[PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Mahadevan P]

On SC7280 targets, display modes with a width greater than the
max_mixer_width (2400) are rejected during mode validation when
merge3d is disabled. This limitation exists because, without a
3D merge block, two layer mixers cannot be combined(non-DSC interface),
preventing large layers from being split across mixers. As a result,
higher resolution modes cannot be supported.

Enable merge3d support on SC7280 to allow combining streams from
two layer mixers into a single non-DSC interface. This capability
removes the width restriction and enables buffer sizes beyond the
2400-pixel limit.

Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
---
Changes in v2:
  - Updated commit message for clarity (Dmitry).
---
 drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
index 8f978b9c3452..2f8688224f34 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
@@ -13,6 +13,7 @@ static const struct dpu_caps sc7280_dpu_caps = {
 	.has_dim_layer = true,
 	.has_idle_pc = true,
 	.max_linewidth = 2400,
+	.has_3d_merge = true,
 	.pixel_ram_size = DEFAULT_PIXEL_RAM_SIZE,
 };
 
@@ -134,17 +135,24 @@ static const struct dpu_pingpong_cfg sc7280_pp[] = {
 		.name = "pingpong_2", .id = PINGPONG_2,
 		.base = 0x6b000, .len = 0,
 		.sblk = &sc7280_pp_sblk,
-		.merge_3d = 0,
+		.merge_3d = MERGE_3D_1,
 		.intr_done = DPU_IRQ_IDX(MDP_SSPP_TOP0_INTR, 10),
 	}, {
 		.name = "pingpong_3", .id = PINGPONG_3,
 		.base = 0x6c000, .len = 0,
 		.sblk = &sc7280_pp_sblk,
-		.merge_3d = 0,
+		.merge_3d = MERGE_3D_1,
 		.intr_done = DPU_IRQ_IDX(MDP_SSPP_TOP0_INTR, 11),
 	},
 };
 
+static const struct dpu_merge_3d_cfg sc7280_merge_3d[] = {
+	{
+		.name = "merge_3d_1", .id = MERGE_3D_1,
+		.base = 0x4f000, .len = 0x8,
+	},
+};
+
 /* NOTE: sc7280 only has one DSC hard slice encoder */
 static const struct dpu_dsc_cfg sc7280_dsc[] = {
 	{
@@ -247,6 +255,8 @@ const struct dpu_mdss_cfg dpu_sc7280_cfg = {
 	.mixer = sc7280_lm,
 	.pingpong_count = ARRAY_SIZE(sc7280_pp),
 	.pingpong = sc7280_pp,
+	.merge_3d_count = ARRAY_SIZE(sc7280_merge_3d),
+	.merge_3d = sc7280_merge_3d,
 	.dsc_count = ARRAY_SIZE(sc7280_dsc),
 	.dsc = sc7280_dsc,
 	.wb_count = ARRAY_SIZE(sc7280_wb),

---
base-commit: efb26a23ed5f5dc3554886ab398f559dcb1de96b
change-id: 20251231-4k-969b53d2ea4c

Best regards,
-- 
Mahadevan P <mahadevan.p@oss.qualcomm.com>

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Thu, Jan 01, 2026 at 10:34:38AM +0530, Mahadevan P wrote:
> On SC7280 targets, display modes with a width greater than the
> max_mixer_width (2400) are rejected during mode validation when
> merge3d is disabled. This limitation exists because, without a
> 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> preventing large layers from being split across mixers. As a result,
> higher resolution modes cannot be supported.
> 
> Enable merge3d support on SC7280 to allow combining streams from
> two layer mixers into a single non-DSC interface. This capability
> removes the width restriction and enables buffer sizes beyond the
> 2400-pixel limit.
> 
> Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> ---
> Changes in v2:
>   - Updated commit message for clarity (Dmitry).
> ---
>  drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 

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


-- 
With best wishes
Dmitry

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Thu, 01 Jan 2026 10:34:38 +0530, Mahadevan P wrote:
> On SC7280 targets, display modes with a width greater than the
> max_mixer_width (2400) are rejected during mode validation when
> merge3d is disabled. This limitation exists because, without a
> 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> preventing large layers from being split across mixers. As a result,
> higher resolution modes cannot be supported.
> 
> [...]

