From: John Harrison <John.Harrison@Igalia.com>
To: "Kandpal, Suraj" <suraj.kandpal@intel.com>,
"intel-xe@lists.freedesktop.org" <intel-xe@lists.freedesktop.org>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>
Cc: "S, Sowmiya" <sowmiya.s@intel.com>,
"Shankar, Uma" <uma.shankar@intel.com>,
"Sharma, Swati2" <swati2.sharma@intel.com>,
"Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>,
"Murthy, Arun R" <arun.r.murthy@intel.com>,
"kernel-dev@igalia.com" <kernel-dev@igalia.com>,
Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Subject: Re: [PATCH v3 00/26] Enable Pipe writeback
Date: Thu, 30 Apr 2026 13:11:49 -0700 [thread overview]
Message-ID: <f9a6f3d2-847b-407e-a744-a14346575581@Igalia.com> (raw)
In-Reply-To: <DM3PPF208195D8D07AFB5DBC81A0AA9540FE3352@DM3PPF208195D8D.namprd11.prod.outlook.com>
On 4/29/26 19:54, Kandpal, Suraj wrote:
>> On 3/25/26 04:07, Suraj Kandpal wrote:
>>> This series aims to enable pipe writeback functionality on ADLP where
>>> it has been tested. The plan is to slowly accomodate all supported
>>> hardware after this functionality is tested on them.
>>> This series currently sits on top of two series still under review in
>>> drm core. They are squashed as the first two patches of this series.
>>> This series enables the triggered captured mode where we need to
>>> trigger a capture.
>>>
>>> v2
>>> - Do required changes to take into account the new drm writeback
>>> framework
>>>
>>> v3
>>> - Fix patch series to apply cleanly
>>>
>>> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
>> Hello,
>>
>> I tried this out (on a LNL because I don't have an ADL at the moment) and hit a
>> bunch of issues with null pointer dereferences.
>>
>> It looks like the intel_writeback_connector::job field is never filled in but it is
>> being used. Further, it looks like that field exists because conn_state-
>>> writeback_job is gone by the time the capture function is called. However, the
>> capture function is still using that null job pointer instead of caching the
>> required info in the intel specific structure.
>>
>> Specifically, in intel_writeback_atomic_commit() it says:
>> drm_writeback_queue_job(connector, conn_state);
>> intel_writeback_capture(state, intel_connector);
>>
>> And the doc for the drm call explicitly says it clears the writeback_job field that
>> the capture function tries to use.
>>
>> I made the attached changes to my local tree and I no longer get any kernel
>> panics. I do get a "flip_done timed out" followed by a bunch of warns along the
>> lines of "attached crtc is active, but connector isn't".
>> I'm guessing this is related to running on unsupported hardware? What would
>> be needed to enable this for LNL?
> Hi John,
> currently this series is just a redesigned version to check if the expected changes in DRM core works with our design, there are some flaws that creeped in due to this. Currently this is not up on my priority list because there are two series mentioned in cover letter which are still not totally Rb'd stopping me from looking into this series and fixing it back up. If you can have the look at those DRM changes and Rb them.
The first pre-req patch set is this one from Dmitry, yes?
https://lore.kernel.org/dri-devel/20251228-wb-drop-encoder-v4-0-58d28e668901@oss.qualcomm.com/
AFAICT, it is mostly reviewed but there are two outstanding comments
along the lines of 'please explain why'. However, it has not been
touched since last December. Is Dmitry still working on this? If not,
would you be able to repost with the requested explanations? I don't
think that is something I can really comment on as I don't know all the
background here. Indeed, that's the kind of questions I would have asked
if I were to review the patches!
> There are some more changes that LNL requires to get writeback working.
Like a few tweaks or some significant new work?
Thanks,
John.
>
> Regards,
> Suraj Kandpal
>
>>
>>
>> Thanks,
>> John.
next prev parent reply other threads:[~2026-04-30 20:12 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-25 11:07 [PATCH v3 00/26] Enable Pipe writeback Suraj Kandpal
2026-03-25 11:07 ` [PATCH v3 DO NOT REVIEW 01/26] drm: writeback: rename drm_writeback_connector_init_with_encoder() Suraj Kandpal
2026-03-25 11:07 ` [PATCH v3 DO NOT REVIEW 02/26] drm: writeback: Refactor drm_writeback_connector structure Suraj Kandpal
2026-03-25 11:07 ` [PATCH v3 03/26] drm/i915/writeback: Add writeback registers Suraj Kandpal
2026-03-25 11:42 ` Ville Syrjälä
2026-03-26 2:31 ` Kandpal, Suraj
2026-03-31 7:12 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 04/26] drm/i915/writeback: Add some preliminary writeback definitions Suraj Kandpal
2026-03-25 11:52 ` Ville Syrjälä
2026-03-26 2:37 ` Kandpal, Suraj
2026-03-31 7:13 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 05/26] drm/i915/writeback: Init writeback connector Suraj Kandpal
2026-03-25 12:15 ` Ville Syrjälä
2026-03-26 2:52 ` Kandpal, Suraj
2026-03-31 7:13 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 06/26] drm/i915/writeback: Add function to get modes Suraj Kandpal
