[PATCH v2 0/2] arm64: dts: qcom: sm8[56]50: correct MDSS interconnects

[PATCH v2 0/2] arm64: dts: qcom: sm8[56]50: correct MDSS interconnects

[Dmitry Baryshkov]

Both SM8550 and SM8650 misuse mdp1-mem interconnect path for the
LLCC->EBI path, while it should only be used for the MDP->EBI paths.

This kind of misuse can result in bandwidth underflows, possibly
degrading picture quality as the required memory bandwidth is divided
between all mdpN-mem paths (and LLCC-EBI should not be a part of such
division).

Drop mdp1-mem paths and use MDP-EBI path directly.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
Changes in v2:
- Fixed type in 'degrading' in the commit messages (Konrad)
- Link to v1: https://lore.kernel.org/r/20241008-fix-sm8x50-mdp-icc-v1-0-77ffd361b8de@linaro.org

---
Dmitry Baryshkov (2):
      arm64: dts: qcom: sm8550: correct MDSS interconnects
      arm64: dts: qcom: sm8650: correct MDSS interconnects

 arch/arm64/boot/dts/qcom/sm8550.dtsi | 5 ++---
 arch/arm64/boot/dts/qcom/sm8650.dtsi | 5 +----
 2 files changed, 3 insertions(+), 7 deletions(-)
---
base-commit: 7f773fd61baa9b136faa5c4e6555aa64c758d07c
change-id: 20241006-fix-sm8x50-mdp-icc-138afd0e083a

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

[PATCH v2 1/2] arm64: dts: qcom: sm8550: correct MDSS interconnects

[Dmitry Baryshkov]

SM8550 lists two interconnects for the display subsystem, mdp0-mem
(between MDP and LLCC) and mdp1-mem (between LLCC and EBI, memory).
The second interconnect is a misuse. mdpN-mem paths should be used for
several outboud MDP interconnects rather than the path between LLCC and
memory. This kind of misuse can result in bandwidth underflows, possibly
degrading picture quality as the required memory bandwidth is divided
between all mdpN-mem paths (and LLCC-EBI should not be a part of such
division).

Drop the second path and use direct MDP-EBI path for mdp0-mem until we
support separate MDP-LLCC and LLCC-EBI paths.

Fixes: d7da51db5b81 ("arm64: dts: qcom: sm8550: add display hardware devices")
Cc: stable@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 arch/arm64/boot/dts/qcom/sm8550.dtsi | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sm8550.dtsi b/arch/arm64/boot/dts/qcom/sm8550.dtsi
index 9dc0ee3eb98f..cca10f9faa14 100644
--- a/arch/arm64/boot/dts/qcom/sm8550.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8550.dtsi
@@ -2871,9 +2871,8 @@ mdss: display-subsystem@ae00000 {
 
 			power-domains = <&dispcc MDSS_GDSC>;
 
-			interconnects = <&mmss_noc MASTER_MDP 0 &gem_noc SLAVE_LLCC 0>,
-					<&mc_virt MASTER_LLCC 0 &mc_virt SLAVE_EBI1 0>;
-			interconnect-names = "mdp0-mem", "mdp1-mem";
+			interconnects = <&mmss_noc MASTER_MDP 0 &mc_virt SLAVE_EBI1 0>;
+			interconnect-names = "mdp0-mem";
 
 			iommus = <&apps_smmu 0x1c00 0x2>;
 

-- 
2.39.5

Re: [PATCH v2 1/2] arm64: dts: qcom: sm8550: correct MDSS interconnects

[Konrad Dybcio]

On 26.10.2024 7:59 PM, Dmitry Baryshkov wrote:
> SM8550 lists two interconnects for the display subsystem, mdp0-mem
> (between MDP and LLCC) and mdp1-mem (between LLCC and EBI, memory).
> The second interconnect is a misuse. mdpN-mem paths should be used for
> several outboud MDP interconnects rather than the path between LLCC and
> memory. This kind of misuse can result in bandwidth underflows, possibly
> degrading picture quality as the required memory bandwidth is divided
> between all mdpN-mem paths (and LLCC-EBI should not be a part of such
> division).
> 
> Drop the second path and use direct MDP-EBI path for mdp0-mem until we
> support separate MDP-LLCC and LLCC-EBI paths.
> 
> Fixes: d7da51db5b81 ("arm64: dts: qcom: sm8550: add display hardware devices")
> Cc: stable@kernel.org
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---

Feel free to use QCOM_ICC_TAG_ALWAYS, for both patches:

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

[PATCH v2 2/2] arm64: dts: qcom: sm8650: correct MDSS interconnects

[Dmitry Baryshkov]

SM8650 lists two interconnects for the display subsystem, mdp0-mem
(between MDP and LLCC) and mdp1-mem (between LLCC and EBI, memory).
The second interconnect is a misuse. mdpN-mem paths should be used for
several outboud MDP interconnects rather than the path between LLCC and
memory. This kind of misuse can result in bandwidth underflows, possibly
degrading picture quality as the required memory bandwidth is divided
between all mdpN-mem paths (and LLCC-EBI should not be a part of such
division).

