[PATCH v3 0/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[PATCH v3 0/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Sudarshan Shetty]

Hi all,
 
This patch refines dual-link LVDS support in the SN65DSI83/84
DSI-to-LVDS bridge driver.
 
Recent upstream changes added support for dual-link LVDS timing
adjustments and related fixes:
 - Halving horizontal timing parameters
 - Test pattern handling adjustments
 - DSI clock range correction
 
However, during validation on our platform, LVDS output remained
unstable for certain panels due to the DSI mode configuration.
 
Specifically, the following flags were found to cause issues:
 
 - MIPI_DSI_MODE_VIDEO_NO_HFP
 - MIPI_DSI_MODE_VIDEO_NO_HBP
 
These disable transmission of horizontal front porch (HFP) and
back porch (HBP) timings over the DSI link. The SN65DSI bridge
relies on complete horizontal timing information to reconstruct
LVDS timings, and omitting these parameters results in incorrect
or unstable output.
 
Additionally:
 
 - MIPI_DSI_MODE_VIDEO_BURST
 
While supported by the hardware, burst mode operation depends on
continuous clocking from the DSI host. In practice, this may lead
to instability depending on the host controller implementation,
as the link may transition to LP mode between bursts.
 
Removing these flags ensures that:
 - Full timing information is transmitted
 - The bridge can correctly reconstruct LVDS timings
 - Output remains stable across tested panels
 
This patch updates the DSI mode configuration accordingly.
 
This patch is based on recent SN65DSI83 dual-link LVDS fixes:
 - https://lore.kernel.org/lkml/20260309-ti-sn65dsi83-dual-lvds-fixes-and-test-pattern-v2-1-e6aaa7e1d181@bootlin.com/ 

Changes in v3:
 - Rebased on top of latest upstream changes
 - Dropped previously proposed dual-link DT property and related handling
   as equivalent functionality is now available upstream
 - Refined DSI mode flag configuration to ensure stable LVDS output
 - Added detailed justification for removing NO_HFP/NO_HBP and BURST mode
 
Changes in v2:
 - Introduced ti,dual-link-video-mode DT property
 - Added DT binding documentation for the new property
 - Update driver to read the DT property and apply dual-link
   configuration conditionally
 - Adjust DSI mode flags when dual-link video mode is enabled
 - Update commit messages 

Thanks,
Anusha

Sudarshan Shetty (1):
  drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

-- 
2.34.1

[PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Sudarshan Shetty]

The current DSI mode configuration enables VIDEO_BURST and disables
horizontal front porch (HFP) and back porch (HBP) transmission using
MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.

However, the SN65DSI83/84 bridge relies on receiving full horizontal
timing information over DSI in order to correctly reconstruct the LVDS
output timings. When HFP and HBP are not transmitted, the bridge cannot
recreate the required timing parameters, resulting in unstable or
missing display output on some panels.

Additionally, while burst mode is supported by the hardware, its use
depends on continuous clock behavior from the DSI host. In practice,
burst mode may introduce instability depending on the host controller
implementation, as the DSI link may transition to low-power state
between bursts.

In testing, removing burst mode and ensuring full horizontal timing
transmission results in stable LVDS output across affected panels.

Update the DSI mode flags to:
  - Drop MIPI_DSI_MODE_VIDEO_BURST
  - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
  - Drop MIPI_DSI_MODE_VIDEO_NO_HBP

This aligns with common system configurations where non-burst mode is
preferred and full timing information is transmitted over DSI.

Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index fef6bca3273f..9d51dc2b75bc 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -976,9 +976,8 @@ static int sn65dsi83_host_attach(struct sn65dsi83 *ctx)
 
 	dsi->lanes = dsi_lanes;
 	dsi->format = MIPI_DSI_FMT_RGB888;
-	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
-			  MIPI_DSI_MODE_VIDEO_NO_HFP | MIPI_DSI_MODE_VIDEO_NO_HBP |
-			  MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
+	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA |
+			  MIPI_DSI_MODE_NO_EOT_PACKET;
 
 	ret = devm_mipi_dsi_attach(dev, dsi);
 	if (ret < 0) {
-- 
2.34.1

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

Hello Sudarshan,

On Sun Apr 12, 2026 at 7:38 AM CEST, Sudarshan Shetty wrote:
> The current DSI mode configuration enables VIDEO_BURST and disables
> horizontal front porch (HFP) and back porch (HBP) transmission using
> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
>
> However, the SN65DSI83/84 bridge relies on receiving full horizontal
> timing information over DSI in order to correctly reconstruct the LVDS
> output timings. When HFP and HBP are not transmitted, the bridge cannot
> recreate the required timing parameters, resulting in unstable or
> missing display output on some panels.
>
> Additionally, while burst mode is supported by the hardware, its use
> depends on continuous clock behavior from the DSI host. In practice,
> burst mode may introduce instability depending on the host controller
> implementation, as the DSI link may transition to low-power state
> between bursts.
>
> In testing, removing burst mode and ensuring full horizontal timing
> transmission results in stable LVDS output across affected panels.
>
> Update the DSI mode flags to:
>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
>
> This aligns with common system configurations where non-burst mode is
> preferred and full timing information is transmitted over DSI.
>
> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>

Thanks for having gone into the details and provide a good explanation for
the removal of these three flags.

