[PATCH v2 0/2] drm/msm/dsi: support multiple DSC slices per packet

[PATCH v2 0/2] drm/msm/dsi: support multiple DSC slices per packet

[Alexander Koskovich]

This series adds support for sending multiple DSC slices in a single
DSI packet, which is required by some panels such as the JDI LPM026M648C.

The MSM DRM change was originally authored by Jonathan Marek [1], changed to
use an 'all slices in packet' flag which derives slice_per_pkt from slice_count
instead of manually specifying the number of slices per packet.

Was also split into two patches so they can go through different trees.

[1]: https://lore.kernel.org/all/20231114174218.19765-3-jonathan@marek.ca

Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
---
Changes in v2:
- Fix attribution to Jonathan Marek
- Link to v1: https://lore.kernel.org/r/20260318-dsi-dsc-slice-per-pkt-v1-0-1bd66b7f9e0c@pm.me

---
Alexander Koskovich (1):
      drm/mipi-dsi: add flag for sending all DSC slices in one packet

Jonathan Marek (1):
      drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

 drivers/gpu/drm/msm/dsi/dsi_host.c | 25 ++++++++++---------------
 include/drm/drm_mipi_dsi.h         |  2 ++
 2 files changed, 12 insertions(+), 15 deletions(-)
---
base-commit: f338e77383789c0cae23ca3d48adcc5e9e137e3c
change-id: 20260318-dsi-dsc-slice-per-pkt-f828429fbf0a

Best regards,
-- 
Alexander Koskovich <akoskovich@pm.me>

[PATCH v2 1/2] drm/mipi-dsi: add flag for sending all DSC slices in one packet

[Alexander Koskovich]

The MIPI DSI v1.3 spec defines two modes for transporting compressed
pixel data: one slice per packet or multiple slice widths in a single
packet (Section 8.8.24 Figure 40).

Add a MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag that panel drivers can
set to indicate that all DSC slices for a line should be packed into a
single packet. When unset should default to 1 slice per packet.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
---
 include/drm/drm_mipi_dsi.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 3aba7b380c8d..d3ad8c5d3ebe 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -138,6 +138,8 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
 #define MIPI_DSI_MODE_LPM		BIT(11)
 /* transmit data ending at the same time for all lanes within one hsync */
 #define MIPI_DSI_HS_PKT_END_ALIGNED	BIT(12)
+/* pack all DSC slices for a line into a single packet */
+#define MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT	BIT(13)
 
 enum mipi_dsi_pixel_format {
 	MIPI_DSI_FMT_RGB888,

-- 
2.53.0

[PATCH v2 2/2] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Alexander Koskovich]

From: Jonathan Marek <jonathan@marek.ca>

Some panels support multiple slice to be sent in a single DSC packet and
this feature is a must for specific panels, such as the JDI LPM026M648C.

Use the MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag to derive slice_per_pkt
from slice_count, note that most panels are expected to just work with
just one slice per packet.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index db6da99375a1..758b076ee4bf 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -166,6 +166,7 @@ struct msm_dsi_host {
 
 	struct drm_display_mode *mode;
 	struct drm_dsc_config *dsc;
+	unsigned int dsc_slice_per_pkt;
 
 	/* connected device info */
 	unsigned int channel;
@@ -927,17 +928,10 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
 	slice_per_intf = dsc->slice_count;
 
 	total_bytes_per_intf = dsc->slice_chunk_size * slice_per_intf;
-	bytes_per_pkt = dsc->slice_chunk_size; /* * slice_per_pkt; */
+	bytes_per_pkt = dsc->slice_chunk_size * msm_host->dsc_slice_per_pkt;
 
 	eol_byte_num = total_bytes_per_intf % 3;
-
-	/*
-	 * Typically, pkt_per_line = slice_per_intf * slice_per_pkt.
-	 *
-	 * Since the current driver only supports slice_per_pkt = 1,
-	 * pkt_per_line will be equal to slice per intf for now.
-	 */
-	pkt_per_line = slice_per_intf;
+	pkt_per_line = slice_per_intf / msm_host->dsc_slice_per_pkt;
 