2026-03-31 7:14 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 07/26] drm/i915/writeback: Add hook to check modes Suraj Kandpal
2026-03-25 11:07 ` [PATCH v3 08/26] drm/i915/writeback: Define encoder->get_hw_state Suraj Kandpal
2026-03-25 12:08 ` Ville Syrjälä
2026-03-31 7:15 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 09/26] drm/i915/writeback: Fill encoder->get_config Suraj Kandpal
2026-03-25 12:15 ` Ville Syrjälä
2026-03-26 2:52 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 10/26] drm/i915/writeback: Add private structure for writeback job Suraj Kandpal
2026-03-25 12:17 ` Ville Syrjälä
2026-03-26 2:53 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 11/26] drm/i915/writeback: Define function for prepare and cleanup hooks Suraj Kandpal
2026-03-25 12:29 ` Ville Syrjälä
2026-03-25 11:07 ` [PATCH v3 12/26] drm/i915/writeback: Define compute_config for writeback Suraj Kandpal
2026-03-25 12:19 ` Ville Syrjälä
2026-03-26 3:38 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 13/26] drm/i915/writeback: Define function for connector function detect Suraj Kandpal
2026-03-25 12:22 ` Ville Syrjälä
2026-03-25 11:07 ` [PATCH v3 14/26] drm/i915/writeback: Define function to destroy writeback connector Suraj Kandpal
2026-03-25 12:23 ` Ville Syrjälä
2026-03-26 3:39 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 15/26] drm/i915/writeback: Add connector atomic check Suraj Kandpal
2026-03-25 12:25 ` Ville Syrjälä
2026-03-26 3:43 ` Kandpal, Suraj
2026-03-31 7:16 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 16/26] drm/i915/writeback: Add writeback to xe Makefile Suraj Kandpal
2026-03-25 12:25 ` Ville Syrjälä
2026-03-26 3:44 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 17/26] drm/i915/writeback: Add the enable sequence from writeback Suraj Kandpal
2026-03-25 12:31 ` Ville Syrjälä
2026-03-31 7:16 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 18/26] drm/i915/writeback: Define writeback frame capture function Suraj Kandpal
2026-03-25 12:33 ` Ville Syrjälä
2026-03-26 3:47 ` Kandpal, Suraj
2026-04-07 8:28 ` Jani Nikula
2026-04-08 3:02 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 19/26] drm/{i915/xe}/writeback: Add a writeback helper to get ggtt address Suraj Kandpal
2026-03-31 7:25 ` Borah, Chaitanya Kumar
2026-04-07 8:32 ` Jani Nikula
2026-04-08 3:24 ` Kandpal, Suraj
2026-04-08 4:11 ` Kandpal, Suraj
2026-03-25 11:07 ` [PATCH v3 20/26] drm/i915/writeback: Configure WD_STRIDE reg Suraj Kandpal
2026-03-25 12:35 ` Ville Syrjälä
2026-03-26 3:52 ` Kandpal, Suraj
2026-03-31 7:17 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 21/26] drm/i915/writeback: Configure WD_SURF register Suraj Kandpal
2026-03-31 7:17 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 22/26] drm/i915/writeback: Enable writeback interrupts Suraj Kandpal
2026-03-25 12:59 ` Ville Syrjälä
2026-03-31 7:19 ` Borah, Chaitanya Kumar
2026-04-07 8:36 ` Jani Nikula
2026-03-25 11:07 ` [PATCH v3 23/26] drm/i915/writeback: Initialize writeback encoder Suraj Kandpal
2026-03-25 13:00 ` Ville Syrjälä
2026-03-26 4:01 ` Kandpal, Suraj
2026-03-31 7:23 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 24/26] drm/i915/writeback: Define the disable sequence for writeback Suraj Kandpal
2026-03-31 7:20 ` Borah, Chaitanya Kumar
2026-03-25 11:07 ` [PATCH v3 25/26] drm/i915/writeback: Make exception for writeback connector Suraj Kandpal
2026-03-31 7:20 ` Borah, Chaitanya Kumar
2026-04-07 8:40 ` Jani Nikula
2026-03-25 11:07 ` [PATCH v3 26/26] drm/i915/writeback: Modify state verify function Suraj Kandpal
2026-03-25 13:01 ` Ville Syrjälä
2026-03-26 3:57 ` Kandpal, Suraj
2026-03-25 11:19 ` ✗ CI.checkpatch: warning for Enable Pipe writeback (rev3) Patchwork
2026-03-25 11:20 ` ✓ CI.KUnit: success " Patchwork
2026-04-29 21:27 ` [PATCH v3 00/26] Enable Pipe writeback John Harrison
2026-04-30 2:54 ` Kandpal, Suraj
2026-04-30 20:11 ` John Harrison [this message]
2026-05-20 23:58 ` John Harrison
2026-05-21 2:51 ` Kandpal, Suraj
2026-05-20 23:58 ` [PATCH 1/9] drm/i915/writeback: Fix null pointer problems with writeback jobs John Harrison
2026-05-20 23:58 ` [PATCH 2/9] drm/i915/display: Use an unbound workqueue for atomic clean up John Harrison
2026-05-27 9:12 ` Marco Crivellari
2026-05-20 23:58 ` [PATCH 3/9] drm/i915/display: Fail writeback setup if no transcoder offsets defined John Harrison
2026-05-20 23:58 ` [PATCH 4/9] drm/i915/display: Add writeback transcoder offsets for DG2 family John Harrison
2026-05-20 23:58 ` [PATCH 5/9] drm/i915/display: Disable pixel_rate check for writeback John Harrison
2026-05-20 23:58 ` [PATCH 6/9] drm/i915/display: Fix vblank wait timed out with writeback John Harrison
2026-05-20 23:58 ` [PATCH 7/9] drm/i915/display: Fix XBGR2101010 bpc John Harrison
2026-05-20 23:58 ` [PATCH 8/9] drm/i915/display: Ensure only supported writeback modes pass John Harrison
2026-05-20 23:58 ` [PATCH 9/9] drm/i915/writeback: Enable for more hardware than ADL John Harrison
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