linux-kernel - Re: [PATCH] drm/udl: Increase get urb timeout for modeset

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Message-ID: <38110178-0f27-44ba-9925-5bbe74a1bf9b@suse.de>
Date: Wed, 5 Nov 2025 09:57:14 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: oushixiong1025@....com, Dave Airlie <airlied@...hat.com>
Cc: Sean Paul <sean@...rly.run>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, Shixiong Ou <oushixiong@...inos.cn>
Subject: Re: [PATCH] drm/udl: Increase get urb timeout for modeset

Hi

Am 05.11.25 um 09:30 schrieb oushixiong1025@....com:
> From: Shixiong Ou <oushixiong@...inos.cn>
>
> [WHY]
> There is a situation where udl_handle_damage() was running successfully
> but the screen was black. it was because udl_crtc_helper_atomic_enable() failed,
> and there were no error messages.
>
> [HOW]
> The priority for mode settings needs to be higher than damage handle, requiring
> a higher success rate than ordinary operations.
> Increase get urb timeout for modeset.
>
> Signed-off-by: Shixiong Ou <oushixiong@...inos.cn>
> ---
>   drivers/gpu/drm/udl/udl_drv.h      |  5 ++++-
>   drivers/gpu/drm/udl/udl_main.c     |  5 ++---
>   drivers/gpu/drm/udl/udl_modeset.c  | 11 +++++++----
>   drivers/gpu/drm/udl/udl_transfer.c |  2 +-
>   4 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
> index 145bb95ccc48..38b3bdf1ae4a 100644
> --- a/drivers/gpu/drm/udl/udl_drv.h
> +++ b/drivers/gpu/drm/udl/udl_drv.h
> @@ -31,6 +31,9 @@ struct drm_mode_create_dumb;
>   #define DRIVER_MINOR		0
>   #define DRIVER_PATCHLEVEL	1
>   
> +#define GET_URB_TIMEOUT	HZ
> +#define MODESET_GET_URB_TIMEOUT	(HZ*2)
> +

Just increase the regular GET_URB_TIMEOUT for all operations.

Best regards
Thomas

>   struct udl_device;
>   
>   struct urb_node {
> @@ -72,7 +75,7 @@ static inline struct usb_device *udl_to_usb_device(struct udl_device *udl)
>   int udl_modeset_init(struct udl_device *udl);
>   struct drm_connector *udl_connector_init(struct drm_device *dev);
>   
> -struct urb *udl_get_urb(struct udl_device *udl);
> +struct urb *udl_get_urb(struct udl_device *udl, long timeout);
>   
>   int udl_submit_urb(struct udl_device *udl, struct urb *urb, size_t len);
>   void udl_sync_pending_urbs(struct udl_device *udl);
> diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
> index bc58991a6f14..891996f0f74b 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 *udl_get_urb(struct udl_device *udl, long timeout)
>   {
>   	struct urb *urb;
>   
>   	spin_lock_irq(&udl->urbs.lock);
> -	urb = udl_get_urb_locked(udl, GET_URB_TIMEOUT);
> +	urb = udl_get_urb_locked(udl, timeout);
>   	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..6adca5e3e471 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>
>   
> @@ -217,7 +218,7 @@ static int udl_handle_damage(struct drm_framebuffer *fb,
>   		return ret;
>   	log_bpp = ret;
>   
> -	urb = udl_get_urb(udl);
> +	urb = udl_get_urb(udl, GET_URB_TIMEOUT);
>   	if (!urb)
>   		return -ENOMEM;
>   	cmd = urb->transfer_buffer;
> @@ -341,9 +342,11 @@ static void udl_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atom
>   	if (!drm_dev_enter(dev, &idx))
>   		return;
>   
> -	urb = udl_get_urb(udl);
> -	if (!urb)
> +	urb = udl_get_urb(udl, MODESET_GET_URB_TIMEOUT);
> +	if (!urb) {
> +		DRM_ERROR("Udl get urb failed when enabling crtc");
>   		goto out;
> +	}
>   
>   	buf = (char *)urb->transfer_buffer;
>   	buf = udl_vidreg_lock(buf);
> @@ -374,7 +377,7 @@ static void udl_crtc_helper_atomic_disable(struct drm_crtc *crtc, struct drm_ato
>   	if (!drm_dev_enter(dev, &idx))
>   		return;
>   
> -	urb = udl_get_urb(udl);
> +	urb = udl_get_urb(udl, MODESET_GET_URB_TIMEOUT);
>   	if (!urb)
>   		goto out;
>   
> diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
> index 7d670b3a5293..858b47522d78 100644
> --- a/drivers/gpu/drm/udl/udl_transfer.c
> +++ b/drivers/gpu/drm/udl/udl_transfer.c
> @@ -202,7 +202,7 @@ int udl_render_hline(struct udl_device *udl, int log_bpp, struct urb **urb_ptr,
>   			int ret = udl_submit_urb(udl, urb, len);
>   			if (ret)
>   				return ret;
> -			urb = udl_get_urb(udl);
> +			urb = udl_get_urb(udl, GET_URB_TIMEOUT);
>   			if (!urb)
>   				return -EAGAIN;
>   			*urb_ptr = urb;

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)