FAILED: patch "[PATCH] drm/udl: Increase GET_URB_TIMEOUT" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x ac2c996675755c725a0065dbe3e2ebffded9080b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026051532-divisibly-poise-2b9c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ac2c996675755c725a0065dbe3e2ebffded9080b Mon Sep 17 00:00:00 2001
From: Shixiong Ou <oushixiong@kylinos.cn>
Date: Fri, 24 Apr 2026 20:44:27 +0800
Subject: [PATCH] drm/udl: Increase GET_URB_TIMEOUT

[WHY]
A situation has occurred where udl_handle_damage() executed successfully
and the kernel log appears normal, but the display fails to show any output.
This is because the call to udl_get_urb() in udl_crtc_helper_atomic_enable()
failed without generating any error message.

[HOW]
1. Increase timeout of getting urb.
2. Add error messages when calling udl_get_urb() failed in
udl_crtc_helper_atomic_enable().

Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 5320918b9a87 ("drm/udl: initial UDL driver (v4)")
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: <stable@vger.kernel.org> # v3.4+
Link: https://patch.msgid.link/20260424124427.657-1-oushixiong1025@163.com

diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
index 08a0e9480d70..17950fe3a0ec 100644
--- a/drivers/gpu/drm/udl/udl_main.c
+++ b/drivers/gpu/drm/udl/udl_main.c
@@ -285,13 +285,12 @@ static struct urb *udl_get_urb_locked(struct udl_device *udl, long timeout)
 	return unode->urb;
 }
 
-#define GET_URB_TIMEOUT	HZ
 struct urb *udl_get_urb(struct udl_device *udl)
 {
 	struct urb *urb;
 
 	spin_lock_irq(&udl->urbs.lock);
-	urb = udl_get_urb_locked(udl, GET_URB_TIMEOUT);
+	urb = udl_get_urb_locked(udl, HZ * 2);
 	spin_unlock_irq(&udl->urbs.lock);
 	return urb;
 }
diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index 231e829bd709..1ca073a4ecb2 100644
--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -21,6 +21,7 @@
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_vblank.h>
 
@@ -342,8 +343,10 @@ static void udl_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atom
 		return;
 
 	urb = udl_get_urb(udl);
-	if (!urb)
+	if (!urb) {
+		drm_err_ratelimited(dev, "get urb failed when enabling crtc\n");
 		goto out;
+	}
 
 	buf = (char *)urb->transfer_buffer;
 	buf = udl_vidreg_lock(buf);