Applied to msm-next, thanks!

[1/1] drm/msm/disp/dpu: add merge3d support for sc7280
      https://gitlab.freedesktop.org/lumag/msm/-/commit/2892de3f4f98

Best regards,
-- 
With best wishes
Dmitry

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Luca Weiss]

Hi Mahadevan,

On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
> On SC7280 targets, display modes with a width greater than the
> max_mixer_width (2400) are rejected during mode validation when
> merge3d is disabled. This limitation exists because, without a
> 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> preventing large layers from being split across mixers. As a result,
> higher resolution modes cannot be supported.
>
> Enable merge3d support on SC7280 to allow combining streams from
> two layer mixers into a single non-DSC interface. This capability
> removes the width restriction and enables buffer sizes beyond the
> 2400-pixel limit.
>
> Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>

This patch is causing display regression on QCM6490 fairphone-fp5.

With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
screen. When reverting this patch everything becomes working again.

See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41

@Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
quickly?

Regards
Luca

#regzbot introduced: 2892de3f4f985fa779c330468e2f341fdb762ccd

> ---
> Changes in v2:
>   - Updated commit message for clarity (Dmitry).
> ---
>  drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> index 8f978b9c3452..2f8688224f34 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/catalog/dpu_7_2_sc7280.h
> @@ -13,6 +13,7 @@ static const struct dpu_caps sc7280_dpu_caps = {
>  	.has_dim_layer = true,
>  	.has_idle_pc = true,
>  	.max_linewidth = 2400,
> +	.has_3d_merge = true,
>  	.pixel_ram_size = DEFAULT_PIXEL_RAM_SIZE,
>  };
>  
> @@ -134,17 +135,24 @@ static const struct dpu_pingpong_cfg sc7280_pp[] = {
>  		.name = "pingpong_2", .id = PINGPONG_2,
>  		.base = 0x6b000, .len = 0,
>  		.sblk = &sc7280_pp_sblk,
> -		.merge_3d = 0,
> +		.merge_3d = MERGE_3D_1,
>  		.intr_done = DPU_IRQ_IDX(MDP_SSPP_TOP0_INTR, 10),
>  	}, {
>  		.name = "pingpong_3", .id = PINGPONG_3,
>  		.base = 0x6c000, .len = 0,
>  		.sblk = &sc7280_pp_sblk,
> -		.merge_3d = 0,
> +		.merge_3d = MERGE_3D_1,
>  		.intr_done = DPU_IRQ_IDX(MDP_SSPP_TOP0_INTR, 11),
>  	},
>  };
>  
> +static const struct dpu_merge_3d_cfg sc7280_merge_3d[] = {
> +	{
> +		.name = "merge_3d_1", .id = MERGE_3D_1,
> +		.base = 0x4f000, .len = 0x8,
> +	},
> +};
> +
>  /* NOTE: sc7280 only has one DSC hard slice encoder */
>  static const struct dpu_dsc_cfg sc7280_dsc[] = {
>  	{
> @@ -247,6 +255,8 @@ const struct dpu_mdss_cfg dpu_sc7280_cfg = {
>  	.mixer = sc7280_lm,
>  	.pingpong_count = ARRAY_SIZE(sc7280_pp),
>  	.pingpong = sc7280_pp,
> +	.merge_3d_count = ARRAY_SIZE(sc7280_merge_3d),
> +	.merge_3d = sc7280_merge_3d,
>  	.dsc_count = ARRAY_SIZE(sc7280_dsc),
>  	.dsc = sc7280_dsc,
>  	.wb_count = ARRAY_SIZE(sc7280_wb),
>
> ---
> base-commit: efb26a23ed5f5dc3554886ab398f559dcb1de96b
> change-id: 20251231-4k-969b53d2ea4c
>
> Best regards,