Drop the second path and use direct MDP-EBI path for mdp0-mem until we
support separate MDP-LLCC and LLCC-EBI paths.

Fixes: 10e024671295 ("arm64: dts: qcom: sm8650: add interconnect dependent device nodes")
Cc: stable@kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 arch/arm64/boot/dts/qcom/sm8650.dtsi | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sm8650.dtsi b/arch/arm64/boot/dts/qcom/sm8650.dtsi
index 173e092b15e2..4b54063c0e0c 100644
--- a/arch/arm64/boot/dts/qcom/sm8650.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8650.dtsi
@@ -3455,11 +3455,8 @@ mdss: display-subsystem@ae00000 {
 			resets = <&dispcc DISP_CC_MDSS_CORE_BCR>;
 
 			interconnects = <&mmss_noc MASTER_MDP QCOM_ICC_TAG_ALWAYS
-					 &gem_noc SLAVE_LLCC QCOM_ICC_TAG_ALWAYS>,
-					<&mc_virt MASTER_LLCC QCOM_ICC_TAG_ALWAYS
 					 &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_ALWAYS>;
-			interconnect-names = "mdp0-mem",
-					     "mdp1-mem";
+			interconnect-names = "mdp0-mem";
 
 			power-domains = <&dispcc MDSS_GDSC>;
 

-- 
2.39.5

Re: [PATCH v2 2/2] arm64: dts: qcom: sm8650: correct MDSS interconnects

[Neil Armstrong]

On 26/10/2024 19:59, Dmitry Baryshkov wrote:
> SM8650 lists two interconnects for the display subsystem, mdp0-mem
> (between MDP and LLCC) and mdp1-mem (between LLCC and EBI, memory).
> The second interconnect is a misuse. mdpN-mem paths should be used for
> several outboud MDP interconnects rather than the path between LLCC and
> memory. This kind of misuse can result in bandwidth underflows, possibly
> degrading picture quality as the required memory bandwidth is divided
> between all mdpN-mem paths (and LLCC-EBI should not be a part of such
> division).
> 
> Drop the second path and use direct MDP-EBI path for mdp0-mem until we
> support separate MDP-LLCC and LLCC-EBI paths.
> 
> Fixes: 10e024671295 ("arm64: dts: qcom: sm8650: add interconnect dependent device nodes")
> Cc: stable@kernel.org
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>   arch/arm64/boot/dts/qcom/sm8650.dtsi | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sm8650.dtsi b/arch/arm64/boot/dts/qcom/sm8650.dtsi
> index 173e092b15e2..4b54063c0e0c 100644
> --- a/arch/arm64/boot/dts/qcom/sm8650.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sm8650.dtsi
> @@ -3455,11 +3455,8 @@ mdss: display-subsystem@ae00000 {
>   			resets = <&dispcc DISP_CC_MDSS_CORE_BCR>;
>   
>   			interconnects = <&mmss_noc MASTER_MDP QCOM_ICC_TAG_ALWAYS
> -					 &gem_noc SLAVE_LLCC QCOM_ICC_TAG_ALWAYS>,
> -					<&mc_virt MASTER_LLCC QCOM_ICC_TAG_ALWAYS
>   					 &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_ALWAYS>;
> -			interconnect-names = "mdp0-mem",
> -					     "mdp1-mem";
> +			interconnect-names = "mdp0-mem";
>   
>   			power-domains = <&dispcc MDSS_GDSC>;
>   
> 

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH v2 0/2] arm64: dts: qcom: sm8[56]50: correct MDSS interconnects

[Bjorn Andersson]

On Sat, 26 Oct 2024 20:59:39 +0300, Dmitry Baryshkov wrote:
> Both SM8550 and SM8650 misuse mdp1-mem interconnect path for the
> LLCC->EBI path, while it should only be used for the MDP->EBI paths.
> 
> This kind of misuse can result in bandwidth underflows, possibly
> degrading picture quality as the required memory bandwidth is divided
> between all mdpN-mem paths (and LLCC-EBI should not be a part of such
> division).
> 
> [...]

Applied, thanks!

[1/2] arm64: dts: qcom: sm8550: correct MDSS interconnects
      commit: b8591df49cde459e3b84cdc0517d7bf92053d244
[2/2] arm64: dts: qcom: sm8650: correct MDSS interconnects
      commit: 9fa33cbca3d2842f1f47ed4e5f6574e611dae32b

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