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Message-Id: <20220804075826.27036-2-tiwai@suse.de>
Date: Thu, 4 Aug 2022 09:58:23 +0200
From: Takashi Iwai <tiwai@...e.de>
To: dri-devel@...ts.freedesktop.org
Cc: Dave Airlie <airlied@...hat.com>, Sean Paul <sean@...rly.run>,
Thomas Zimmermann <tzimmermann@...e.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] drm/udl: Replace semaphore with a simple wait queue
UDL driver uses a semaphore for controlling the emptiness of FIFO in a
slightly funky way. This patch replaces it with a wait queue and
controls the emptiness with the standard wait_event*() macro instead,
which is a more straightforward implementation.
While we are at it, drop the dead code for delayed semaphore down,
too.
Tested-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
drivers/gpu/drm/udl/udl_drv.h | 11 +++--
drivers/gpu/drm/udl/udl_main.c | 84 ++++++++++------------------------
2 files changed, 31 insertions(+), 64 deletions(-)
diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
index cc16a13316e4..e008686ec738 100644
--- a/drivers/gpu/drm/udl/udl_drv.h
+++ b/drivers/gpu/drm/udl/udl_drv.h
@@ -34,14 +34,13 @@ struct udl_device;
struct urb_node {
struct list_head entry;
struct udl_device *dev;
- struct delayed_work release_urb_work;
struct urb *urb;
};
struct urb_list {
struct list_head list;
spinlock_t lock;
- struct semaphore limit_sem;
+ wait_queue_head_t sleep;
int available;
int count;
size_t size;
@@ -75,7 +74,13 @@ static inline struct usb_device *udl_to_usb_device(struct udl_device *udl)
int udl_modeset_init(struct drm_device *dev);
struct drm_connector *udl_connector_init(struct drm_device *dev);
-struct urb *udl_get_urb(struct drm_device *dev);
+struct urb *udl_get_urb_timeout(struct drm_device *dev, long timeout);
+
+#define GET_URB_TIMEOUT HZ
+static inline struct urb *udl_get_urb(struct drm_device *dev)
+{
+ return udl_get_urb_timeout(dev, GET_URB_TIMEOUT);
+}
int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len);
void udl_urb_completion(struct urb *urb);
diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
index 853f147036f6..67fd41e59b80 100644
--- a/drivers/gpu/drm/udl/udl_main.c
+++ b/drivers/gpu/drm/udl/udl_main.c
@@ -23,9 +23,6 @@
#define WRITES_IN_FLIGHT (4)
#define MAX_VENDOR_DESCRIPTOR_SIZE 256
-#define GET_URB_TIMEOUT HZ
-#define FREE_URB_TIMEOUT (HZ*2)
-
static int udl_parse_vendor_descriptor(struct udl_device *udl)
{
struct usb_device *udev = udl_to_usb_device(udl);
@@ -119,14 +116,6 @@ static int udl_select_std_channel(struct udl_device *udl)
return ret < 0 ? ret : 0;
}
-static void udl_release_urb_work(struct work_struct *work)
-{
- struct urb_node *unode = container_of(work, struct urb_node,
- release_urb_work.work);
-
- up(&unode->dev->urbs.limit_sem);
-}
-
void udl_urb_completion(struct urb *urb)
{
struct urb_node *unode = urb->context;
@@ -150,23 +139,13 @@ void udl_urb_completion(struct urb *urb)
udl->urbs.available++;
spin_unlock_irqrestore(&udl->urbs.lock, flags);
-#if 0
- /*
- * When using fb_defio, we deadlock if up() is called
- * while another is waiting. So queue to another process.
- */
- if (fb_defio)
- schedule_delayed_work(&unode->release_urb_work, 0);
- else
-#endif
- up(&udl->urbs.limit_sem);
+ wake_up(&udl->urbs.sleep);
}
static void udl_free_urb_list(struct drm_device *dev)
{
struct udl_device *udl = to_udl(dev);
int count = udl->urbs.count;
- struct list_head *node;
struct urb_node *unode;
struct urb *urb;
@@ -174,23 +153,15 @@ static void udl_free_urb_list(struct drm_device *dev)
/* keep waiting and freeing, until we've got 'em all */
while (count--) {
- down(&udl->urbs.limit_sem);
-
- spin_lock_irq(&udl->urbs.lock);
-
- node = udl->urbs.list.next; /* have reserved one with sem */
- list_del_init(node);
-
- spin_unlock_irq(&udl->urbs.lock);
-
- unode = list_entry(node, struct urb_node, entry);
- urb = unode->urb;
-
+ urb = udl_get_urb_timeout(dev, MAX_SCHEDULE_TIMEOUT);
+ if (WARN_ON(!urb))
+ break;
+ unode = urb->context;
/* Free each separately allocated piece */
usb_free_coherent(urb->dev, udl->urbs.size,
urb->transfer_buffer, urb->transfer_dma);
usb_free_urb(urb);
- kfree(node);
+ kfree(unode);
}
udl->urbs.count = 0;
}
@@ -210,7 +181,7 @@ static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
udl->urbs.size = size;
INIT_LIST_HEAD(&udl->urbs.list);
- sema_init(&udl->urbs.limit_sem, 0);
+ init_waitqueue_head(&udl->urbs.sleep);
udl->urbs.count = 0;
udl->urbs.available = 0;
@@ -220,9 +191,6 @@ static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
break;
unode->dev = udl;
- INIT_DELAYED_WORK(&unode->release_urb_work,
- udl_release_urb_work);
-
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
kfree(unode);
@@ -250,7 +218,6 @@ static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
list_add_tail(&unode->entry, &udl->urbs.list);
- up(&udl->urbs.limit_sem);
udl->urbs.count++;
udl->urbs.available++;
}
@@ -260,36 +227,31 @@ static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
return udl->urbs.count;
}
-struct urb *udl_get_urb(struct drm_device *dev)
+struct urb *udl_get_urb_timeout(struct drm_device *dev, long timeout)
{
struct udl_device *udl = to_udl(dev);
- int ret = 0;
- struct list_head *entry;
- struct urb_node *unode;
- struct urb *urb = NULL;
+ struct urb_node *unode = NULL;
- /* Wait for an in-flight buffer to complete and get re-queued */
- ret = down_timeout(&udl->urbs.limit_sem, GET_URB_TIMEOUT);
- if (ret) {
- DRM_INFO("wait for urb interrupted: %x available: %d\n",
- ret, udl->urbs.available);
- goto error;
- }
+ if (!udl->urbs.count)
+ return NULL;
+ /* Wait for an in-flight buffer to complete and get re-queued */
spin_lock_irq(&udl->urbs.lock);
+ if (!wait_event_lock_irq_timeout(udl->urbs.sleep,
+ !list_empty(&udl->urbs.list),
+ udl->urbs.lock, timeout)) {
+ DRM_INFO("wait for urb interrupted: available: %d\n",
+ udl->urbs.available);
+ goto unlock;
+ }
- BUG_ON(list_empty(&udl->urbs.list)); /* reserved one with limit_sem */
- entry = udl->urbs.list.next;
- list_del_init(entry);
+ unode = list_first_entry(&udl->urbs.list, struct urb_node, entry);
+ list_del_init(&unode->entry);
udl->urbs.available--;
+unlock:
spin_unlock_irq(&udl->urbs.lock);
-
- unode = list_entry(entry, struct urb_node, entry);
- urb = unode->urb;
-
-error:
- return urb;
+ return unode ? unode->urb : NULL;
}
int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len)
--
2.35.3
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