-  string.
-
-  Each board must specify a top-level board compatible string with the following
-  format:
-
-  	compatible = "qcom,<SoC>[-<soc_version>][-<foundry_id>]-<board>[/<subtype>][-<board_version>]"
-
-  The 'SoC' and 'board' elements are required. All other elements are optional.
+  For devices using the Qualcomm SoC the "compatible" properties consists of
+  one or several "manufacturer,model" strings, describing the device itself,
+  followed by one or several "qcom,<SoC>" strings, describing the SoC used in
+  the device.
 
   The 'SoC' element must be one of the following strings:
 
@@ -90,43 +83,9 @@ description: |
         sm8650
         x1e80100
 
-  The 'board' element must be one of the following strings:
-
-        adp
-        cdp
-        dragonboard
-        idp
-        liquid
-        mtp
-        qcp
-        qrd
-        rb2
-        ride
-        sbc
-        x100
-
-  The 'soc_version' and 'board_version' elements take the form of v<Major>.<Minor>
-  where the minor number may be omitted when it's zero, i.e.  v1.0 is the same
-  as v1. If all versions of the 'board_version' elements match, then a
-  wildcard '*' should be used, e.g. 'v*'.
-
-  The 'foundry_id' and 'subtype' elements are one or more digits from 0 to 9.
-
-  Examples:
-
-  	"qcom,msm8916-v1-cdp-pm8916-v2.1"
-
-  A CDP board with an msm8916 SoC, version 1 paired with a pm8916 PMIC of version
-  2.1.
-
-  	"qcom,apq8074-v2.0-2-dragonboard/1-v0.1"
-
-  A dragonboard board v0.1 of subtype 1 with an apq8074 SoC version 2, made in
-  foundry 2.
-
   There are many devices in the list below that run the standard ChromeOS
   bootloader setup and use the open source depthcharge bootloader to boot the
-  OS. These devices do not use the scheme described above. For details, see:
+  OS. These devices use the bootflow explained at
   https://docs.kernel.org/arch/arm/google/chromebook-boot-flow.html
 
 properties:

---
base-commit: 076d56d74f17e625b3d63cf4743b3d7d02180379
change-id: 20240204-qcom-drop-compat-6c21c9e1f907

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Krzysztof Kozlowski]

On 04/02/2024 17:56, Dmitry Baryshkov wrote:
> The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> Document qcom board compatible format") never got actually adopted. As
> can be seen from the existing board DT files, no device actually used
> the PMIC / foundry / version parts of the compatible string. Drop this
> compatibility string description to avoid possible confusion and keep
> just the generic terms and the SoC list.
> 
> Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  Documentation/devicetree/bindings/arm/qcom.yaml | 51 +++----------------------
>  1 file changed, 5 insertions(+), 46 deletions(-)
> 

Maybe not necessarily fix, but anyway:

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

Best regards,
Krzysztof

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Bjorn Andersson]

On Sun, Feb 04, 2024 at 06:56:35PM +0200, Dmitry Baryshkov wrote:
> The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> Document qcom board compatible format") never got actually adopted. As
> can be seen from the existing board DT files, no device actually used
> the PMIC / foundry / version parts of the compatible string. Drop this
> compatibility string description to avoid possible confusion and keep
> just the generic terms and the SoC list.
> 
> Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Bjorn Andersson]

On Sun, 04 Feb 2024 18:56:35 +0200, Dmitry Baryshkov wrote:
> The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> Document qcom board compatible format") never got actually adopted. As
> can be seen from the existing board DT files, no device actually used
> the PMIC / foundry / version parts of the compatible string. Drop this
> compatibility string description to avoid possible confusion and keep
> just the generic terms and the SoC list.
> 
> [...]

Applied, thanks!

[1/1] dt-bindings: arm: qcom: drop the superfluous device compatibility schema
      commit: 869c3d4eef65f3daf2f7a3a4155655f76a11eb87

Best regards,
-- 
Bjorn Andersson <andersson@kernel.org>

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Stephan Gerhold]

On Sun, Feb 04, 2024 at 06:56:35PM +0200, Dmitry Baryshkov wrote:
> The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> Document qcom board compatible format") never got actually adopted. As
> can be seen from the existing board DT files, no device actually used
> the PMIC / foundry / version parts of the compatible string. Drop this
> compatibility string description to avoid possible confusion and keep
> just the generic terms and the SoC list.
> 
> Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")

FWIW: It's not correct that no device uses the version parts of the
compatible string. There are actually two boards documented in qcom.yaml
that follow this scheme:

  compatible = "qcom,msm8916-mtp", "qcom,msm8916-mtp/1", "qcom,msm8916";
  compatible = "longcheer,l8150", "qcom,msm8916-v1-qrd/9-v1", "qcom,msm8916";

I don't think anyone is actively relying on those, though. I guess we
can just ignore them or even remove them.

Thanks,
Stephan

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Dmitry Baryshkov]

On Sun, 11 Feb 2024 at 12:36, Stephan Gerhold <stephan@gerhold.net> wrote:
>
> On Sun, Feb 04, 2024 at 06:56:35PM +0200, Dmitry Baryshkov wrote:
> > The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> > Document qcom board compatible format") never got actually adopted. As
> > can be seen from the existing board DT files, no device actually used
> > the PMIC / foundry / version parts of the compatible string. Drop this
> > compatibility string description to avoid possible confusion and keep
> > just the generic terms and the SoC list.
> >
> > Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
>
> FWIW: It's not correct that no device uses the version parts of the
> compatible string. There are actually two boards documented in qcom.yaml
> that follow this scheme:
>
>   compatible = "qcom,msm8916-mtp", "qcom,msm8916-mtp/1", "qcom,msm8916";
>   compatible = "longcheer,l8150", "qcom,msm8916-v1-qrd/9-v1", "qcom,msm8916";
>
> I don't think anyone is actively relying on those, though. I guess we
> can just ignore them or even remove them.

