From: Petr Hodina <petr.hodina@protonmail.com>

Currently the panel driver for tianma is broken.
Disable MDSS to prevent DRM taking over the framebuffer.

Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
index b58964cde8342..d1c7bccaab500 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
+++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
@@ -36,3 +36,13 @@ touchscreen@1 {
 		touchscreen-size-y = <2246>;
 	};
 };
+
+&dispcc {
+	/* Disable for now so simple-framebuffer continues working */
+	status = "disabled";
+};
+
+&mdss {
+	/* Disable for now so simple-framebuffer continues working */
+	status = "disabled";
+};

-- 
2.53.0

On Tue, Mar 17, 2026 at 11:12:35PM +0100, David Heidelberg via B4 Relay wrote:
> From: Petr Hodina <petr.hodina@protonmail.com>
> 
> Currently the panel driver for tianma is broken.
> Disable MDSS to prevent DRM taking over the framebuffer.

I'd still hope that somebody can get it to work. I'd start by using
prepare_prev_first. Sumit reported the panel as working in 2020 and I
have no doubts that it was the case. Another option migt be something
related to the dispcc (see my [1]).

[1] https://lore.kernel.org/linux-arm-msm/20260217-sdm845-hdk-v1-1-866f1965fef7@oss.qualcomm.com/

> 
> Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
> index b58964cde8342..d1c7bccaab500 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
> +++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts
> @@ -36,3 +36,13 @@ touchscreen@1 {
>  		touchscreen-size-y = <2246>;
>  	};
>  };
> +
> +&dispcc {
> +	/* Disable for now so simple-framebuffer continues working */
> +	status = "disabled";
> +};
> +
> +&mdss {
> +	/* Disable for now so simple-framebuffer continues working */
> +	status = "disabled";
> +};
> 
> -- 
> 2.53.0
> 
> 

-- 
With best wishes
Dmitry

On 18/03/2026 15:47, Dmitry Baryshkov wrote:
> On Tue, Mar 17, 2026 at 11:12:35PM +0100, David Heidelberg via B4 Relay wrote:
>> From: Petr Hodina <petr.hodina@protonmail.com>
>>
>> Currently the panel driver for tianma is broken.
>> Disable MDSS to prevent DRM taking over the framebuffer.
> 
> I'd still hope that somebody can get it to work. I'd start by using
> prepare_prev_first. Sumit reported the panel as working in 2020 and I
> have no doubts that it was the case. Another option migt be something
> related to the dispcc (see my [1]).

It's probable that prepare_prev_first will help, just sending the patchas part 
of the original series.

I'm completely fine with taking other commits and leaving this one after more 
investigation.

David

> 
> [1] https://lore.kernel.org/linux-arm-msm/20260217-sdm845-hdk-v1-1-866f1965fef7@oss.qualcomm.com/
>