It would be still great to have authoritative info from TI, possibly as an
update to the documentation.

I managed to test on a board with i.MX93, a TI SN65DSI84 and a 1920x1080p60
panel, and:

 - no image shown with the current mainline driver
 - it works by removing only MIPI_DSI_MODE_VIDEO_BURST (my current setup)
 - it works with this patch applied

Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx93 1920x1080p60

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

On Wed Apr 15, 2026 at 9:13 AM CEST, Luca Ceresoli wrote:
> Hello Sudarshan,
>
> On Sun Apr 12, 2026 at 7:38 AM CEST, Sudarshan Shetty wrote:
>> The current DSI mode configuration enables VIDEO_BURST and disables
>> horizontal front porch (HFP) and back porch (HBP) transmission using
>> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
>>
>> However, the SN65DSI83/84 bridge relies on receiving full horizontal
>> timing information over DSI in order to correctly reconstruct the LVDS
>> output timings. When HFP and HBP are not transmitted, the bridge cannot
>> recreate the required timing parameters, resulting in unstable or
>> missing display output on some panels.
>>
>> Additionally, while burst mode is supported by the hardware, its use
>> depends on continuous clock behavior from the DSI host. In practice,
>> burst mode may introduce instability depending on the host controller
>> implementation, as the DSI link may transition to low-power state
>> between bursts.
>>
>> In testing, removing burst mode and ensuring full horizontal timing
>> transmission results in stable LVDS output across affected panels.
>>
>> Update the DSI mode flags to:
>>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
>>
>> This aligns with common system configurations where non-burst mode is
>> preferred and full timing information is transmitted over DSI.
>>
>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>
> Thanks for having gone into the details and provide a good explanation for
> the removal of these three flags.
>
> It would be still great to have authoritative info from TI, possibly as an
> update to the documentation.
>
> I managed to test on a board with i.MX93, a TI SN65DSI84 and a 1920x1080p60
> panel, and:
>
>  - no image shown with the current mainline driver
>  - it works by removing only MIPI_DSI_MODE_VIDEO_BURST (my current setup)
>  - it works with this patch applied
>
> Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx93 1920x1080p60

And tested on a i.MX8MP board too, with a different 1920x1080p60
panel. This one was working without the patch and is equally working with
the patch applied.

Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx8mp 1920x1080p60

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Alexander Stein]

Am Sonntag, 12. April 2026, 07:38:11 CEST schrieb Sudarshan Shetty:
> The current DSI mode configuration enables VIDEO_BURST and disables
> horizontal front porch (HFP) and back porch (HBP) transmission using
> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
> 
> However, the SN65DSI83/84 bridge relies on receiving full horizontal
> timing information over DSI in order to correctly reconstruct the LVDS
> output timings. When HFP and HBP are not transmitted, the bridge cannot
> recreate the required timing parameters, resulting in unstable or
> missing display output on some panels.
> 
> Additionally, while burst mode is supported by the hardware, its use
> depends on continuous clock behavior from the DSI host. In practice,
> burst mode may introduce instability depending on the host controller
> implementation, as the DSI link may transition to low-power state
> between bursts.
> 
> In testing, removing burst mode and ensuring full horizontal timing
> transmission results in stable LVDS output across affected panels.
> 
> Update the DSI mode flags to:
>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
> 
> This aligns with common system configurations where non-burst mode is
> preferred and full timing information is transmitted over DSI.
> 
> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>

Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com># imx8mq, imx8mm, imx8mm

on both tm070jvhg33 and g133han01 displays.

