Re: [PATCH 1/9] drm/i915: Flush logical context image out to memory upon suspend

Mika Kuoppala
2016-07-15T10:42:18Z

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Before suspend, and especially before building the hibernation image, we
> need to context image to be coherent in memory. To do this we require
> that we perform a context switch to a disposable context (i.e. the
> dev_priv->kernel_context) - when that switch is complete, all other
> context images will be complete. This leaves the kernel_context image as
> incomplete, but fortunately that is disposable and we can do a quick
> fixup of the logical state after resuming.
>
> Testcase: igt/gem_exec_suspend # bsw
> References: https://bugs.freedesktop.org/show_bug.cgi?id=96526
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 4 +---
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_gem.c | 46 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 48 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 15440123e38d..c5b7b8e0678a 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1590,9 +1590,7 @@ static int i915_drm_resume(struct drm_device *dev)
>
> intel_csr_ucode_resume(dev_priv);
>
> - mutex_lock(&dev->struct_mutex);
> - i915_gem_restore_gtt_mappings(dev);
> - mutex_unlock(&dev->struct_mutex);
> + i915_gem_resume(dev);
>
> i915_restore_state(dev);
> intel_opregion_setup(dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 1ec523d29789..e73c0fc84c73 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3384,6 +3384,7 @@ void i915_gem_init_swizzling(struct drm_device *dev);
> void i915_gem_cleanup_engines(struct drm_device *dev);
> int __must_check i915_gem_wait_for_idle(struct drm_i915_private *dev_priv);
> int __must_check i915_gem_suspend(struct drm_device *dev);
> +void i915_gem_resume(struct drm_device *dev);
> void __i915_add_request(struct drm_i915_gem_request *req,
> struct drm_i915_gem_object *batch_obj,
> bool flush_caches);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index cf0e8aa8035c..8b42a5101f11 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4974,6 +4974,35 @@ i915_gem_stop_engines(struct drm_device *dev)
> dev_priv->gt.stop_engine(engine);
> }
>
> +static int switch_to_kernel_context(struct drm_i915_private *dev_priv)
> +{
> + struct intel_engine_cs *engine;
> +
> + for_each_engine(engine, dev_priv) {
> + struct drm_i915_gem_request *req;
> + int ret;
> +
> + if (engine->last_context == NULL)
> + continue;
> +
> + if (engine->last_context == dev_priv->kernel_context)
> + continue;
> +
> + req = i915_gem_request_alloc(engine, dev_priv->kernel_context);
> + if (IS_ERR(req))
> + return PTR_ERR(req);
> +
> + ret = 0;
> + if (!i915.enable_execlists)
> + ret = i915_switch_context(req);
> + i915_add_request_no_flush(req);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +

Why do you want keep this separate? Altho the evict one is a little
bit different and as I didn't see any perf implications: Why not
consolidate the evict one and this one and have i915_gem_idle which
would park to default and wait for idle.

Other than that, this all looks fine.

-Mika

> int
> i915_gem_suspend(struct drm_device *dev)
> {
> @@ -4983,6 +5012,10 @@ i915_gem_suspend(struct drm_device *dev)
> intel_suspend_gt_powersave(dev_priv);
>
> mutex_lock(&dev->struct_mutex);
> + ret = switch_to_kernel_context(dev_priv);
> + if (ret)
> + goto err;
> +
> ret = i915_gem_wait_for_idle(dev_priv);
> if (ret)
> goto err;
> @@ -5009,6 +5042,19 @@ err:
> return ret;
> }
>
> +void i915_gem_resume(struct drm_device *dev)
> +{
> + struct drm_i915_private *dev_priv = to_i915(dev);
> +
> + mutex_lock(&dev->struct_mutex);
> +
> + if (i915.enable_execlists)
> + intel_lr_context_reset(dev_priv, dev_priv->kernel_context);
> +
> + i915_gem_restore_gtt_mappings(dev);
> + mutex_unlock(&dev->struct_mutex);
> +}
> +
> void i915_gem_init_swizzling(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = to_i915(dev);
> --
> 2.8.1
>
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