[PATCH 08/10] drm/tegra: Implement dynamic channel allocation model
Dmitry Osipenko
digetx at gmail.com
Sun Nov 5 17:43:04 UTC 2017
On 05.11.2017 14:01, Mikko Perttunen wrote:
> In the traditional channel allocation model, a single hardware channel
> was allocated for each client. This is simple from an implementation
> perspective but prevents use of hardware scheduling.
>
> This patch implements a channel allocation model where when a user
> submits a job for a context, a hardware channel is allocated for
> that context. The same channel is kept for as long as there are
> incomplete jobs for that context. This way we can use hardware
> scheduling and channel isolation between userspace processes, but
> also prevent idling contexts from taking up hardware resources.
>
The dynamic channels resources (pushbuf) allocation is very expensive,
neglecting all benefits that this model should bring at least in non-IOMMU case.
We could have statically preallocated channels resources or defer resources freeing.
> For now, this patch only adapts VIC to the new model.
>
I think VIC's conversion should be a distinct patch.
> Signed-off-by: Mikko Perttunen <mperttunen at nvidia.com>
> ---
> drivers/gpu/drm/tegra/drm.c | 46 ++++++++++++++++++++++++++
> drivers/gpu/drm/tegra/drm.h | 7 +++-
> drivers/gpu/drm/tegra/vic.c | 79 +++++++++++++++++++++++----------------------
> 3 files changed, 92 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index b964e18e3058..658bc8814f38 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -382,6 +382,51 @@ static int host1x_waitchk_copy_from_user(struct host1x_waitchk *dest,
> return 0;
> }
>
> +/**
> + * tegra_drm_context_get_channel() - Get a channel for submissions
> + * @context: Context for which to get a channel for
> + *
> + * 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.
> + */
> +int tegra_drm_context_get_channel(struct tegra_drm_context *context)
> +{
> + struct host1x_client *client = &context->client->base;
> +
> + mutex_lock(&context->lock);
> +
> + if (context->pending_jobs == 0) {
> + context->channel = host1x_channel_request(client->dev);
> + if (!context->channel) {
> + mutex_unlock(&context->lock);
> + return -EBUSY;
> + }
> + }
> +
> + context->pending_jobs++;
> +
> + mutex_unlock(&context->lock);
> +
> + return 0;
> +}
> +
> +/**
> + * tegra_drm_context_put_channel() - Put a previously gotten channel
> + * @context: Context which channel is no longer needed
> + *
> + * Decrease the refcount of the channel associated with this context,
> + * freeing it if the refcount drops to zero.
> + */
> +void tegra_drm_context_put_channel(struct tegra_drm_context *context)
> +{
> + mutex_lock(&context->lock);
> + if (--context->pending_jobs == 0)
> + host1x_channel_put(context->channel);
> + mutex_unlock(&context->lock);
> +}
> +
> static void tegra_drm_job_done(struct host1x_job *job)
> {
> struct tegra_drm_context *context = job->callback_data;
> @@ -737,6 +782,7 @@ static int tegra_open_channel(struct drm_device *drm, void *data,
> kfree(context);
>
> kref_init(&context->ref);
> + mutex_init(&context->lock);
>
> mutex_unlock(&fpriv->lock);
> return err;
> diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
> index 11d690846fd0..d0c3f1f779f6 100644
> --- a/drivers/gpu/drm/tegra/drm.h
> +++ b/drivers/gpu/drm/tegra/drm.h
> @@ -78,9 +78,12 @@ struct tegra_drm_context {
> struct kref ref;
>
> struct tegra_drm_client *client;
> + unsigned int id;
> +
> + struct mutex lock;
> struct host1x_channel *channel;
> struct host1x_syncpt *syncpt;
> - unsigned int id;
> + unsigned int pending_jobs;
> };
>
> struct tegra_drm_client_ops {
> @@ -95,6 +98,8 @@ struct tegra_drm_client_ops {
> void (*submit_done)(struct tegra_drm_context *context);
> };
>
> +int tegra_drm_context_get_channel(struct tegra_drm_context *context);
> +void tegra_drm_context_put_channel(struct tegra_drm_context *context);
> int tegra_drm_submit(struct tegra_drm_context *context,
> struct drm_tegra_submit *args, struct drm_device *drm,
