linux-kernel - [PATCH] Revert "media: uvcvideo: Remove nodrop parameter"

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Message-Id: <20260113-uvc-revert-v1-1-0a873393774c@chromium.org>
Date: Tue, 13 Jan 2026 13:29:46 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hansg@...nel.org>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ralf Jung <post@...fj.de>, Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH] Revert "media: uvcvideo: Remove nodrop parameter"

This reverts commit 27ccc44a511b0cd76dc607e2a4893b876192ee1b.

A user has reported that the Zoom Video Conferencing tool is not capable
of handling invalid frames. Due to this, he has to continue using this
parameter.

We will keep working with Zoom so they can handle invalid frames
correctly, but for this cycle the safest option is to revert this
parameter drop.

Fixes: 27ccc44a511b ("media: uvcvideo: Remove nodrop parameter")
Reported-by: Ralf Jung <post@...fj.de>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1121718
Closes: https://lore.kernel.org/linux-media/uboug5ectzm4s32yfgopjbcxq2uhsoc4kluaby7a4b7nzfjave@boco7oocnftr/
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 19 +++++++++++++++++++
 drivers/media/usb/uvc/uvc_queue.c  | 25 +++++++++++++++++++++++++
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 3 files changed, 45 insertions(+)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 71563d8f4bcf581694ccd4b665ff52b629caa0b6..ee4f54d6834962414979a046afc59c5036455124 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -32,6 +32,7 @@
 
 unsigned int uvc_clock_param = CLOCK_MONOTONIC;
 unsigned int uvc_hw_timestamps_param;
+unsigned int uvc_no_drop_param = 1;
 static unsigned int uvc_quirks_param = -1;
 unsigned int uvc_dbg_param;
 unsigned int uvc_timeout_param = UVC_CTRL_STREAMING_TIMEOUT;
@@ -2467,6 +2468,24 @@ MODULE_PARM_DESC(clock, "Video buffers timestamp clock");
 module_param_named(hwtimestamps, uvc_hw_timestamps_param, uint, 0644);
 MODULE_PARM_DESC(hwtimestamps, "Use hardware timestamps");
 
+static int param_set_nodrop(const char *val, const struct kernel_param *kp)
+{
+	pr_warn_once("uvcvideo: "
+		     DEPRECATED
+		     "nodrop parameter will be eventually removed.\n");
+	return param_set_bool(val, kp);
+}
+
+static const struct kernel_param_ops param_ops_nodrop = {
+	.set = param_set_nodrop,
+	.get = param_get_uint,
+};
+
+param_check_uint(nodrop, &uvc_no_drop_param);
+module_param_cb(nodrop, &param_ops_nodrop, &uvc_no_drop_param, 0644);
+__MODULE_PARM_TYPE(nodrop, "uint");
+MODULE_PARM_DESC(nodrop, "Don't drop incomplete frames");
+
 module_param_named(quirks, uvc_quirks_param, uint, 0644);
 MODULE_PARM_DESC(quirks, "Forced device quirks");
 module_param_named(trace, uvc_dbg_param, uint, 0644);
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 3bc54456b4d98ed50b1ea250ce8501e67141e1ef..681a74ed09fb1f109d2b21bf490e8b26eeec0a3e 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -331,9 +331,34 @@ struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue)
 	return nextbuf;
 }
 
+/*
+ * uvc_queue_buffer_requeue: Requeue a buffer on our internal irqqueue
+ *
+ * Reuse a buffer through our internal queue without the need to 'prepare'.
+ * The buffer will be returned to userspace through the uvc_buffer_queue call if
+ * the device has been disconnected.
+ */
+static void uvc_queue_buffer_requeue(struct uvc_video_queue *queue,
+				     struct uvc_buffer *buf)
+{
+	buf->error = 0;
+	buf->state = UVC_BUF_STATE_QUEUED;
+	buf->bytesused = 0;
+	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);
+
+	uvc_buffer_queue(&buf->buf.vb2_buf);
+}
+
 static void uvc_queue_buffer_complete(struct kref *ref)
 {
 	struct uvc_buffer *buf = container_of(ref, struct uvc_buffer, ref);
+	struct vb2_buffer *vb = &buf->buf.vb2_buf;
+	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
+
+	if (buf->error && !uvc_no_drop_param) {
+		uvc_queue_buffer_requeue(queue, buf);
+		return;
+	}
 
 	buf->state = buf->error ? UVC_BUF_STATE_ERROR : UVC_BUF_STATE_DONE;
 	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, buf->bytesused);
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 911016047687f7c74fa1bf0dd0ecf2d072361346..d583425893a5f716185153a07aae9bfe20182964 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -659,6 +659,7 @@ static inline struct uvc_fh *to_uvc_fh(struct file *filp)
 #define UVC_WARN_XU_GET_RES	2
 
 extern unsigned int uvc_clock_param;
+extern unsigned int uvc_no_drop_param;
 extern unsigned int uvc_dbg_param;
 extern unsigned int uvc_timeout_param;
 extern unsigned int uvc_hw_timestamps_param;

---
base-commit: 3aa9296a23ec41a8424e9a2346eea59fb6cb7d8c
change-id: 20260113-uvc-revert-cd60dc7f16ec

Best regards,
-- 
Ricardo Ribalda <ribalda@...omium.org>