[PATCH 10/10] gpu: host1x: Optionally block when acquiring channel
Mikko Perttunen
mperttunen at nvidia.com
Sun Nov 5 11:01:18 UTC 2017
Add an option to host1x_channel_request to interruptibly wait for a
free channel. This allows IOCTLs that acquire a channel to block
the userspace.
Signed-off-by: Mikko Perttunen <mperttunen at nvidia.com>
---
drivers/gpu/drm/tegra/drm.c | 9 +++++----
drivers/gpu/drm/tegra/gr2d.c | 6 +++---
drivers/gpu/drm/tegra/gr3d.c | 6 +++---
drivers/gpu/host1x/channel.c | 40 ++++++++++++++++++++++++++++++----------
drivers/gpu/host1x/channel.h | 1 +
include/linux/host1x.h | 2 +-
6 files changed, 43 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 658bc8814f38..19f77c1a76c0 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -389,7 +389,8 @@ static int host1x_waitchk_copy_from_user(struct host1x_waitchk *dest,
* Request a free hardware host1x channel for this user context, or if the
* context already has one, bump its refcount.
*
- * Returns 0 on success, or -EBUSY if there were no free hardware channels.
+ * Returns 0 on success, -EINTR if wait for a free channel was interrupted,
+ * or other error.
*/
int tegra_drm_context_get_channel(struct tegra_drm_context *context)
{
@@ -398,10 +399,10 @@ int tegra_drm_context_get_channel(struct tegra_drm_context *context)
mutex_lock(&context->lock);
if (context->pending_jobs == 0) {
- context->channel = host1x_channel_request(client->dev);
- if (!context->channel) {
+ context->channel = host1x_channel_request(client->dev, true);
+ if (IS_ERR(context->channel)) {
mutex_unlock(&context->lock);
- return -EBUSY;
+ return PTR_ERR(context->channel);
}
}
diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
index 3db3bcac48b9..c1853402f69b 100644
--- a/drivers/gpu/drm/tegra/gr2d.c
+++ b/drivers/gpu/drm/tegra/gr2d.c
@@ -32,9 +32,9 @@ static int gr2d_init(struct host1x_client *client)
unsigned long flags = HOST1X_SYNCPT_HAS_BASE;
struct gr2d *gr2d = to_gr2d(drm);
- gr2d->channel = host1x_channel_request(client->dev);
- if (!gr2d->channel)
- return -ENOMEM;
+ gr2d->channel = host1x_channel_request(client->dev, false);
+ if (IS_ERR(gr2d->channel))
+ return PTR_ERR(gr2d->channel);
client->syncpts[0] = host1x_syncpt_request(client->dev, flags);
if (!client->syncpts[0]) {
diff --git a/drivers/gpu/drm/tegra/gr3d.c b/drivers/gpu/drm/tegra/gr3d.c
index 279438342c8c..793a91d577cb 100644
--- a/drivers/gpu/drm/tegra/gr3d.c
+++ b/drivers/gpu/drm/tegra/gr3d.c
@@ -42,9 +42,9 @@ static int gr3d_init(struct host1x_client *client)
unsigned long flags = HOST1X_SYNCPT_HAS_BASE;
struct gr3d *gr3d = to_gr3d(drm);
- gr3d->channel = host1x_channel_request(client->dev);
- if (!gr3d->channel)
- return -ENOMEM;
+ gr3d->channel = host1x_channel_request(client->dev, false);
+ if (IS_ERR(gr3d->channel))
+ return PTR_ERR(gr3d->channel);
client->syncpts[0] = host1x_syncpt_request(client->dev, flags);
if (!client->syncpts[0]) {
diff --git a/drivers/gpu/host1x/channel.c b/drivers/gpu/host1x/channel.c
index 9d8cad12f9d8..eebcd51261df 100644
--- a/drivers/gpu/host1x/channel.c
+++ b/drivers/gpu/host1x/channel.c
@@ -43,6 +43,7 @@ int host1x_channel_list_init(struct host1x_channel_list *chlist,
bitmap_zero(chlist->allocated_channels, num_channels);
mutex_init(&chlist->lock);
+ sema_init(&chlist->sema, num_channels);
return 0;
}
@@ -99,6 +100,8 @@ static void release_channel(struct kref *kref)
host1x_cdma_deinit(&channel->cdma);
clear_bit(channel->id, chlist->allocated_channels);
+
+ up(&chlist->sema);
}