> struct drm_file *file);
> diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
> index efe5f3af933e..0cacf023a890 100644
> --- a/drivers/gpu/drm/tegra/vic.c
> +++ b/drivers/gpu/drm/tegra/vic.c
> @@ -33,7 +33,6 @@ struct vic {
>
> void __iomem *regs;
> struct tegra_drm_client client;
> - struct host1x_channel *channel;
> struct iommu_domain *domain;
> struct device *dev;
> struct clk *clk;
> @@ -161,28 +160,12 @@ static int vic_init(struct host1x_client *client)
> goto detach_device;
> }
>
> - vic->channel = host1x_channel_request(client->dev);
> - if (!vic->channel) {
> - err = -ENOMEM;
> - goto detach_device;
> - }
> -
> - client->syncpts[0] = host1x_syncpt_request(client->dev, 0);
> - if (!client->syncpts[0]) {
> - err = -ENOMEM;
> - goto free_channel;
> - }
> -
> err = tegra_drm_register_client(tegra, drm);
> if (err < 0)
> - goto free_syncpt;
> + goto detach_device;
>
> return 0;
>
> -free_syncpt:
> - host1x_syncpt_free(client->syncpts[0]);
> -free_channel:
> - host1x_channel_put(vic->channel);
> detach_device:
> if (tegra->domain)
> iommu_detach_device(tegra->domain, vic->dev);
> @@ -202,9 +185,6 @@ static int vic_exit(struct host1x_client *client)
> if (err < 0)
> return err;
>
> - host1x_syncpt_free(client->syncpts[0]);
> - host1x_channel_put(vic->channel);
> -
> if (vic->domain) {
> iommu_detach_device(vic->domain, vic->dev);
> vic->domain = NULL;
> @@ -221,7 +201,24 @@ static const struct host1x_client_ops vic_client_ops = {
> static int vic_open_channel(struct tegra_drm_client *client,
> struct tegra_drm_context *context)
> {
> - struct vic *vic = to_vic(client);
> + context->syncpt = host1x_syncpt_request(client->base.dev, 0);
> + if (!context->syncpt)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static void vic_close_channel(struct tegra_drm_context *context)
> +{
> + host1x_syncpt_free(context->syncpt);
> +}
> +
> +static int vic_submit(struct tegra_drm_context *context,
> + struct drm_tegra_submit *args, struct drm_device *drm,
> + struct drm_file *file)
> +{
> + struct host1x_client *client = &context->client->base;
> + struct vic *vic = dev_get_drvdata(client->dev);
> int err;
>
> err = pm_runtime_get_sync(vic->dev);
> @@ -229,35 +226,41 @@ static int vic_open_channel(struct tegra_drm_client *client,
> return err;
>
> err = vic_boot(vic);
> - if (err < 0) {
> - pm_runtime_put(vic->dev);
> - return err;
> - }
> + if (err < 0)
> + goto put_vic;
>
> - context->channel = host1x_channel_get(vic->channel);
> - if (!context->channel) {
> - pm_runtime_put(vic->dev);
> - return -ENOMEM;
> - }
> + err = tegra_drm_context_get_channel(context);
> + if (err < 0)
> + goto put_vic;
>
> - context->syncpt = client->base.syncpts[0];
> + err = tegra_drm_submit(context, args, drm, file);
> + if (err)
> + goto put_channel;
>
> return 0;
> +
> +put_channel:
> + tegra_drm_context_put_channel(context);
> +put_vic:
> + pm_runtime_put(vic->dev);
> +
> + return err;
> }
>
> -static void vic_close_channel(struct tegra_drm_context *context)
> +static void vic_submit_done(struct tegra_drm_context *context)
> {
> - struct vic *vic = to_vic(context->client);
> -
> - host1x_channel_put(context->channel);
> + struct host1x_client *client = &context->client->base;
> + struct vic *vic = dev_get_drvdata(client->dev);
>
> + tegra_drm_context_put_channel(context);
> pm_runtime_put(vic->dev);
> }
>
> static const struct tegra_drm_client_ops vic_ops = {
> .open_channel = vic_open_channel,
> .close_channel = vic_close_channel,
> - .submit = tegra_drm_submit,
> + .submit = vic_submit,
> + .submit_done = vic_submit_done,
> };
>
> #define NVIDIA_TEGRA_124_VIC_FIRMWARE "nvidia/tegra124/vic03_ucode.bin"
> @@ -340,8 +343,6 @@ static int vic_probe(struct platform_device *pdev)
> vic->client.base.ops = &vic_client_ops;
> vic->client.base.dev = dev;
> vic->client.base.class = HOST1X_CLASS_VIC;
> - vic->client.base.syncpts = syncpts;
> - vic->client.base.num_syncpts = 1;
> vic->dev = dev;
> vic->config = vic_config;
>
>
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