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
> Hi Mahadevan,
> 
> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
> > On SC7280 targets, display modes with a width greater than the
> > max_mixer_width (2400) are rejected during mode validation when
> > merge3d is disabled. This limitation exists because, without a
> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> > preventing large layers from being split across mixers. As a result,
> > higher resolution modes cannot be supported.
> >
> > Enable merge3d support on SC7280 to allow combining streams from
> > two layer mixers into a single non-DSC interface. This capability
> > removes the width restriction and enables buffer sizes beyond the
> > 2400-pixel limit.
> >
> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> 
> This patch is causing display regression on QCM6490 fairphone-fp5.
> 
> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
> screen. When reverting this patch everything becomes working again.
> 
> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
> 
> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
> quickly?

Could you please provide the resource allocation parts of
debugfs/dri/0/state for both working and non-working cases?

> 
> Regards
> Luca
> 
> #regzbot introduced: 2892de3f4f985fa779c330468e2f341fdb762ccd
> 

-- 
With best wishes
Dmitry

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Luca Weiss]

Hi Dmitry,

On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
> On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
>> Hi Mahadevan,
>> 
>> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
>> > On SC7280 targets, display modes with a width greater than the
>> > max_mixer_width (2400) are rejected during mode validation when
>> > merge3d is disabled. This limitation exists because, without a
>> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
>> > preventing large layers from being split across mixers. As a result,
>> > higher resolution modes cannot be supported.
>> >
>> > Enable merge3d support on SC7280 to allow combining streams from
>> > two layer mixers into a single non-DSC interface. This capability
>> > removes the width restriction and enables buffer sizes beyond the
>> > 2400-pixel limit.
>> >
>> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
>> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
>> 
>> This patch is causing display regression on QCM6490 fairphone-fp5.
>> 
>> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
>> screen. When reverting this patch everything becomes working again.
>> 
>> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
>> 
>> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
>> quickly?
>
> Could you please provide the resource allocation parts of
> debugfs/dri/0/state for both working and non-working cases?

Working (patch reverted)

# cat /sys/kernel/debug/dri/1/state
plane[44]: plane-0
        crtc=crtc-0
        fb=71
                allocated by = phoc
                refcount=2
                format=XR24 little-endian (0x34325258)
                modifier=0x500000000000001
                size=1224x2700
                layers:
                        size[0]=1224x2700
                        pitch[0]=5120
                        offset[0]=0
                        obj[0]:
                                name=0
                                refcount=6
                                start=00103729
                                size=14680064
                                imported=no
        crtc-pos=1224x2700+0+0
        src-pos=1224.000000x2700.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=1
        sspp[0]=sspp_0
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=1224x2700+0+0
        dst[0]=1224x2700+0+0
plane[50]: plane-1
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_8
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
plane[56]: plane-2
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_9
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
plane[62]: plane-3
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_10
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
crtc[68]: crtc-0
        enable=1
        active=1
        self_refresh_active=0
        planes_changed=1
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=1
        connector_mask=1
        encoder_mask=1
        mode: "1224x2700": 90 311156 1224 1256 1264 1272 2700 2708 2710 2718 0x48 0x0
        lm[0]=2
        ctl[0]=0
crtc[69]: crtc-1
        enable=0
        active=0
        self_refresh_active=0
        planes_changed=0
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=0
        connector_mask=0
        encoder_mask=0
        mode: "": 0 0 0 0 0 0 0 0 0 0 0x0 0x0
connector[34]: DSI-1
        crtc=crtc-0
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=0
        max_requested_bpc=0
        colorspace=Default
connector[36]: DP-1
        crtc=(null)
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=1
        max_requested_bpc=0
        colorspace=Default
connector[39]: Writeback-1
        crtc=(null)
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=0
        max_requested_bpc=0
        colorspace=Default
resource mapping:
        pingpong=# # 68 # - - - - - - - - - 
        mixer=# - 68 # - - - - 
        ctl=68 # # # - - - - 
        dspp=# - - - - - - - 
        dsc=68 - - - - - - - 
        cdm=# 
        sspp=# - - - - - - - # # # - - - - - 
        cwb=- - - - 