 	if (is_cmd_mode) /* packet data type */
 		reg = DSI_COMMAND_COMPRESSION_MODE_CTRL_STREAM0_DATATYPE(MIPI_DSI_DCS_LONG_WRITE);
@@ -1088,12 +1082,8 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
 		else
 			/*
 			 * When DSC is enabled, WC = slice_chunk_size * slice_per_pkt + 1.
-			 * Currently, the driver only supports default value of slice_per_pkt = 1
-			 *
-			 * TODO: Expand mipi_dsi_device struct to hold slice_per_pkt info
-			 *       and adjust DSC math to account for slice_per_pkt.
 			 */
-			wc = msm_host->dsc->slice_chunk_size + 1;
+			wc = msm_host->dsc->slice_chunk_size * msm_host->dsc_slice_per_pkt + 1;
 
 		dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
 			DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |
@@ -1702,8 +1692,13 @@ static int dsi_host_attach(struct mipi_dsi_host *host,
 	msm_host->lanes = dsi->lanes;
 	msm_host->format = dsi->format;
 	msm_host->mode_flags = dsi->mode_flags;
-	if (dsi->dsc)
+	if (dsi->dsc) {
 		msm_host->dsc = dsi->dsc;
+		if (dsi->mode_flags & MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT)
+			msm_host->dsc_slice_per_pkt = dsi->dsc->slice_count;
+		else
+			msm_host->dsc_slice_per_pkt = 1;
+	}
 
 	ret = dsi_dev_attach(msm_host->pdev);
 	if (ret)

-- 
2.53.0

Re: [PATCH v2 2/2] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Dmitry Baryshkov]

On Wed, Mar 18, 2026 at 09:54:08AM +0000, Alexander Koskovich wrote:
> From: Jonathan Marek <jonathan@marek.ca>
> 
> Some panels support multiple slice to be sent in a single DSC packet and
> this feature is a must for specific panels, such as the JDI LPM026M648C.
> 
> Use the MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag to derive slice_per_pkt
> from slice_count, note that most panels are expected to just work with
> just one slice per packet.
> 
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 25 ++++++++++---------------
>  1 file changed, 10 insertions(+), 15 deletions(-)
> 

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


-- 
With best wishes
Dmitry

Re: [PATCH v2 1/2] drm/mipi-dsi: add flag for sending all DSC slices in one packet

[Dmitry Baryshkov]

On Wed, Mar 18, 2026 at 09:54:04AM +0000, Alexander Koskovich wrote:
> The MIPI DSI v1.3 spec defines two modes for transporting compressed
> pixel data: one slice per packet or multiple slice widths in a single
> packet (Section 8.8.24 Figure 40).
> 
> Add a MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag that panel drivers can
> set to indicate that all DSC slices for a line should be packed into a
> single packet. When unset should default to 1 slice per packet.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

As I wrote for v1, I'd prefer to get more opinions before applying

> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
> ---
>  include/drm/drm_mipi_dsi.h | 2 ++
>  1 file changed, 2 insertions(+)
> 

-- 
With best wishes
Dmitry

Re: [PATCH v2 2/2] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Konrad Dybcio]

On 3/18/26 10:54 AM, Alexander Koskovich wrote:
> From: Jonathan Marek <jonathan@marek.ca>
> 
> Some panels support multiple slice to be sent in a single DSC packet and
> this feature is a must for specific panels, such as the JDI LPM026M648C.
> 
> Use the MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag to derive slice_per_pkt
> from slice_count, note that most panels are expected to just work with
> just one slice per packet.
> 
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
> ---

Matches various formulas in the docs

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

Konrad

Re: [PATCH v2 2/2] drm/msm/dsi: support DSC configurations with slice_per_pkt > 1

[Konrad Dybcio]

On 3/19/26 11:26 AM, Konrad Dybcio wrote:
> On 3/18/26 10:54 AM, Alexander Koskovich wrote:
>> From: Jonathan Marek <jonathan@marek.ca>
>>
>> Some panels support multiple slice to be sent in a single DSC packet and
>> this feature is a must for specific panels, such as the JDI LPM026M648C.
>>
>> Use the MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag to derive slice_per_pkt
>> from slice_count, note that most panels are expected to just work with
>> just one slice per packet.
>>
>> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
>> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
>> ---
> 
> Matches various formulas in the docs
> 
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Sorry for a sloppy trailer, let me try again with the right From:..

