openwrt/target/linux/bcm27xx/patches-6.6/950-1265-vc04_services-codec-Allocate-the-max-number-of-buffe.patch

From 8c9ca647449ba9df7e3b300c480242f9b5bdd867 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Tue, 10 Sep 2024 16:58:56 +0100
Subject: [PATCH 1265/1350] vc04_services: codec: Allocate the max number of
 buffers on the VPU

The VPU's API can't match the use of VIDIOC_CREATE_BUFS to add buffers
to the internal pool whilst a port is enabled, therefore allocate
the maximum number of buffers possible in V4L2 to avoid the issue.
As these are only buffer headers, the overhead is relatively small.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 .../vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c   | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/drivers/staging/vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c
+++ b/drivers/staging/vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c
@@ -2871,8 +2871,14 @@ static int bcm2835_codec_queue_setup(str
 
 	if (*nbuffers < port->minimum_buffer.num)
 		*nbuffers = port->minimum_buffer.num;
-	/* Add one buffer to take an EOS */
-	port->current_buffer.num = *nbuffers + 1;
+
+	/*
+	 * The VPU uses this number to allocate a pool of headers at port_enable.
+	 * We can't increase it later, so use of CREATE_BUFS is going to result
+	 * in bad things happening. Adopt worst-case allocation, and add one
+	 * buffer to take an EOS
+	 */
+	port->current_buffer.num = VB2_MAX_FRAME + 1;
 
 	return 0;
 }