Broken (with the patch)

# cat /sys/kernel/debug/dri/1/state
plane[44]: plane-0
        crtc=crtc-0
        fb=72
                allocated by = phoc
                refcount=2
                format=XR24 little-endian (0x34325258)
                modifier=0x500000000000001
                size=1224x2700
                layers:
                        size[0]=1224x2700
                        pitch[0]=5120
                        offset[0]=0
                        obj[0]:
                                name=0
                                refcount=6
                                start=00103729
                                size=14680064
                                imported=no
        crtc-pos=1224x2700+0+0
        src-pos=1224.000000x2700.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=1
        sspp[0]=sspp_0
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=1224x2700+0+0
        dst[0]=1224x2700+0+0
plane[50]: plane-1
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_8
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
plane[56]: plane-2
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_9
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
plane[62]: plane-3
        crtc=(null)
        fb=0
        crtc-pos=0x0+0+0
        src-pos=0.000000x0.000000+0.000000+0.000000
        rotation=1
        normalized-zpos=0
        color-encoding=ITU-R BT.601 YCbCr
        color-range=YCbCr limited range
        color_mgmt_changed=0
        color-pipeline=0
        stage=0
        sspp[0]=sspp_10
        multirect_mode[0]=none
        multirect_index[0]=solo
        src[0]=0x0+0+0
        dst[0]=0x0+0+0
crtc[68]: crtc-0
        enable=1
        active=1
        self_refresh_active=0
        planes_changed=1
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=1
        connector_mask=1
        encoder_mask=1
        mode: "1224x2700": 90 311156 1224 1256 1264 1272 2700 2708 2710 2718 0x48 0x0
        lm[0]=2
        ctl[0]=0
        lm[1]=3
        ctl[1]=0
crtc[69]: crtc-1
        enable=0
        active=0
        self_refresh_active=0
        planes_changed=0
        mode_changed=0
        active_changed=0
        connectors_changed=0
        color_mgmt_changed=0
        plane_mask=0
        connector_mask=0
        encoder_mask=0
        mode: "": 0 0 0 0 0 0 0 0 0 0 0x0 0x0
connector[34]: DSI-1
        crtc=crtc-0
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=0
        max_requested_bpc=0
        colorspace=Default
connector[36]: DP-1
        crtc=(null)
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=1
        max_requested_bpc=0
        colorspace=Default
connector[39]: Writeback-1
        crtc=(null)
        self_refresh_aware=0
        interlace_allowed=0
        ycbcr_420_allowed=0
        max_requested_bpc=0
        colorspace=Default
resource mapping:
        pingpong=# # 68 68 - - - - - - - - - 
        mixer=# - 68 68 - - - - 
        ctl=68 # # # - - - - 
        dspp=# - - - - - - - 
        dsc=68 - - - - - - - 
        cdm=# 
        sspp=# - - - - - - - # # # - - - - - 
        cwb=- - - - 