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

Konrad

Re: [PATCH v2 1/2] drm/mipi-dsi: add flag for sending all DSC slices in one packet

[Alexander Koskovich]

On Wednesday, March 18th, 2026 at 5:58 AM, Alexander Koskovich <akoskovich@pm.me> wrote:

> The MIPI DSI v1.3 spec defines two modes for transporting compressed
> pixel data: one slice per packet or multiple slice widths in a single
> packet (Section 8.8.24 Figure 40).
> 
> Add a MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag that panel drivers can
> set to indicate that all DSC slices for a line should be packed into a
> single packet. When unset should default to 1 slice per packet.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
> ---
>  include/drm/drm_mipi_dsi.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 3aba7b380c8d..d3ad8c5d3ebe 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -138,6 +138,8 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
>  #define MIPI_DSI_MODE_LPM		BIT(11)
>  /* transmit data ending at the same time for all lanes within one hsync */
>  #define MIPI_DSI_HS_PKT_END_ALIGNED	BIT(12)
> +/* pack all DSC slices for a line into a single packet */
> +#define MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT	BIT(13)
> 
>  enum mipi_dsi_pixel_format {
>  	MIPI_DSI_FMT_RGB888,
> 
> --
> 2.53.0
> 

If there are no objections, could this be merged?

Thanks,
Alex

Re: [PATCH v2 1/2] drm/mipi-dsi: add flag for sending all DSC slices in one packet

[Konrad Dybcio]

On 4/22/26 5:15 PM, Alexander Koskovich wrote:
> On Wednesday, March 18th, 2026 at 5:58 AM, Alexander Koskovich <akoskovich@pm.me> wrote:
> 
>> The MIPI DSI v1.3 spec defines two modes for transporting compressed
>> pixel data: one slice per packet or multiple slice widths in a single
>> packet (Section 8.8.24 Figure 40).
>>
>> Add a MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT flag that panel drivers can
>> set to indicate that all DSC slices for a line should be packed into a
>> single packet. When unset should default to 1 slice per packet.
>>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
>> Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
>> ---
>>  include/drm/drm_mipi_dsi.h | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
>> index 3aba7b380c8d..d3ad8c5d3ebe 100644
>> --- a/include/drm/drm_mipi_dsi.h
>> +++ b/include/drm/drm_mipi_dsi.h
>> @@ -138,6 +138,8 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
>>  #define MIPI_DSI_MODE_LPM		BIT(11)
>>  /* transmit data ending at the same time for all lanes within one hsync */
>>  #define MIPI_DSI_HS_PKT_END_ALIGNED	BIT(12)
>> +/* pack all DSC slices for a line into a single packet */
>> +#define MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT	BIT(13)
>>
>>  enum mipi_dsi_pixel_format {
>>  	MIPI_DSI_FMT_RGB888,
>>
>> --
>> 2.53.0
>>
> 
> If there are no objections, could this be merged?

Certainly not in the merge window - patches will usually be picked up after
-rc1 drops.

Konrad

Re: [PATCH v2 0/2] drm/msm/dsi: support multiple DSC slices per packet

[Junjie Cao]

On Wed, Mar 18, 2026 at 09:53:59AM +0000, Alexander Koskovich wrote:
> This series adds support for sending multiple DSC slices in a single
> DSI packet, which is required by some panels such as the JDI LPM026M648C.

Tested on OnePlus Pad 2 (SM8650) with a Novatek NT36532 based CSOT
PPC100HB1-1 panel (dual-DSI, DSC v1.2, slice_count=2). With
MIPI_DSI_MODE_DSC_ALL_SLICES_IN_PKT set by the panel driver, the panel
comes up and renders without artifacts.

I'll be posting an NT36532 panel driver on top of this series.

Tested-by: Junjie Cao <junjie.cao@linux.dev>