On Thu, Jun 24, 2021 at 11:07:57AM +0200, Thomas Zimmermann wrote:

Hi

Am 24.06.21 um 10:51 schrieb Jani Nikula:

quoted

On Thu, 24 Jun 2021, Thomas Zimmermann [off-list ref] wrote:

quoted

Hi

Am 24.06.21 um 10:06 schrieb Jani Nikula:

quoted

On Thu, 24 Jun 2021, Thomas Zimmermann [off-list ref] wrote:

quoted

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 3417e1ac7918..10fe16bafcb6 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c

@@ -1748,8 +1748,16 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
   	unsigned int pipe_index;
   	unsigned int flags, pipe, high_pipe;
-	if (!dev->irq_enabled)
-		return -EOPNOTSUPP;
+#if defined(CONFIG_DRM_LEGACY)
+	if  (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY))) {
+		if (!dev->irq_enabled)
+			return -EOPNOTSUPP;
+	} else /* if DRIVER_MODESET */
+#endif
+	{
+		if (!drm_dev_has_vblank(dev))
+			return -EOPNOTSUPP;
+	}

Sheesh I hate this kind of inline #ifdefs.

Two alternate suggestions that I believe should be as just efficient:

Or how about:

static bool drm_wait_vblank_supported(struct drm_device *dev)

{

if defined(CONFIG_DRM_LEGACY)
	if  (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY)))

		return dev->irq_enabled;

#endif
	return drm_dev_has_vblank(dev);

}


?

It's inline, but still readable.

It's definitely better than the original, but it's unclear to me why
you'd prefer this over option 2) below. I guess the only reason I can
think of is emphasizing the conditional compilation. However,
IS_ENABLED() is widely used in this manner specifically to avoid inline
#if, and the compiler optimizes it away.

It's simply more readable to me as the condition is simpler. But option 2 is
also ok.

Either option looks good to me.

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Thanks for doing that!
Liviu

Best regards
Thomas

quoted

BR,
Jani.

quoted

Best regards
Thomas

quoted

1) The more verbose:

#if defined(CONFIG_DRM_LEGACY)
static bool drm_wait_vblank_supported(struct drm_device *dev)
{
	if  (unlikely(drm_core_check_feature(dev, DRIVER_LEGACY)))
		return dev->irq_enabled;
	else
		return drm_dev_has_vblank(dev);
}
#else
static bool drm_wait_vblank_supported(struct drm_device *dev)
{
	return drm_dev_has_vblank(dev);
}
#endif

2) The more compact:

static bool drm_wait_vblank_supported(struct drm_device *dev)
{
	if  (IS_ENABLED(CONFIG_DRM_LEGACY) && unlikely(drm_core_check_feature(dev, DRIVER_LEGACY)))
		return dev->irq_enabled;
	else
		return drm_dev_has_vblank(dev);
}

Then, in drm_wait_vblank_ioctl().

	if (!drm_wait_vblank_supported(dev))
		return -EOPNOTSUPP;

The compiler should do the right thing without any explicit inline
keywords etc.

BR,
Jani.

quoted

   	if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
   		return -EINVAL;

@@ -2023,7 +2031,7 @@ int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data,
   	if (!drm_core_check_feature(dev, DRIVER_MODESET))
   		return -EOPNOTSUPP;
-	if (!dev->irq_enabled)
+	if (!drm_dev_has_vblank(dev))
   		return -EOPNOTSUPP;
   	crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id);

@@ -2082,7 +2090,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
   	if (!drm_core_check_feature(dev, DRIVER_MODESET))
   		return -EOPNOTSUPP;
-	if (!dev->irq_enabled)
+	if (!drm_dev_has_vblank(dev))
   		return -EOPNOTSUPP;
   	crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id);

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

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