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Mon, Mar 16, 2026 at 10:08:47AM +0100, Luca Weiss wrote:
> Hi Dmitry,
> 
> On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
> > On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
> >> Hi Mahadevan,
> >> 
> >> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
> >> > On SC7280 targets, display modes with a width greater than the
> >> > max_mixer_width (2400) are rejected during mode validation when
> >> > merge3d is disabled. This limitation exists because, without a
> >> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> >> > preventing large layers from being split across mixers. As a result,
> >> > higher resolution modes cannot be supported.
> >> >
> >> > Enable merge3d support on SC7280 to allow combining streams from
> >> > two layer mixers into a single non-DSC interface. This capability
> >> > removes the width restriction and enables buffer sizes beyond the
> >> > 2400-pixel limit.
> >> >
> >> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> >> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> >> 
> >> This patch is causing display regression on QCM6490 fairphone-fp5.
> >> 
> >> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
> >> screen. When reverting this patch everything becomes working again.
> >> 
> >> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
> >> 
> >> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
> >> quickly?
> >
> > Could you please provide the resource allocation parts of
> > debugfs/dri/0/state for both working and non-working cases?
> 
> Broken (with the patch)

> resource mapping:
>         pingpong=# # 68 68 - - - - - - - - - 
>         mixer=# - 68 68 - - - - 
>         ctl=68 # # # - - - - 
>         dspp=# - - - - - - - 
>         dsc=68 - - - - - - - 
>         cdm=# 
>         sspp=# - - - - - - - # # # - - - - - 
>         cwb=- - - - 

I see. It tries to use two mixers with a single DSC. What about someting
as simple as:

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 0f4921b1a892..cbb7caa194c1 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -1410,7 +1410,8 @@ static struct msm_display_topology dpu_crtc_get_topology(
 		topology.num_lm = 2;
 	else if (topology.num_dsc == 2)
 		topology.num_lm = 2;
-	else if (dpu_kms->catalog->caps->has_3d_merge)
+	else if (dpu_kms->catalog->caps->has_3d_merge &&
+		 topology.num_dsc == 0)
 		topology.num_lm = (mode->hdisplay > MAX_HDISPLAY_SPLIT) ? 2 : 1;
 	else
 		topology.num_lm = 1;


-- 
With best wishes
Dmitry

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Luca Weiss]

On Mon Mar 16, 2026 at 8:54 PM CET, Dmitry Baryshkov wrote:
> On Mon, Mar 16, 2026 at 10:08:47AM +0100, Luca Weiss wrote:
>> Hi Dmitry,
>> 
>> On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
>> > On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
>> >> Hi Mahadevan,
>> >> 
>> >> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
>> >> > On SC7280 targets, display modes with a width greater than the
>> >> > max_mixer_width (2400) are rejected during mode validation when
>> >> > merge3d is disabled. This limitation exists because, without a
>> >> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
>> >> > preventing large layers from being split across mixers. As a result,
>> >> > higher resolution modes cannot be supported.
>> >> >
>> >> > Enable merge3d support on SC7280 to allow combining streams from
>> >> > two layer mixers into a single non-DSC interface. This capability
>> >> > removes the width restriction and enables buffer sizes beyond the
>> >> > 2400-pixel limit.
>> >> >
>> >> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
>> >> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
>> >> 
>> >> This patch is causing display regression on QCM6490 fairphone-fp5.
>> >> 
>> >> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
>> >> screen. When reverting this patch everything becomes working again.
>> >> 
>> >> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
>> >> 
>> >> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
>> >> quickly?
>> >
>> > Could you please provide the resource allocation parts of
>> > debugfs/dri/0/state for both working and non-working cases?
>> 
>> Broken (with the patch)
>
>> resource mapping:
>>         pingpong=# # 68 68 - - - - - - - - - 
>>         mixer=# - 68 68 - - - - 
>>         ctl=68 # # # - - - - 
>>         dspp=# - - - - - - - 
>>         dsc=68 - - - - - - - 
>>         cdm=# 
>>         sspp=# - - - - - - - # # # - - - - - 
>>         cwb=- - - - 
>
> I see. It tries to use two mixers with a single DSC. What about someting
> as simple as:
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index 0f4921b1a892..cbb7caa194c1 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -1410,7 +1410,8 @@ static struct msm_display_topology dpu_crtc_get_topology(
>  		topology.num_lm = 2;
>  	else if (topology.num_dsc == 2)
>  		topology.num_lm = 2;
> -	else if (dpu_kms->catalog->caps->has_3d_merge)
> +	else if (dpu_kms->catalog->caps->has_3d_merge &&
> +		 topology.num_dsc == 0)
>  		topology.num_lm = (mode->hdisplay > MAX_HDISPLAY_SPLIT) ? 2 : 1;
>  	else
>  		topology.num_lm = 1;

Thanks Dmitry, this also resolves the issue!

