linux-kernel - [PATCH 6/7] RFC: v4l2-mem2mem: Remove warning from v4l2_m2m_job

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Message-Id: <20241220-media-rpi-hevc-dec-v1-6-0ebcc04ed42e@raspberrypi.com>
Date: Fri, 20 Dec 2024 16:21:17 +0000
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Florian Fainelli <florian.fainelli@...adcom.com>, 
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
 John Cox <john.cox@...pberrypi.com>, Dom Cobley <dom@...pberrypi.com>, 
 review list <kernel-list@...pberrypi.com>, 
 Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
Cc: John Cox <jc@...esim.co.uk>, linux-media@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-rpi-kernel@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>
Subject: [PATCH 6/7] RFC: v4l2-mem2mem: Remove warning from
 v4l2_m2m_job_finish

From: John Cox <john.cox@...pberrypi.com>

The Raspberry Pi HEVC decoder has a 2 stage pipeline
where the OUTPUT buffer is finished with before the
CAPTURE buffer is ready.

v4l2_m2m_job_finish allows us to do this, however as
the driver handles VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF,
this warn fires on every buffer as drivers that hold capture
buffers are expected to use v4l2_m2m_buf_done_and_job_finish
(introduced with [1]).
That doesn't allow us to handle not returning the destination
buffer.

[1] Commit f8cca8c97a63 ("media: v4l2-mem2mem: support held
capture buffers")

Signed-off-by: John Cox <john.cox@...pberrypi.com>
Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index eb22d6172462..325a518beff7 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -490,13 +490,6 @@ void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
 	unsigned long flags;
 	bool schedule_next;
 
-	/*
-	 * This function should not be used for drivers that support
-	 * holding capture buffers. Those should use
-	 * v4l2_m2m_buf_done_and_job_finish() instead.
-	 */
-	WARN_ON(m2m_ctx->out_q_ctx.q.subsystem_flags &
-		VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF);
 	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
 	schedule_next = _v4l2_m2m_job_finish(m2m_dev, m2m_ctx);
 	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);

-- 
2.34.1