Re: [PATCH 11/18] drm/i915: switch to default context on idle

[Daniel Vetter <daniel@ffwll.ch>]

On Sun, Mar 18, 2012 at 01:39:51PM -0700, Ben Widawsky wrote:
> To keep things as sane as possible, switch to the default context before
> idling. This should help free context objects, as well as put things in
> a more well defined state before suspending.
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

Context are yet another thing that will nicely fragment our global gtt
space. You don't pin them to mappable, which is a start, but I wonder
whether we should integrate this into our evict_something code? Although
that project is more involved with the current evict code, so maybe just
add a fixme.

> ---
>  drivers/gpu/drm/i915/i915_gem.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 0985aa5..c1aab45 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3685,6 +3685,8 @@ int
>  i915_gem_idle(struct drm_device *dev)
>  {
>  	drm_i915_private_t *dev_priv = dev->dev_private;
> +	struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
> +	u32 seqno;
>  	int ret;
>  
>  	mutex_lock(&dev->struct_mutex);
> @@ -3694,6 +3696,10 @@ i915_gem_idle(struct drm_device *dev)
>  		return 0;
>  	}
>  
> +	seqno = i915_gem_next_request_seqno(ring);
> +	i915_switch_context(ring, NULL, DEFAULT_CONTEXT_ID, seqno, 0);
> +	WARN_ON(i915_wait_request(ring, seqno, false));

This can block and potentially return early due to a signal, i.e. you need
to properly handle this (like the i915_gpu_idle below).

> +
>  	ret = i915_gpu_idle(dev, true);
>  	if (ret) {
>  		mutex_unlock(&dev->struct_mutex);
> -- 
> 1.7.9.4
> 
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-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48