Tested-by: Luca Weiss <luca.weiss@fairphone.com> # qcm6490-fairphone-fp5

Regards
Luca

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Mon, Mar 16, 2026 at 10:08:47AM +0100, Luca Weiss wrote:
> Hi Dmitry,
> 
> On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
> > On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
> >> Hi Mahadevan,
> >> 
> >> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
> >> > On SC7280 targets, display modes with a width greater than the
> >> > max_mixer_width (2400) are rejected during mode validation when
> >> > merge3d is disabled. This limitation exists because, without a
> >> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> >> > preventing large layers from being split across mixers. As a result,
> >> > higher resolution modes cannot be supported.
> >> >
> >> > Enable merge3d support on SC7280 to allow combining streams from
> >> > two layer mixers into a single non-DSC interface. This capability
> >> > removes the width restriction and enables buffer sizes beyond the
> >> > 2400-pixel limit.
> >> >
> >> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> >> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> >> 
> >> This patch is causing display regression on QCM6490 fairphone-fp5.
> >> 
> >> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
> >> screen. When reverting this patch everything becomes working again.
> >> 
> >> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
> >> 
> >> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
> >> quickly?
> >
> > Could you please provide the resource allocation parts of
> > debugfs/dri/0/state for both working and non-working cases?
> 
> Working (patch reverted)
> 
> resource mapping:
>         pingpong=# # 68 # - - - - - - - - - 
>         mixer=# - 68 # - - - - 
>         ctl=68 # # # - - - - 
>         dspp=# - - - - - - - 
>         dsc=68 - - - - - - - 
>         cdm=# 
>         sspp=# - - - - - - - # # # - - - - - 
>         cwb=- - - - 
> 
> 
> Broken (with the patch)
> 
> resource mapping:
>         pingpong=# # 68 68 - - - - - - - - - 
>         mixer=# - 68 68 - - - - 
>         ctl=68 # # # - - - - 
>         dspp=# - - - - - - - 
>         dsc=68 - - - - - - - 
>         cdm=# 
>         sspp=# - - - - - - - # # # - - - - - 
>         cwb=- - - - 

As we have identified that the issue is what downstream calls
DUALPIPE_3DMERGE_DSC topology, could you please also check several
things (with the broken kernel):

- What is being returned by dpu_encoder_helper_get_3d_blend_mode() (in
  the broken config)?

- If there is any difference in working and broken configs between
  values being passed to (and programmed to the DSC) in
  dpu_encoder_prep_dsc() ?

- The same question for pclk calculation in dsi_host.c

-- 
With best wishes
Dmitry

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Luca Weiss]

