linux-kernel - Re: [PATCH 0/2] drm/atomic-helper: Support atomic flush with an optional kthread worker

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Message-ID: <e4704da5-2532-4559-b0a5-58ebf087681e@nxp.com>
Date: Mon, 8 Dec 2025 15:38:15 +0800
From: Liu Ying <victor.liu@....com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/2] drm/atomic-helper: Support atomic flush with an
 optional kthread worker

On 10/31/2025, Liu Ying wrote:
> Hi,
> 
> As drm_atomic_helper_commit_planes() calls atomic_flush for CRTCs
> sequentially and a driver's atomic_flush callback could be blocking,
> the performance for flushing multiple CRTCs in a single atomic commit
> could be low, like page flip for multiple CRTCs.  A real case is imx8-dc,
> which supports two CRTCs and does atomic_flush in a blocking way, i.e.,
> waits for a done event for loading shadow registers.
> 
> To resolve that, introduce an optional kthread worker to conduct
> flush in drm_atomic_helper_commit_planes(), so that flush can run in
> parallel for multiple CRTCs.
> 
> Drivers should call drmm_crtc_flush_worker_init() to initialize the
> kthread worker if they want to use it.
> 
> Patch 1 adds the optional kthread worker support.
> Patch 2 makes imx8-dc use the kthread worker.
> 
> Let me know your thoughts.  Thanks.

Gentle ping for review.

> 
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
> Liu Ying (2):
>       drm/atomic-helper: Support atomic flush with an optional kthread worker
>       drm/imx: dc-crtc: Use flush worker
> 
>  drivers/gpu/drm/drm_atomic_helper.c | 27 ++++++++++++++++-
>  drivers/gpu/drm/drm_crtc.c          | 59 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/imx/dc/dc-crtc.c    |  9 +++++-
>  include/drm/drm_crtc.h              | 45 ++++++++++++++++++++++++++++
>  4 files changed, 138 insertions(+), 2 deletions(-)
> ---
> base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa
> change-id: 20251031-drm-crtc-flush-worker-0aac27acf40f
> 
> Best regards,

-- 
Regards,
Liu Ying