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Message-ID: <ce11235b-47cb-43f1-86e9-dcebc7a0b35d@suse.de>
Date: Wed, 5 Nov 2025 10:38:48 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: oushixiong <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 10:07 schrieb oushixiong:
> If the wait times for all operations increase, it would likely cause
> significant blocking in the display process.
But we're usually not waiting until timeout, but only until the next urb
becomes available again. And we have several in the queue pre-allocated.
Increasing the timeout should therefore not be a problem. The current
drawing timeout of 1 second (== HZ) would already be a major issue
otherwise.
> Should we make a distinction between the two, or base it on what you
> said about increasing the regular GET_URB_TIMEOUT for all operations ?
Please try to double the timeout.
(If this really doesn't work, we should try to drop the urb caching
entirely and allocate urbs as we need them.)
Best regards
Thomas
>
> Best regards
> Shixiong
>
> 在 2025/11/5 16:57, Thomas Zimmermann 写道:
>> 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)
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