On Tue Mar 17, 2026 at 6:45 PM CET, Dmitry Baryshkov wrote:
> On Mon, Mar 16, 2026 at 10:08:47AM +0100, Luca Weiss wrote:
>> Hi Dmitry,
>> 
>> On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
>> > On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
>> >> Hi Mahadevan,
>> >> 
>> >> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
>> >> > On SC7280 targets, display modes with a width greater than the
>> >> > max_mixer_width (2400) are rejected during mode validation when
>> >> > merge3d is disabled. This limitation exists because, without a
>> >> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
>> >> > preventing large layers from being split across mixers. As a result,
>> >> > higher resolution modes cannot be supported.
>> >> >
>> >> > Enable merge3d support on SC7280 to allow combining streams from
>> >> > two layer mixers into a single non-DSC interface. This capability
>> >> > removes the width restriction and enables buffer sizes beyond the
>> >> > 2400-pixel limit.
>> >> >
>> >> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
>> >> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
>> >> 
>> >> This patch is causing display regression on QCM6490 fairphone-fp5.
>> >> 
>> >> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
>> >> screen. When reverting this patch everything becomes working again.
>> >> 
>> >> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
>> >> 
>> >> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
>> >> quickly?
>> >
>> > Could you please provide the resource allocation parts of
>> > debugfs/dri/0/state for both working and non-working cases?
>> 
>> Working (patch reverted)
>> 
>> resource mapping:
>>         pingpong=# # 68 # - - - - - - - - - 
>>         mixer=# - 68 # - - - - 
>>         ctl=68 # # # - - - - 
>>         dspp=# - - - - - - - 
>>         dsc=68 - - - - - - - 
>>         cdm=# 
>>         sspp=# - - - - - - - # # # - - - - - 
>>         cwb=- - - - 
>> 
>> 
>> Broken (with the patch)
>> 
>> resource mapping:
>>         pingpong=# # 68 68 - - - - - - - - - 
>>         mixer=# - 68 68 - - - - 
>>         ctl=68 # # # - - - - 
>>         dspp=# - - - - - - - 
>>         dsc=68 - - - - - - - 
>>         cdm=# 
>>         sspp=# - - - - - - - # # # - - - - - 
>>         cwb=- - - - 
>
> As we have identified that the issue is what downstream calls
> DUALPIPE_3DMERGE_DSC topology, could you please also check several
> things (with the broken kernel):
>
> - What is being returned by dpu_encoder_helper_get_3d_blend_mode() (in
>   the broken config)?
>
> - If there is any difference in working and broken configs between
>   values being passed to (and programmed to the DSC) in
>   dpu_encoder_prep_dsc() ?
>
> - The same question for pclk calculation in dsi_host.c

Is this helpful?

Broken:
[    1.247165] dsi_calc_pclk:649 DBG pclk=111546490, bclk=83659867
[    1.490559] dpu_encoder_helper_get_3d_blend_mode:309 DBG BLEND_3D_H_ROW_INT
[    1.491008] dpu_encoder_prep_dsc:2061 DBG dsc_common_mode=0 initial_lines=1

Working:
[    0.998043] dsi_calc_pclk:649 DBG pclk=111546490, bclk=83659867
[    1.233836] dpu_encoder_helper_get_3d_blend_mode:313 DBG BLEND_3D_NONE
[    1.234277] dpu_encoder_prep_dsc:2061 DBG dsc_common_mode=0 initial_lines=1

Or do you need some more things? There's a lot of data being passed into
dpu_encoder_dsc_pipe_cfg() for example so I'm not sure which values are
relevant for this.

Regards
Luca

Re: [PATCH v2] drm/msm/disp/dpu: add merge3d support for sc7280

[Dmitry Baryshkov]