Best regards
Alexander

> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index fef6bca3273f..9d51dc2b75bc 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -976,9 +976,8 @@ static int sn65dsi83_host_attach(struct sn65dsi83 *ctx)
>  
>  	dsi->lanes = dsi_lanes;
>  	dsi->format = MIPI_DSI_FMT_RGB888;
> -	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> -			  MIPI_DSI_MODE_VIDEO_NO_HFP | MIPI_DSI_MODE_VIDEO_NO_HBP |
> -			  MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA |
> +			  MIPI_DSI_MODE_NO_EOT_PACKET;
>  
>  	ret = devm_mipi_dsi_attach(dev, dsi);
>  	if (ret < 0) {
> 


-- 
TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany
Amtsgericht München, HRB 105018
Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider
http://www.tq-group.com/

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 15-04-2026 12:43, Luca Ceresoli wrote:
> Hello Sudarshan,
> 
> On Sun Apr 12, 2026 at 7:38 AM CEST, Sudarshan Shetty wrote:
>> The current DSI mode configuration enables VIDEO_BURST and disables
>> horizontal front porch (HFP) and back porch (HBP) transmission using
>> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
>>
>> However, the SN65DSI83/84 bridge relies on receiving full horizontal
>> timing information over DSI in order to correctly reconstruct the LVDS
>> output timings. When HFP and HBP are not transmitted, the bridge cannot
>> recreate the required timing parameters, resulting in unstable or
>> missing display output on some panels.
>>
>> Additionally, while burst mode is supported by the hardware, its use
>> depends on continuous clock behavior from the DSI host. In practice,
>> burst mode may introduce instability depending on the host controller
>> implementation, as the DSI link may transition to low-power state
>> between bursts.
>>
>> In testing, removing burst mode and ensuring full horizontal timing
>> transmission results in stable LVDS output across affected panels.
>>
>> Update the DSI mode flags to:
>>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
>>
>> This aligns with common system configurations where non-burst mode is
>> preferred and full timing information is transmitted over DSI.
>>
>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
> 
> Thanks for having gone into the details and provide a good explanation for
> the removal of these three flags.
> 
> It would be still great to have authoritative info from TI, possibly as an
> update to the documentation.
> 
> I managed to test on a board with i.MX93, a TI SN65DSI84 and a 1920x1080p60
> panel, and:
> 
>  - no image shown with the current mainline driver
>  - it works by removing only MIPI_DSI_MODE_VIDEO_BURST (my current setup)
>  - it works with this patch applied
> 
> Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx93 1920x1080p60
> 

Thanks for testing the patch and for the Tested-by tag. 
I’ll reach out to TI for clarification on the DSI mode flag behavior and
any documentation updates, and will share any feedback I receive, though I
cannot guarantee a response.
> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 16-04-2026 14:40, tessolveupstream@gmail.com wrote:
> 
> 
> On 15-04-2026 12:43, Luca Ceresoli wrote:
>> Hello Sudarshan,
>>
>> On Sun Apr 12, 2026 at 7:38 AM CEST, Sudarshan Shetty wrote:
>>> The current DSI mode configuration enables VIDEO_BURST and disables
>>> horizontal front porch (HFP) and back porch (HBP) transmission using
>>> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
>>>
>>> However, the SN65DSI83/84 bridge relies on receiving full horizontal
>>> timing information over DSI in order to correctly reconstruct the LVDS
>>> output timings. When HFP and HBP are not transmitted, the bridge cannot
>>> recreate the required timing parameters, resulting in unstable or
>>> missing display output on some panels.
>>>
>>> Additionally, while burst mode is supported by the hardware, its use
>>> depends on continuous clock behavior from the DSI host. In practice,
>>> burst mode may introduce instability depending on the host controller
>>> implementation, as the DSI link may transition to low-power state
>>> between bursts.
>>>
>>> In testing, removing burst mode and ensuring full horizontal timing
>>> transmission results in stable LVDS output across affected panels.
>>>
>>> Update the DSI mode flags to:
>>>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
>>>
>>> This aligns with common system configurations where non-burst mode is
>>> preferred and full timing information is transmitted over DSI.
>>>
>>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>>
>> Thanks for having gone into the details and provide a good explanation for
>> the removal of these three flags.
>>
>> It would be still great to have authoritative info from TI, possibly as an
>> update to the documentation.
>>
>> I managed to test on a board with i.MX93, a TI SN65DSI84 and a 1920x1080p60
>> panel, and:
>>
>>  - no image shown with the current mainline driver
>>  - it works by removing only MIPI_DSI_MODE_VIDEO_BURST (my current setup)
>>  - it works with this patch applied
>>
>> Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx93 1920x1080p60
>>
> 
> Thanks for testing the patch and for the Tested-by tag. 
> I’ll reach out to TI for clarification on the DSI mode flag behavior and
> any documentation updates, and will share any feedback I receive, though I
> cannot guarantee a response.

I had reached out to TI for clarification and any related documentation 
updates, but I have not received any response so far.Given this, it is 
uncertain whether we will be able to obtain further details or official 
confirmation from TI in the near term.

