[PATCH v6 1/2] dt-bindings: display/msm: mdss-common: add memory-region property

[PATCH v6 1/2] dt-bindings: display/msm: mdss-common: add memory-region property

[Amit Pundir]

Add and document the reserved memory region property in the
mdss-common schema.

For now (sdm845-db845c), it points to a framebuffer memory
region reserved by the bootloader for splash screen.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
---
v6: Re-sending with review and ack tags. Ideally this
    dt-binding patch should be marked for stable as well,
    like the follow-up sdm845-db845c.dts patch in the series
    but it can't be cherry picked cleanly on older LTS
    versions. I can do it separately if it is required.

v5: Moving the dt-binding to mdss-common schema with
    updated commit message and property description.

v4: Adding this new dt-binding patch, in qcom,sdm845-mdss
    schema, in the v4 of the follow-up patch for
    sdm845-db845c.
    https://lore.kernel.org/lkml/20230712130215.666924-2-amit.pundir@linaro.org/

 .../devicetree/bindings/display/msm/mdss-common.yaml         | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/msm/mdss-common.yaml b/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
index ccd7d6417523..84ed2757ded5 100644
--- a/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
+++ b/Documentation/devicetree/bindings/display/msm/mdss-common.yaml
@@ -77,6 +77,12 @@ properties:
     items:
       - description: MDSS_CORE reset
 
+  memory-region:
+    maxItems: 1
+    description:
+      Phandle to a node describing a reserved framebuffer memory region.
+      For example, the splash memory region set up by the bootloader.
+
 required:
   - reg
   - reg-names
-- 
2.25.1

[PATCH v6 2/2] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

[Amit Pundir]

Adding a reserved memory region for the framebuffer memory
(the splash memory region set up by the bootloader).

It fixes a kernel panic (arm-smmu: Unhandled context fault
at this particular memory region) reported on DB845c running
v5.10.y.

Cc: stable@vger.kernel.org # v5.10+
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
---
v6: Collected review tag, updated commit message for the
    context and marked for stable kernel versions.

v5: Re-sending with updated dt-bindings patch in mdss-common
    schema.

v4: Re-sending this along with a new dt-bindings patch to
    document memory-region property in qcom,sdm845-mdss
    schema and keep dtbs_check happy.

v3: Point this reserved region to MDSS.

v2: Updated commit message.

There was some dicussion on v1 but it didn't go anywhere,
https://lore.kernel.org/linux-kernel/20230124182857.1524912-1-amit.pundir@linaro.org/T/#u.
The general consensus is that this memory should be freed and be
made resuable but that (releasing this piece of memory) has been
tried before and it is not trivial to return the reserved memory
node to the system RAM pool in this case.

 arch/arm64/boot/dts/qcom/sdm845-db845c.dts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
index d6b464cb61d6..f546f6f57c1e 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
+++ b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
@@ -101,6 +101,14 @@ hdmi_con: endpoint {
 		};
 	};
 
+	reserved-memory {
+		/* Cont splash region set up by the bootloader */
+		cont_splash_mem: framebuffer@9d400000 {
+			reg = <0x0 0x9d400000 0x0 0x2400000>;
+			no-map;
+		};
+	};
+
 	lt9611_1v8: lt9611-vdd18-regulator {
 		compatible = "regulator-fixed";
 		regulator-name = "LT9611_1V8";
@@ -506,6 +514,7 @@ &i2c14 {
 };
 
 &mdss {
+	memory-region = <&cont_splash_mem>;
 	status = "okay";
 };
 
-- 
2.25.1

Re: [PATCH v6 2/2] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

[Krzysztof Kozlowski]

On 26/07/2023 15:27, Amit Pundir wrote:
> Adding a reserved memory region for the framebuffer memory
> (the splash memory region set up by the bootloader).
> 
> It fixes a kernel panic (arm-smmu: Unhandled context fault
> at this particular memory region) reported on DB845c running
> v5.10.y.
> 
> Cc: stable@vger.kernel.org # v5.10+
> Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
> Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
> ---


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

Best regards,
Krzysztof

Re: [PATCH v6 1/2] dt-bindings: display/msm: mdss-common: add memory-region property

[Dmitry Baryshkov]

On Wed, 26 Jul 2023 18:57:18 +0530, Amit Pundir wrote:
> Add and document the reserved memory region property in the
> mdss-common schema.
> 
> For now (sdm845-db845c), it points to a framebuffer memory
> region reserved by the bootloader for splash screen.
> 
> 
> [...]

Applied, thanks!

[1/2] dt-bindings: display/msm: mdss-common: add memory-region property
      https://gitlab.freedesktop.org/lumag/msm/-/commit/b4b405040689

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

Re: (subset) [PATCH v6 1/2] dt-bindings: display/msm: mdss-common: add memory-region property

[Bjorn Andersson]

On Wed, 26 Jul 2023 18:57:18 +0530, Amit Pundir wrote:
> Add and document the reserved memory region property in the
> mdss-common schema.
> 
> For now (sdm845-db845c), it points to a framebuffer memory
> region reserved by the bootloader for splash screen.
> 
> 
> [...]

Applied, thanks!

[2/2] arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved
      commit: 110e70fccce4f22b53986ae797d665ffb1950aa6

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