On 07.11.2017 16:11, Mikko Perttunen wrote: > On 05.11.2017 19:14, Dmitry Osipenko wrote: >> On 05.11.2017 14:01, Mikko Perttunen wrote: >>> 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. >>> >> >> Wouldn't it be more optimal to request channel and block after job's pining, >> when all patching and checks are completed? Note that right now we have locking >> around submission in DRM, which I suppose should go away by making locking fine >> grained. > > That would be possible, but I don't think it should matter much since contention > here should not be the common case. > >> >> Or maybe it would be more optimal to just iterate over channels, like I >> suggested before [0]? > > Somehow I hadn't noticed this before, but this would break the invariant of > having one client/class per channel. > Yes, currently there is a weak relation of channel and clients device, but seems channels device is only used for printing dev_* messages and device could be borrowed from the channels job. I don't see any real point of hardwiring channel to a specific device or client. > In general since we haven't seen any issues downstream with the model > implemented here, I'd like to try to go with this and if we have problems with > channel allocation then we could revisit. > I'd prefer to collect some real numbers first, will test it with our grate / mesa stuff. Also, we should have a host1x_test, maybe something similar to submission perf test but using multiple contexts. > >> >> [0] >> https://github.com/cyndis/linux/commit/9e6d87f40afb01fbe13ba65c73cb617bdfcd80b2#commitcomment-25012960 >> >> >>> Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx> >>> --- >>> 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); >>> >> -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