I would appreciate your guidance on how you would prefer us to proceed 
from here.
>> Luca
>>
>> --
>> Luca Ceresoli, Bootlin
>> Embedded Linux and Kernel engineering
>> https://bootlin.com
> 

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 21-04-2026 11:31, tessolveupstream@gmail.com wrote:
> 
> 
> On 16-04-2026 14:40, tessolveupstream@gmail.com wrote:
>>
>>
>> On 15-04-2026 12:43, Luca Ceresoli wrote:
>>> Hello Sudarshan,
>>>
>>> On Sun Apr 12, 2026 at 7:38 AM CEST, Sudarshan Shetty wrote:
>>>> The current DSI mode configuration enables VIDEO_BURST and disables
>>>> horizontal front porch (HFP) and back porch (HBP) transmission using
>>>> MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP.
>>>>
>>>> However, the SN65DSI83/84 bridge relies on receiving full horizontal
>>>> timing information over DSI in order to correctly reconstruct the LVDS
>>>> output timings. When HFP and HBP are not transmitted, the bridge cannot
>>>> recreate the required timing parameters, resulting in unstable or
>>>> missing display output on some panels.
>>>>
>>>> Additionally, while burst mode is supported by the hardware, its use
>>>> depends on continuous clock behavior from the DSI host. In practice,
>>>> burst mode may introduce instability depending on the host controller
>>>> implementation, as the DSI link may transition to low-power state
>>>> between bursts.
>>>>
>>>> In testing, removing burst mode and ensuring full horizontal timing
>>>> transmission results in stable LVDS output across affected panels.
>>>>
>>>> Update the DSI mode flags to:
>>>>   - Drop MIPI_DSI_MODE_VIDEO_BURST
>>>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HFP
>>>>   - Drop MIPI_DSI_MODE_VIDEO_NO_HBP
>>>>
>>>> This aligns with common system configurations where non-burst mode is
>>>> preferred and full timing information is transmitted over DSI.
>>>>
>>>> Signed-off-by: Sudarshan Shetty <tessolveupstream@gmail.com>
>>>
>>> Thanks for having gone into the details and provide a good explanation for
>>> the removal of these three flags.
>>>
>>> It would be still great to have authoritative info from TI, possibly as an
>>> update to the documentation.
>>>
>>> I managed to test on a board with i.MX93, a TI SN65DSI84 and a 1920x1080p60
>>> panel, and:
>>>
>>>  - no image shown with the current mainline driver
>>>  - it works by removing only MIPI_DSI_MODE_VIDEO_BURST (my current setup)
>>>  - it works with this patch applied
>>>
>>> Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # imx93 1920x1080p60
>>>
>>
>> Thanks for testing the patch and for the Tested-by tag. 
>> I’ll reach out to TI for clarification on the DSI mode flag behavior and
>> any documentation updates, and will share any feedback I receive, though I
>> cannot guarantee a response.
> 
> I had reached out to TI for clarification and any related documentation 
> updates, but I have not received any response so far.Given this, it is 
> uncertain whether we will be able to obtain further details or official 
> confirmation from TI in the near term.
> 
> I would appreciate your guidance on how you would prefer us to proceed 
> from here.

I followed up with TI, and they pointed us to the relevant sections in the 
SN65DSI83/84/86 datasheets covering DSI video transmission specifications.

https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84

As per datasheet Section 7.4.7, the device operates in DSI video mode with 
fixed horizontal timing, where HBP, and HFP are explicitly defined and expected 
to be present as part of the video line structure. The timing description in 
this section assumes standard non‑burst video transmission with all horizontal 
blanking intervals accounted for.
 
The datasheet does not document support for DSI video burst mode, nor does it 
mention support for omitting horizontal front or back porch intervals. In 
particular, there is no indication that the device can operate with collapsed 
or suppressed horizontal blanking, as enabled by MIPI_DSI_MODE_VIDEO_BURST, 
MIPI_DSI_MODE_VIDEO_NO_HFP, or MIPI_DSI_MODE_VIDEO_NO_HBP.

Enabling these modes results in a mismatch between the host‑generated DSI timing 
and the device’s expected fixed timing model described in the datasheet, which 
leads to incorrect display behavior. This is consistent with our observations: 
the display fails when these modes are enabled, and operates correctly when using 
standard non‑burst video mode with explicit HBP/HFP timing.
 
Therefore, removing these flags aligns the driver configuration with the 
datasheet‑defined timing requirements rather than acting as a workaround.
 
They also shared the following E2E FAQ for reference:
https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1382976/faq-sn65dsi8x-programming-tools?tisearch=e2e-sitesearch&keymatch=sn65dsi86

However, they did not provide any additional clarification beyond what is already 
documented and indicated that there are currently no plans to further support or 
update the Linux driver.
 
Given this, it seems unlikely that we will receive more detailed or authoritative 
guidance from TI on the specific mode flag usage.
 
