[PATCH v2 0/5] Add framebuffer on Xiaomi Poco F1 and disable the MDSS on tianma panel variant

[PATCH v2 0/5] Add framebuffer on Xiaomi Poco F1 and disable the MDSS on tianma panel variant

[David Heidelberg via B4 Relay]

Enable framebuffer for early console output.

Due to broken panel driver on tianma and no visual output it's better
to disable the MDSS so the framebuffer stays on. 

In case second patch gets rejected, please apply the first one standalone

Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
---
Changes in v2:
- Added few conversion to use memory-region.
- Corrected framebuffer node name. (Konrad)
- Link to v1: https://lore.kernel.org/r/20260311-beryllium-fb-v1-0-408a580d125e@ixit.cz

---
David Heidelberg (3):
      arm64: dts: qcom: sdm845-oneplus: Drop address from framebuffer node
      arm64: dts: qcom: sdm845-shift-axolotl: Convert fb to use memory-region
      arm64: dts: qcom: sdm845-samsung-starqltechn: Convert fb to use memory-region

Petr Hodina (2):
      arm64: dts: qcom: sdm845-xiaomi-beryllium: Introduce framebuffer
      arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

 arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi      |  2 +-
 arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts  |  7 ++++---
 arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts        |  6 +++---
 .../boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi    | 16 ++++++++++++++++
 .../boot/dts/qcom/sdm845-xiaomi-beryllium-tianma.dts     | 10 ++++++++++
 5 files changed, 34 insertions(+), 7 deletions(-)
---
base-commit: 8e5a478b6d6a5bb0a3d52147862b15e4d826af19
change-id: 20260107-beryllium-fb-d3e87bc20be0

Best regards,
-- 
David Heidelberg <david@ixit.cz>

[PATCH v2 1/5] arm64: dts: qcom: sdm845-xiaomi-beryllium: Introduce framebuffer

[David Heidelberg via B4 Relay]

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

Add framebuffer for early console and u-boot support.

Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 .../boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
index 01b570d0880d6..b928100f6464b 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
+++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
@@ -39,6 +39,22 @@ aliases {
 		serial1 = &uart6;
 	};
 
+	chosen {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		framebuffer: framebuffer-0 {
+			compatible = "simple-framebuffer";
+			memory-region = <&cont_splash_mem>;
+
+			format = "a8r8g8b8";
+			stride = <(1080 * 4)>;
+			height = <2246>;
+			width = <1080>;
+		};
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys";
 		autorepeat;

-- 
2.53.0

[PATCH v2 2/5] arm64: dts: qcom: sdm845-oneplus: Drop address from framebuffer node

[David Heidelberg via B4 Relay]

From: David Heidelberg <david@ixit.cz>

This node has no 'reg' property, so it shouldn't have a unit address
(after '@') either

Fixes: b0d5c96e860c ("arm64: dts: qcom: sdm845-oneplus: Add framebuffer")
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
index 5b121ea5520f5..f5fd213d4a1fd 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
+++ b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
@@ -37,7 +37,7 @@ chosen {
 
 		stdout-path = "serial0:115200n8";
 
-		framebuffer: framebuffer@9d400000 {
+		framebuffer: framebuffer-0 {
 			compatible = "simple-framebuffer";
 			memory-region = <&cont_splash_mem>;
 

-- 
2.53.0

[PATCH v2 3/5] arm64: dts: qcom: sdm845-shift-axolotl: Convert fb to use memory-region

[David Heidelberg via B4 Relay]

From: David Heidelberg <david@ixit.cz>

Instead of manually specifying reg, reuse the memory region.

Signed-off-by: David Heidelberg <david@ixit.cz>
---
 arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts b/arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts
index 51b041f91d3e2..27a0facd174c8 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts
+++ b/arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts
@@ -36,9 +36,9 @@ chosen {
 		stdout-path = "serial0";
 
 		/* Use framebuffer setup by the bootloader. */
-		framebuffer0: framebuffer@9d400000 {
+		framebuffer0: framebuffer-0 {
 			compatible = "simple-framebuffer";
-			reg = <0x0 0x9d400000 0x0 (1080 * 2160 * 4)>;
+			memory-region = <&framebuffer_mem>;
 			width = <1080>;
 			height = <2160>;
 			stride = <(1080 * 4)>;
@@ -62,7 +62,7 @@ key-vol-up {
 	};
 
 	reserved-memory {
-		framebuffer@9d400000 {
+		framebuffer_mem: framebuffer@9d400000 {
 			reg = <0x0 0x9d400000 0x0 (1080 * 2160 * 4)>;
 			no-map;
 		};

-- 
2.53.0

[PATCH v2 4/5] arm64: dts: qcom: sdm845-samsung-starqltechn: Convert fb to use memory-region

[David Heidelberg via B4 Relay]

From: David Heidelberg <david@ixit.cz>

Instead of manually specifying reg, reuse the memory region.

