Re: [PATCH 3/9] drm/i915: fixup up debugfs rps state handling

[Ben Widawsky <ben@bwidawsk.net>]

On Tue, 24 Jul 2012 23:33:44 +0200
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> - Take the dev->struct_mutex around access the corresponding state
>   (and adjusting the rps hw state).
> - Add an assert to gen6_set_rps to ensure we don't forget about this
>   in the future.
> - Don't set up the min/max_freq files if it doesn't apply to the hw.
>   And do the same for the gen6+ cache sharing file while at it.
> 
> v2: Move the gen6+ checks into the read/write callbacks. Thanks to the
> awesome drm midlayer we can't check this when registering the debugfs
> files, because the driver is not yet fully set up, specifically the
> ->load callback hasn't run yet.
> 
> Oh how I despise & loathe this disaster ...
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

I think it's wise to use some kind of HAS_RPS() macro, but otherwise:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c |   27 +++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_pm.c     |    2 ++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 1312b79..2499610 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -1710,8 +1710,13 @@ i915_max_freq_read(struct file *filp,
>  	char buf[80];
>  	int len;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
> +	mutex_lock(&dev->struct_mutex);
>  	len = snprintf(buf, sizeof(buf),
>  		       "max freq: %d\n", dev_priv->max_delay * 50);
> +	mutex_unlock(&dev->struct_mutex);
>  
>  	if (len > sizeof(buf))
>  		len = sizeof(buf);
> @@ -1730,6 +1735,9 @@ i915_max_freq_write(struct file *filp,
>  	char buf[20];
>  	int val = 1;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
>  	if (cnt > 0) {
>  		if (cnt > sizeof(buf) - 1)
>  			return -EINVAL;
> @@ -1743,12 +1751,14 @@ i915_max_freq_write(struct file *filp,
>  
>  	DRM_DEBUG_DRIVER("Manually setting max freq to %d\n", val);
>  
> +	mutex_lock(&dev->struct_mutex);
>  	/*
>  	 * Turbo will still be enabled, but won't go above the set value.
>  	 */
>  	dev_priv->max_delay = val / 50;
>  
>  	gen6_set_rps(dev, val / 50);
> +	mutex_unlock(&dev->struct_mutex);
>  
>  	return cnt;
>  }
> @@ -1770,8 +1780,13 @@ i915_min_freq_read(struct file *filp, char __user *ubuf, size_t max,
>  	char buf[80];
>  	int len;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
> +	mutex_lock(&dev->struct_mutex);
>  	len = snprintf(buf, sizeof(buf),
>  		       "min freq: %d\n", dev_priv->min_delay * 50);
> +	mutex_unlock(&dev->struct_mutex);
>  
>  	if (len > sizeof(buf))
>  		len = sizeof(buf);
> @@ -1788,6 +1803,9 @@ i915_min_freq_write(struct file *filp, const char __user *ubuf, size_t cnt,
>  	char buf[20];
>  	int val = 1;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
>  	if (cnt > 0) {
>  		if (cnt > sizeof(buf) - 1)
>  			return -EINVAL;
> @@ -1801,12 +1819,14 @@ i915_min_freq_write(struct file *filp, const char __user *ubuf, size_t cnt,
>  
>  	DRM_DEBUG_DRIVER("Manually setting min freq to %d\n", val);
>  
> +	mutex_lock(&dev->struct_mutex);
>  	/*
>  	 * Turbo will still be enabled, but won't go below the set value.
>  	 */
>  	dev_priv->min_delay = val / 50;
>  
>  	gen6_set_rps(dev, val / 50);
> +	mutex_unlock(&dev->struct_mutex);
>  
>  	return cnt;
>  }
> @@ -1831,6 +1851,9 @@ i915_cache_sharing_read(struct file *filp,
>  	u32 snpcr;
>  	int len;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
>  	mutex_lock(&dev_priv->dev->struct_mutex);
>  	snpcr = I915_READ(GEN6_MBCUNIT_SNPCR);
>  	mutex_unlock(&dev_priv->dev->struct_mutex);
> @@ -1857,6 +1880,9 @@ i915_cache_sharing_write(struct file *filp,
>  	u32 snpcr;
>  	int val = 1;
>  
> +	if (!(IS_GEN6(dev) || IS_GEN7(dev)))
> +		return -ENODEV;
> +
>  	if (cnt > 0) {
>  		if (cnt > sizeof(buf) - 1)
>  			return -EINVAL;
> @@ -2061,6 +2087,7 @@ int i915_debugfs_init(struct drm_minor *minor)
>  				  &i915_cache_sharing_fops);
>  	if (ret)
>  		return ret;
> +
>  	ret = i915_debugfs_create(minor->debugfs_root, minor,
>  				  "i915_ring_stop",
>  				  &i915_ring_stop_fops);
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 21a0088..d5af41b 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -2272,6 +2272,8 @@ void gen6_set_rps(struct drm_device *dev, u8 val)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	u32 limits;
>  
> +	WARN_ON(!mutex_is_locked(&dev->struct_mutex));
> +
>  	limits = 0;
>  	if (val >= dev_priv->max_delay)
>  		val = dev_priv->max_delay;



-- 
Ben Widawsky, Intel Open Source Technology Center