Please let me know how you would prefer us to proceed from here.
>>> Luca
>>>
>>> --
>>> Luca Ceresoli, Bootlin
>>> Embedded Linux and Kernel engineering
>>> https://bootlin.com
>>
> 

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

Hello,

On Thu Apr 23, 2026 at 11:16 AM CEST, tessolveupstream wrote:

>> I had reached out to TI for clarification and any related documentation
>> updates, but I have not received any response so far.Given this, it is
>> uncertain whether we will be able to obtain further details or official
>> confirmation from TI in the near term.
>>
>> I would appreciate your guidance on how you would prefer us to proceed
>> from here.
>
> I followed up with TI, and they pointed us to the relevant sections in the
> SN65DSI83/84/86 datasheets covering DSI video transmission specifications.

Thanks for keeping on! I'm also trying to get info from TI, I'm keeping you
up to date if that will happen.

>> https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84
>
> As per datasheet Section 7.4.7, the device operates in DSI video mode with
> fixed horizontal timing, where HBP, and HFP are explicitly defined and expected
> to be present as part of the video line structure. The timing description in
> this section assumes standard non‑burst video transmission with all horizontal
> blanking intervals accounted for.
>
> The datasheet does not document support for DSI video burst mode,

This sentence seems incorrect. Section 7.4.7 starts with this sentence:
"The SN65DSI84 supports burst video mode and non-burst video mode ...".

Even though asa matter of fact it looks like many users have issues that
get solved by disabling burst mode.

> nor does it
> mention support for omitting horizontal front or back porch intervals. In
> particular, there is no indication that the device can operate with collapsed
> or suppressed horizontal blanking, as enabled by MIPI_DSI_MODE_VIDEO_BURST,
> MIPI_DSI_MODE_VIDEO_NO_HFP, or MIPI_DSI_MODE_VIDEO_NO_HBP.

This is correct.

We can still try to get TI feedback, but it that won't happen in, say, a
few weeks then I think we should apply this patch.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 24-04-2026 13:55, Luca Ceresoli wrote:
> Hello,
> 
> On Thu Apr 23, 2026 at 11:16 AM CEST, tessolveupstream wrote:
> 
>>> I had reached out to TI for clarification and any related documentation
>>> updates, but I have not received any response so far.Given this, it is
>>> uncertain whether we will be able to obtain further details or official
>>> confirmation from TI in the near term.
>>>
>>> I would appreciate your guidance on how you would prefer us to proceed
>>> from here.
>>
>> I followed up with TI, and they pointed us to the relevant sections in the
>> SN65DSI83/84/86 datasheets covering DSI video transmission specifications.
> 
> Thanks for keeping on! I'm also trying to get info from TI, I'm keeping you
> up to date if that will happen.
> 
>>> https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84
>>
>> As per datasheet Section 7.4.7, the device operates in DSI video mode with
>> fixed horizontal timing, where HBP, and HFP are explicitly defined and expected
>> to be present as part of the video line structure. The timing description in
>> this section assumes standard non‑burst video transmission with all horizontal
>> blanking intervals accounted for.
>>
>> The datasheet does not document support for DSI video burst mode,
> 
> This sentence seems incorrect. Section 7.4.7 starts with this sentence:
> "The SN65DSI84 supports burst video mode and non-burst video mode ...".
> 
> Even though asa matter of fact it looks like many users have issues that
> get solved by disabling burst mode.
> 
>> nor does it
>> mention support for omitting horizontal front or back porch intervals. In
>> particular, there is no indication that the device can operate with collapsed
>> or suppressed horizontal blanking, as enabled by MIPI_DSI_MODE_VIDEO_BURST,
>> MIPI_DSI_MODE_VIDEO_NO_HFP, or MIPI_DSI_MODE_VIDEO_NO_HBP.
> 
> This is correct.
> 
> We can still try to get TI feedback, but it that won't happen in, say, a
> few weeks then I think we should apply this patch.
>

We have not received any further updates from TI regarding this issue, and 
at this point, we are not sure if we will get additional feedback from them.
As you had mentioned earlier that the patch could be considered after 
waiting for some time, could you please let us know how we can proceed 
further from here?
 
> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

Hello,

On Tue May 19, 2026 at 10:48 AM CEST, tessolveupstream wrote:
>
>
> On 24-04-2026 13:55, Luca Ceresoli wrote:
>> Hello,
>>
>> On Thu Apr 23, 2026 at 11:16 AM CEST, tessolveupstream wrote:
>>
>>>> I had reached out to TI for clarification and any related documentation
>>>> updates, but I have not received any response so far.Given this, it is
>>>> uncertain whether we will be able to obtain further details or official
>>>> confirmation from TI in the near term.
>>>>
>>>> I would appreciate your guidance on how you would prefer us to proceed
>>>> from here.
>>>
>>> I followed up with TI, and they pointed us to the relevant sections in the
>>> SN65DSI83/84/86 datasheets covering DSI video transmission specifications.
>>
>> Thanks for keeping on! I'm also trying to get info from TI, I'm keeping you
>> up to date if that will happen.
>>
>>>> https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84
>>>
>>> As per datasheet Section 7.4.7, the device operates in DSI video mode with
>>> fixed horizontal timing, where HBP, and HFP are explicitly defined and expected
>>> to be present as part of the video line structure. The timing description in
>>> this section assumes standard non‑burst video transmission with all horizontal
>>> blanking intervals accounted for.
>>>
>>> The datasheet does not document support for DSI video burst mode,
>>
>> This sentence seems incorrect. Section 7.4.7 starts with this sentence:
>> "The SN65DSI84 supports burst video mode and non-burst video mode ...".
>>
>> Even though asa matter of fact it looks like many users have issues that
>> get solved by disabling burst mode.
>>
>>> nor does it
>>> mention support for omitting horizontal front or back porch intervals. In
>>> particular, there is no indication that the device can operate with collapsed
>>> or suppressed horizontal blanking, as enabled by MIPI_DSI_MODE_VIDEO_BURST,
>>> MIPI_DSI_MODE_VIDEO_NO_HFP, or MIPI_DSI_MODE_VIDEO_NO_HBP.
>>
>> This is correct.
>>
>> We can still try to get TI feedback, but it that won't happen in, say, a
>> few weeks then I think we should apply this patch.
>>
>
> We have not received any further updates from TI regarding this issue, and
> at this point, we are not sure if we will get additional feedback from them.
> As you had mentioned earlier that the patch could be considered after
> waiting for some time, could you please let us know how we can proceed
> further from here?

I am getting some feedback from TI, but it is taking some time.

For the time being I think it is clear that HBP and HFP are required, and
so removing the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
in your patch seems to be fully correct, even though this had no effect on
the panel I tested.

I'm still trying to get some better info to ensure that switching from
burst mode to non-burst mode is not expected to have side effects.

For thi reason, I think it would be great if you could send a new version
with two separate patches: the first one enabling HFP and HBP and which can
be applied right away, the second to disable burst mode for which I'd wait
a bit longer for TI feedback. You can keep the Tested-by lines.

I understand this is painful and taking time, but it's important to ensure
as much as possible that the change won't introduce regressions on existing
hardware.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 19-05-2026 17:13, Luca Ceresoli wrote:
> Hello,
> 
> On Tue May 19, 2026 at 10:48 AM CEST, tessolveupstream wrote:
>>
>>
>> On 24-04-2026 13:55, Luca Ceresoli wrote:
>>> Hello,
>>>
>>> On Thu Apr 23, 2026 at 11:16 AM CEST, tessolveupstream wrote:
>>>
>>>>> I had reached out to TI for clarification and any related documentation
>>>>> updates, but I have not received any response so far.Given this, it is
>>>>> uncertain whether we will be able to obtain further details or official
>>>>> confirmation from TI in the near term.
>>>>>
>>>>> I would appreciate your guidance on how you would prefer us to proceed
>>>>> from here.
>>>>
>>>> I followed up with TI, and they pointed us to the relevant sections in the
>>>> SN65DSI83/84/86 datasheets covering DSI video transmission specifications.
>>>
>>> Thanks for keeping on! I'm also trying to get info from TI, I'm keeping you
>>> up to date if that will happen.
>>>
>>>>> https://www.ti.com/lit/ds/symlink/sn65dsi84.pdf?ts=1776924088430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN65DSI84
>>>>
>>>> As per datasheet Section 7.4.7, the device operates in DSI video mode with
>>>> fixed horizontal timing, where HBP, and HFP are explicitly defined and expected
>>>> to be present as part of the video line structure. The timing description in
>>>> this section assumes standard non‑burst video transmission with all horizontal
>>>> blanking intervals accounted for.
>>>>
>>>> The datasheet does not document support for DSI video burst mode,
>>>
>>> This sentence seems incorrect. Section 7.4.7 starts with this sentence:
>>> "The SN65DSI84 supports burst video mode and non-burst video mode ...".
>>>
>>> Even though asa matter of fact it looks like many users have issues that
>>> get solved by disabling burst mode.
>>>
>>>> nor does it
>>>> mention support for omitting horizontal front or back porch intervals. In
>>>> particular, there is no indication that the device can operate with collapsed
>>>> or suppressed horizontal blanking, as enabled by MIPI_DSI_MODE_VIDEO_BURST,
>>>> MIPI_DSI_MODE_VIDEO_NO_HFP, or MIPI_DSI_MODE_VIDEO_NO_HBP.
>>>
>>> This is correct.
>>>
>>> We can still try to get TI feedback, but it that won't happen in, say, a
>>> few weeks then I think we should apply this patch.
>>>
>>
>> We have not received any further updates from TI regarding this issue, and
>> at this point, we are not sure if we will get additional feedback from them.
>> As you had mentioned earlier that the patch could be considered after
>> waiting for some time, could you please let us know how we can proceed
>> further from here?
> 
> I am getting some feedback from TI, but it is taking some time.
> 
> For the time being I think it is clear that HBP and HFP are required, and
> so removing the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
> in your patch seems to be fully correct, even though this had no effect on
> the panel I tested.
> 
> I'm still trying to get some better info to ensure that switching from
> burst mode to non-burst mode is not expected to have side effects.
> 
> For thi reason, I think it would be great if you could send a new version
> with two separate patches: the first one enabling HFP and HBP and which can
> be applied right away, the second to disable burst mode for which I'd wait
> a bit longer for TI feedback. You can keep the Tested-by lines.
> 