Signed-off-by: David Heidelberg <david@ixit.cz>
---
 arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts b/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
index 77f5872de6f19..e704497853407 100644
--- a/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
+++ b/arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts
@@ -43,9 +43,10 @@ chosen {
 		#address-cells = <2>;
 		#size-cells = <2>;
 		ranges;
-		framebuffer: framebuffer@9d400000 {
+
+		framebuffer: framebuffer-0 {
 			compatible = "simple-framebuffer";
-			reg = <0 0x9d400000 0 (2960 * 1440 * 4)>;//2400000
+			memory-region = <&framebuffer_mem>;
 			width = <1440>;
 			height = <2960>;
 			stride = <(1440 * 4)>;
@@ -109,7 +110,7 @@ vreg_s4a_1p8: pm8998-smps4 {
 	};
 
 	reserved-memory {
-		memory@9d400000 {
+		framebuffer_mem: memory@9d400000 {
 			reg = <0x0 0x9d400000 0x0 0x02400000>;
 			no-map;
 		};

-- 
2.53.0

[PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[David Heidelberg via B4 Relay]

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

Re: [PATCH v2 1/5] arm64: dts: qcom: sdm845-xiaomi-beryllium: Introduce framebuffer

[Konrad Dybcio]

On 3/17/26 11:12 PM, David Heidelberg via B4 Relay wrote:
> From: Petr Hodina <petr.hodina@protonmail.com>
> 
> Add framebuffer for early console and u-boot support.
> 
> Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  .../boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi    | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> index 01b570d0880d6..b928100f6464b 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> @@ -39,6 +39,22 @@ aliases {
>  		serial1 = &uart6;
>  	};
>  
> +	chosen {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		framebuffer: framebuffer-0 {

If you don't expect more framebuffers in the future, just 'framebuffer'
for the name is OK

Konrad

Re: [PATCH v2 1/5] arm64: dts: qcom: sdm845-xiaomi-beryllium: Introduce framebuffer

[Konrad Dybcio]

On 3/17/26 11:12 PM, David Heidelberg via B4 Relay wrote:
> From: Petr Hodina <petr.hodina@protonmail.com>
> 
> Add framebuffer for early console and u-boot support.
> 
> Signed-off-by: Petr Hodina <petr.hodina@protonmail.com>
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  .../boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi    | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> index 01b570d0880d6..b928100f6464b 100644
> --- a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi
> @@ -39,6 +39,22 @@ aliases {
>  		serial1 = &uart6;
>  	};
>  
> +	chosen {
> +		#address-cells = <2>;
> +		#size-cells = <2>;
> +		ranges;
> +
> +		framebuffer: framebuffer-0 {

Also if the label is unused, let's drop it

Konrad

Re: [PATCH v2 2/5] arm64: dts: qcom: sdm845-oneplus: Drop address from framebuffer node

[Dmitry Baryshkov]

On Tue, Mar 17, 2026 at 11:12:32PM +0100, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david@ixit.cz>
> 
> This node has no 'reg' property, so it shouldn't have a unit address
> (after '@') either
> 
> Fixes: b0d5c96e860c ("arm64: dts: qcom: sdm845-oneplus: Add framebuffer")
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

-- 
With best wishes
Dmitry

Re: [PATCH v2 3/5] arm64: dts: qcom: sdm845-shift-axolotl: Convert fb to use memory-region

[Dmitry Baryshkov]

On Tue, Mar 17, 2026 at 11:12:33PM +0100, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david@ixit.cz>
> 
> Instead of manually specifying reg, reuse the memory region.
> 
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  arch/arm64/boot/dts/qcom/sdm845-shift-axolotl.dts | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v2 4/5] arm64: dts: qcom: sdm845-samsung-starqltechn: Convert fb to use memory-region

[Dmitry Baryshkov]

On Tue, Mar 17, 2026 at 11:12:34PM +0100, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david@ixit.cz>
> 
> Instead of manually specifying reg, reuse the memory region.
> 
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  arch/arm64/boot/dts/qcom/sdm845-samsung-starqltechn.dts | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[Dmitry Baryshkov]

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

Re: [PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[David Heidelberg]

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/
> 

Re: [PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[David Heidelberg]

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]).

Sadly, the prepare_prev_first didn't solve the issue. The framebuffer -> MDSS 
takover happens, but at greetd (login) loading screen goes black and never restores.

Will need more work.

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

Re: [PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[Dmitry Baryshkov]

On Fri, Apr 10, 2026 at 03:51:12PM +0200, David Heidelberg wrote:
> 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]).
> 
> Sadly, the prepare_prev_first didn't solve the issue. The framebuffer ->
> MDSS takover happens, but at greetd (login) loading screen goes black and
> never restores.
> 
> Will need more work.

Do you see a console _while_ it boots, after the handover? I'd check the
mode programming. Maybe, disabling panel reset would also (temporarily)
help.

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

-- 
With best wishes
Dmitry

Re: [PATCH v2 5/5] arm64: dts: qcom: sdm845-xiaomi-beryllium-tianma: Disable MDSS

[David Heidelberg]

On 12/04/2026 02:36, Dmitry Baryshkov wrote:
> On Fri, Apr 10, 2026 at 03:51:12PM +0200, David Heidelberg wrote:
>> 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]).
>>
>> Sadly, the prepare_prev_first didn't solve the issue. The framebuffer ->
>> MDSS takover happens, but at greetd (login) loading screen goes black and
>> never restores.
>>
>> Will need more work.
> 
> Do you see a console _while_ it boots, after the handover? I'd check the
> mode programming. Maybe, disabling panel reset would also (temporarily)
> help.

When I get access to the phone for longer period of time I'll try to debug it 
step by step. This time I had only time to flash kernel and test if it boots 
with prepare_prev_first.

David

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

-- 
David Heidelberg