On Wed, Mar 18, 2026 at 09:45:23AM +0100, Luca Weiss wrote:
> On Tue Mar 17, 2026 at 6:45 PM CET, Dmitry Baryshkov wrote:
> > On Mon, Mar 16, 2026 at 10:08:47AM +0100, Luca Weiss wrote:
> >> Hi Dmitry,
> >> 
> >> On Fri Mar 13, 2026 at 6:14 PM CET, Dmitry Baryshkov wrote:
> >> > On Fri, Mar 13, 2026 at 09:33:18AM +0100, Luca Weiss wrote:
> >> >> Hi Mahadevan,
> >> >> 
> >> >> On Thu Jan 1, 2026 at 6:04 AM CET, Mahadevan P wrote:
> >> >> > On SC7280 targets, display modes with a width greater than the
> >> >> > max_mixer_width (2400) are rejected during mode validation when
> >> >> > merge3d is disabled. This limitation exists because, without a
> >> >> > 3D merge block, two layer mixers cannot be combined(non-DSC interface),
> >> >> > preventing large layers from being split across mixers. As a result,
> >> >> > higher resolution modes cannot be supported.
> >> >> >
> >> >> > Enable merge3d support on SC7280 to allow combining streams from
> >> >> > two layer mixers into a single non-DSC interface. This capability
> >> >> > removes the width restriction and enables buffer sizes beyond the
> >> >> > 2400-pixel limit.
> >> >> >
> >> >> > Fixes: 591e34a091d1 ("drm/msm/disp/dpu1: add support for display for SC7280 target")
> >> >> > Signed-off-by: Mahadevan P <mahadevan.p@oss.qualcomm.com>
> >> >> 
> >> >> This patch is causing display regression on QCM6490 fairphone-fp5.
> >> >> 
> >> >> With this patch in 7.0-rc3 (or 6.18.16) there's just pink noise on the
> >> >> screen. When reverting this patch everything becomes working again.
> >> >> 
> >> >> See also https://salsa.debian.org/Mobian-team/devices/kernels/qcom-linux/-/issues/41
> >> >> 
> >> >> @Dmitry: Can we revert this for later 7.0-rc, in case it's not fixed
> >> >> quickly?
> >> >
> >> > Could you please provide the resource allocation parts of
> >> > debugfs/dri/0/state for both working and non-working cases?
> >> 
> >> Working (patch reverted)
> >> 
> >> resource mapping:
> >>         pingpong=# # 68 # - - - - - - - - - 
> >>         mixer=# - 68 # - - - - 
> >>         ctl=68 # # # - - - - 
> >>         dspp=# - - - - - - - 
> >>         dsc=68 - - - - - - - 
> >>         cdm=# 
> >>         sspp=# - - - - - - - # # # - - - - - 
> >>         cwb=- - - - 
> >> 
> >> 
> >> Broken (with the patch)
> >> 
> >> resource mapping:
> >>         pingpong=# # 68 68 - - - - - - - - - 
> >>         mixer=# - 68 68 - - - - 
> >>         ctl=68 # # # - - - - 
> >>         dspp=# - - - - - - - 
> >>         dsc=68 - - - - - - - 
> >>         cdm=# 
> >>         sspp=# - - - - - - - # # # - - - - - 
> >>         cwb=- - - - 
> >
> > As we have identified that the issue is what downstream calls
> > DUALPIPE_3DMERGE_DSC topology, could you please also check several
> > things (with the broken kernel):
> >
> > - What is being returned by dpu_encoder_helper_get_3d_blend_mode() (in
> >   the broken config)?
> >
> > - If there is any difference in working and broken configs between
> >   values being passed to (and programmed to the DSC) in
> >   dpu_encoder_prep_dsc() ?
> >
> > - The same question for pclk calculation in dsi_host.c
> 
> Is this helpful?
> 
> Broken:
> [    1.247165] dsi_calc_pclk:649 DBG pclk=111546490, bclk=83659867
> [    1.490559] dpu_encoder_helper_get_3d_blend_mode:309 DBG BLEND_3D_H_ROW_INT
> [    1.491008] dpu_encoder_prep_dsc:2061 DBG dsc_common_mode=0 initial_lines=1
> 
> Working:
> [    0.998043] dsi_calc_pclk:649 DBG pclk=111546490, bclk=83659867
> [    1.233836] dpu_encoder_helper_get_3d_blend_mode:313 DBG BLEND_3D_NONE
> [    1.234277] dpu_encoder_prep_dsc:2061 DBG dsc_common_mode=0 initial_lines=1
> 
> Or do you need some more things? There's a lot of data being passed into
> dpu_encoder_dsc_pipe_cfg() for example so I'm not sure which values are
> relevant for this.

It looks sane up. I will try asking internally. But for now the posted
patch should be good to go.

-- 
With best wishes
Dmitry