Thanks for the clarification. I just wanted to confirm my understanding 
regarding the patch split you suggested.

From your comments, my understanding is that the first patch would only 
enable HFP and HBP by removing MIPI_DSI_MODE_VIDEO_NO_HFP and 
MIPI_DSI_MODE_VIDEO_NO_HBP, while keeping burst mode enabled, so the mode 
flags would become:

dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | 
          MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;

Then, the second patch would only disable burst mode, resulting in:

dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA | 
          MIPI_DSI_MODE_NO_EOT_PACKET;

Could you please confirm whether my understanding is correct?

Also, from our testing, when using:

dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | 
          MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;

we are not able to get display output. I just wanted to mention this 
observation in case it is relevant to the patch split discussion.

Additionally, regarding the Tested-by tags you mentioned earlier, 
should I carry them forward to both patches, or would you prefer them 
only on the applicable patch?


> I understand this is painful and taking time, but it's important to ensure
> as much as possible that the change won't introduce regressions on existing
> hardware.
> 
> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

Hello,

On Wed May 20, 2026 at 11:04 AM CEST, tessolveupstream wrote:

[...]

>>> We have not received any further updates from TI regarding this issue, and
>>> at this point, we are not sure if we will get additional feedback from them.
>>> As you had mentioned earlier that the patch could be considered after
>>> waiting for some time, could you please let us know how we can proceed
>>> further from here?
>>
>> I am getting some feedback from TI, but it is taking some time.
>>
>> For the time being I think it is clear that HBP and HFP are required, and
>> so removing the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
>> in your patch seems to be fully correct, even though this had no effect on
>> the panel I tested.
>>
>> I'm still trying to get some better info to ensure that switching from
>> burst mode to non-burst mode is not expected to have side effects.
>>
>> For thi reason, I think it would be great if you could send a new version
>> with two separate patches: the first one enabling HFP and HBP and which can
>> be applied right away, the second to disable burst mode for which I'd wait
>> a bit longer for TI feedback. You can keep the Tested-by lines.
>>
>
> Thanks for the clarification. I just wanted to confirm my understanding
> regarding the patch split you suggested.
>
> From your comments, my understanding is that the first patch would only
> enable HFP and HBP by removing MIPI_DSI_MODE_VIDEO_NO_HFP and
> MIPI_DSI_MODE_VIDEO_NO_HBP, while keeping burst mode enabled, so the mode
> flags would become:
>
> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>           MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
>
> Then, the second patch would only disable burst mode, resulting in:
>
> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA |
>           MIPI_DSI_MODE_NO_EOT_PACKET;
>
> Could you please confirm whether my understanding is correct?

Yes, correct.

> Also, from our testing, when using:
>
> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>           MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
>
> we are not able to get display output.

This is the case for the panel I worked on as well. In the practice we both
observe that non-burst mode is what fixes the panel, but there is no clear
explanation of the reason in the docs (that's what I hope to discover from
TI).

On the other hand the HBP and HFP are clearly required by the docs, so it
should be fine to enable those without waiting for further info from
TI. This is not fixing your and my panel, but it's a fix, no doubt.

> I just wanted to mention this
> observation in case it is relevant to the patch split discussion.
>
> Additionally, regarding the Tested-by tags you mentioned earlier,
> should I carry them forward to both patches, or would you prefer them
> only on the applicable patch?

I'd say yes. People who sent these tags have tested a patch that is the sum
of the two future patches, so I'd say it's OK to keep the R-by on both
patches.