void host1x_channel_put(struct host1x_channel *channel)
@@ -107,19 +110,30 @@ void host1x_channel_put(struct host1x_channel *channel)
}
EXPORT_SYMBOL(host1x_channel_put);
-static struct host1x_channel *acquire_unused_channel(struct host1x *host)
+static struct host1x_channel *acquire_unused_channel(struct host1x *host,
+ bool wait)
{
struct host1x_channel_list *chlist = &host->channel_list;
unsigned int max_channels = host->info->nb_channels;
unsigned int index;
+ int err;
+
+ if (wait) {
+ err = down_interruptible(&chlist->sema);
+ if (err)
+ return ERR_PTR(err);
+ } else {
+ if (down_trylock(&chlist->sema))
+ return ERR_PTR(-EBUSY);
+ }
mutex_lock(&chlist->lock);
index = find_first_zero_bit(chlist->allocated_channels, max_channels);
- if (index >= max_channels) {
+ if (WARN(index >= max_channels, "failed to find free channel")) {
mutex_unlock(&chlist->lock);
dev_err(host->dev, "failed to find free channel\n");
- return NULL;
+ return ERR_PTR(-EBUSY);
}
chlist->channels[index].id = index;
@@ -134,20 +148,26 @@ static struct host1x_channel *acquire_unused_channel(struct host1x *host)
/**
* host1x_channel_request() - Allocate a channel
* @device: Host1x unit this channel will be used to send commands to
+ * @wait: Whether to wait for a free channels if all are reserved
+ *
+ * Allocates a new host1x channel for @device. If all channels are in use,
+ * and @wait is true, does an interruptible wait until one is available.
*
- * Allocates a new host1x channel for @device. May return NULL if CDMA
- * initialization fails.
+ * If a channel was acquired, returns a pointer to it. Otherwise returns
+ * an error pointer with -EINTR if the wait was interrupted, -EBUSY
+ * if a channel could not be acquired or another error code if channel
+ * initialization failed.
*/
-struct host1x_channel *host1x_channel_request(struct device *dev)
+struct host1x_channel *host1x_channel_request(struct device *dev, bool wait)
{
struct host1x *host = dev_get_drvdata(dev->parent);
struct host1x_channel_list *chlist = &host->channel_list;
struct host1x_channel *channel;
int err;
- channel = acquire_unused_channel(host);
- if (!channel)
- return NULL;
+ channel = acquire_unused_channel(host, wait);
+ if (IS_ERR(channel))
+ return channel;
kref_init(&channel->refcount);
mutex_init(&channel->submitlock);
@@ -168,6 +188,6 @@ struct host1x_channel *host1x_channel_request(struct device *dev)
dev_err(dev, "failed to initialize channel\n");
- return NULL;
+ return ERR_PTR(err);
}
EXPORT_SYMBOL(host1x_channel_request);
diff --git a/drivers/gpu/host1x/channel.h b/drivers/gpu/host1x/channel.h
index e68a8ae9a670..1f5cf8029b62 100644
--- a/drivers/gpu/host1x/channel.h
+++ b/drivers/gpu/host1x/channel.h
@@ -31,6 +31,7 @@ struct host1x_channel_list {
struct host1x_channel *channels;
struct mutex lock;
+ struct semaphore sema;
unsigned long *allocated_channels;
};
diff --git a/include/linux/host1x.h b/include/linux/host1x.h
index f931d28a68ff..2a34905d4408 100644
--- a/include/linux/host1x.h
+++ b/include/linux/host1x.h
@@ -171,7 +171,7 @@ u32 host1x_syncpt_base_id(struct host1x_syncpt_base *base);
struct host1x_channel;
struct host1x_job;
-struct host1x_channel *host1x_channel_request(struct device *dev);
+struct host1x_channel *host1x_channel_request(struct device *dev, bool wait);
struct host1x_channel *host1x_channel_get(struct host1x_channel *channel);
void host1x_channel_put(struct host1x_channel *channel);
int host1x_job_submit(struct host1x_job *job);
--
2.14.2
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