Excuse me for the long delay. As it was you who added the
longcheer-l8150 support, does it require any of the msm-id options or
dtbTool (original or modified) processing?
If it can work with no additional tags, we can drop these compatibility strings.

-- 
With best wishes
Dmitry

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Stephan Gerhold]

On Tue, Feb 20, 2024 at 11:11:15AM +0200, Dmitry Baryshkov wrote:
> On Sun, 11 Feb 2024 at 12:36, Stephan Gerhold <stephan@gerhold.net> wrote:
> > On Sun, Feb 04, 2024 at 06:56:35PM +0200, Dmitry Baryshkov wrote:
> > > The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> > > Document qcom board compatible format") never got actually adopted. As
> > > can be seen from the existing board DT files, no device actually used
> > > the PMIC / foundry / version parts of the compatible string. Drop this
> > > compatibility string description to avoid possible confusion and keep
> > > just the generic terms and the SoC list.
> > >
> > > Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
> >
> > FWIW: It's not correct that no device uses the version parts of the
> > compatible string. There are actually two boards documented in qcom.yaml
> > that follow this scheme:
> >
> >   compatible = "qcom,msm8916-mtp", "qcom,msm8916-mtp/1", "qcom,msm8916";
> >   compatible = "longcheer,l8150", "qcom,msm8916-v1-qrd/9-v1", "qcom,msm8916";
> >
> > I don't think anyone is actively relying on those, though. I guess we
> > can just ignore them or even remove them.
> 
> Excuse me for the long delay. As it was you who added the
> longcheer-l8150 support, does it require any of the msm-id options or
> dtbTool (original or modified) processing?
> If it can work with no additional tags, we can drop these compatibility strings.
> 

I think we added it back then to allow booting mainline with the
original bootloader. Together with the "skales" dtbTool (used to be at
https://source.codeaurora.org/quic/kernel/skales) the compatible does
result in a correct QCDT that is accepted by the bootloader.

I doubt anyone still uses this way of booting nowadays. In postmarketOS
we strongly recommend everyone to boot MSM8916 devices using lk2nd [1]
which supports plain appended DTB without special properties and other
more reliable forms of DTB selection. I have not tested booting mainline
with the original bootloader for many years.

Dropping the extra compatible would be fine for me. Personally I don't
consider booting via weird/broken bootloaders worth supporting (at least
if better workarounds exist). Having to boot with "custom" bootloaders
tends to be a somewhat subjective topic though so others might disagree.

Thanks,
Stephan

[1]: https://github.com/msm8916-mainline/lk2nd

Re: [PATCH] dt-bindings: arm: qcom: drop the superfluous device compatibility schema

[Dmitry Baryshkov]

On Tue, 20 Feb 2024 at 23:11, Stephan Gerhold <stephan@gerhold.net> wrote:
>
> On Tue, Feb 20, 2024 at 11:11:15AM +0200, Dmitry Baryshkov wrote:
> > On Sun, 11 Feb 2024 at 12:36, Stephan Gerhold <stephan@gerhold.net> wrote:
> > > On Sun, Feb 04, 2024 at 06:56:35PM +0200, Dmitry Baryshkov wrote:
> > > > The idea impressed in the commit b32e592d3c28 ("devicetree: bindings:
> > > > Document qcom board compatible format") never got actually adopted. As
> > > > can be seen from the existing board DT files, no device actually used
> > > > the PMIC / foundry / version parts of the compatible string. Drop this
> > > > compatibility string description to avoid possible confusion and keep
> > > > just the generic terms and the SoC list.
> > > >
> > > > Fixes: b32e592d3c28 ("devicetree: bindings: Document qcom board compatible format")
> > >
> > > FWIW: It's not correct that no device uses the version parts of the
> > > compatible string. There are actually two boards documented in qcom.yaml
> > > that follow this scheme:
> > >
> > >   compatible = "qcom,msm8916-mtp", "qcom,msm8916-mtp/1", "qcom,msm8916";
> > >   compatible = "longcheer,l8150", "qcom,msm8916-v1-qrd/9-v1", "qcom,msm8916";
> > >
> > > I don't think anyone is actively relying on those, though. I guess we
> > > can just ignore them or even remove them.
> >
> > Excuse me for the long delay. As it was you who added the
> > longcheer-l8150 support, does it require any of the msm-id options or
> > dtbTool (original or modified) processing?
> > If it can work with no additional tags, we can drop these compatibility strings.
> >
>
> I think we added it back then to allow booting mainline with the
> original bootloader. Together with the "skales" dtbTool (used to be at
> https://source.codeaurora.org/quic/kernel/skales) the compatible does
> result in a correct QCDT that is accepted by the bootloader.
>
> I doubt anyone still uses this way of booting nowadays. In postmarketOS
> we strongly recommend everyone to boot MSM8916 devices using lk2nd [1]
> which supports plain appended DTB without special properties and other
> more reliable forms of DTB selection. I have not tested booting mainline
> with the original bootloader for many years.

If I remember correctly, if somebody wants to boot msm8916 with the
'original' bootloader, they will also face issues with SMP support,
etc. So let's drop that.

> Dropping the extra compatible would be fine for me. Personally I don't
> consider booting via weird/broken bootloaders worth supporting (at least
> if better workarounds exist). Having to boot with "custom" bootloaders
> tends to be a somewhat subjective topic though so others might disagree.

I usually prefer to stick to the original as much as possible,
especially for the end-user devices. But in this case I think it's
beyond possible.

-- 
With best wishes
Dmitry