Thanks for your patience. We'll get to the bottom of this issue! :)

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 20-05-2026 17:08, Luca Ceresoli wrote:
> Hello,
> 
> On Wed May 20, 2026 at 11:04 AM CEST, tessolveupstream wrote:
> 
> [...]
> 
>>>> We have not received any further updates from TI regarding this issue, and
>>>> at this point, we are not sure if we will get additional feedback from them.
>>>> As you had mentioned earlier that the patch could be considered after
>>>> waiting for some time, could you please let us know how we can proceed
>>>> further from here?
>>>
>>> I am getting some feedback from TI, but it is taking some time.
>>>
>>> For the time being I think it is clear that HBP and HFP are required, and
>>> so removing the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP
>>> in your patch seems to be fully correct, even though this had no effect on
>>> the panel I tested.
>>>
>>> I'm still trying to get some better info to ensure that switching from
>>> burst mode to non-burst mode is not expected to have side effects.
>>>
>>> For thi reason, I think it would be great if you could send a new version
>>> with two separate patches: the first one enabling HFP and HBP and which can
>>> be applied right away, the second to disable burst mode for which I'd wait
>>> a bit longer for TI feedback. You can keep the Tested-by lines.
>>>
>>
>> Thanks for the clarification. I just wanted to confirm my understanding
>> regarding the patch split you suggested.
>>
>> From your comments, my understanding is that the first patch would only
>> enable HFP and HBP by removing MIPI_DSI_MODE_VIDEO_NO_HFP and
>> MIPI_DSI_MODE_VIDEO_NO_HBP, while keeping burst mode enabled, so the mode
>> flags would become:
>>
>> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>>           MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
>>
>> Then, the second patch would only disable burst mode, resulting in:
>>
>> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA |
>>           MIPI_DSI_MODE_NO_EOT_PACKET;
>>
>> Could you please confirm whether my understanding is correct?
> 
> Yes, correct.
>

Thank you for the clarification. 
>> Also, from our testing, when using:
>>
>> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
>>           MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET;
>>
>> we are not able to get display output.
> 
> This is the case for the panel I worked on as well. In the practice we both
> observe that non-burst mode is what fixes the panel, but there is no clear
> explanation of the reason in the docs (that's what I hope to discover from
> TI).
> 
> On the other hand the HBP and HFP are clearly required by the docs, so it
> should be fine to enable those without waiting for further info from
> TI. This is not fixing your and my panel, but it's a fix, no doubt.
> 
>> I just wanted to mention this
>> observation in case it is relevant to the patch split discussion.
>>
>> Additionally, regarding the Tested-by tags you mentioned earlier,
>> should I carry them forward to both patches, or would you prefer them
>> only on the applicable patch?
> 
> I'd say yes. People who sent these tags have tested a patch that is the sum
> of the two future patches, so I'd say it's OK to keep the R-by on both
> patches.
> 

Okay, I just wanted to confirm one point — when you mentioned R-by, are you 
referring to the Reviewed-by tag? I wanted to make sure I understood it 
correctly before carrying the tags forward in the next version. 🙂> Thanks for your patience. We'll get to the bottom of this issue! :)
> 
> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[Luca Ceresoli]

On Wed May 20, 2026 at 2:29 PM CEST, tessolveupstream wrote:

>>> Additionally, regarding the Tested-by tags you mentioned earlier,
>>> should I carry them forward to both patches, or would you prefer them
>>> only on the applicable patch?
>>
>> I'd say yes. People who sent these tags have tested a patch that is the sum
>> of the two future patches, so I'd say it's OK to keep the R-by on both
>> patches.
>>
>
> Okay, I just wanted to confirm one point — when you mentioned R-by, are you
> referring to the Reviewed-by tag? I wanted to make sure I understood it
> correctly before carrying the tags forward in the next version. 🙂> Thanks for your patience. We'll get to the bottom of this issue! :)

Oops, I wrote R-by but I meant Tested-by.

I don't think you received any other (Acked/Reviewed-by) tags.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output

[tessolveupstream]

On 20-05-2026 23:18, Luca Ceresoli wrote:
> On Wed May 20, 2026 at 2:29 PM CEST, tessolveupstream wrote:
> 
>>>> Additionally, regarding the Tested-by tags you mentioned earlier,
>>>> should I carry them forward to both patches, or would you prefer them
>>>> only on the applicable patch?
>>>
>>> I'd say yes. People who sent these tags have tested a patch that is the sum
>>> of the two future patches, so I'd say it's OK to keep the R-by on both
>>> patches.
>>>
>>
>> Okay, I just wanted to confirm one point — when you mentioned R-by, are you
>> referring to the Reviewed-by tag? I wanted to make sure I understood it
>> correctly before carrying the tags forward in the next version. 🙂> Thanks for your patience. We'll get to the bottom of this issue! :)
> 
> Oops, I wrote R-by but I meant Tested-by.
>

Thanks for the confirmation.
 
> I don't think you received any other (Acked/Reviewed-by) tags.
> 

Yes, I have not received any other Acked-by or Reviewed-by tags.

> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com