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From: Jani Nikula <jani.nikula@linux.intel.com>
To: Thomas Zimmermann <tzimmermann@suse.de>,
	daniel@ffwll.ch, airlied@linux.ie, alexander.deucher@amd.com,
	christian.koenig@amd.com, Xinhui.Pan@amd.com,
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Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
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	intel-gfx@lists.freedesktop.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls
Date: Thu, 24 Jun 2021 11:06:19 +0300	[thread overview]
Message-ID: <87im23u1ok.fsf@intel.com> (raw)
In-Reply-To: <20210624072916.27703-5-tzimmermann@suse.de>

On Thu, 24 Jun 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
> For KMS drivers, replace the IRQ check in VBLANK ioctls with a check for
> vblank support. IRQs might be enabled wthout vblanking being supported.
>
> This change also removes the DRM framework's only dependency on IRQ state
> for non-legacy drivers. For legacy drivers with userspace modesetting,
> the original test remains in drm_wait_vblank_ioctl().
>
> v3:
> 	* optimize test in drm_wait_vblank_ioctl() for KMS case (Liviu)
> 	* update docs for drm_irq_uninstall()
> v2:
> 	* keep the old test for legacy drivers in
> 	  drm_wait_vblank_ioctl() (Daniel)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/drm_irq.c    | 13 ++++---------
>  drivers/gpu/drm/drm_vblank.c | 16 ++++++++++++----
>  2 files changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index c3bd664ea733..945dd82e2ea3 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -74,10 +74,8 @@
>   * only supports devices with a single interrupt on the main device stored in
>   * &drm_device.dev and set as the device paramter in drm_dev_alloc().
>   *
> - * These IRQ helpers are strictly optional. Drivers which roll their own only
> - * need to set &drm_device.irq_enabled to signal the DRM core that vblank
> - * interrupts are working. Since these helpers don't automatically clean up the
> - * requested interrupt like e.g. devm_request_irq() they're not really
> + * These IRQ helpers are strictly optional. Since these helpers don't automatically
> + * clean up the requested interrupt like e.g. devm_request_irq() they're not really
>   * recommended.
>   */
>  
> @@ -91,9 +89,7 @@
>   * and after the installation.
>   *
>   * This is the simplified helper interface provided for drivers with no special
> - * needs. Drivers which need to install interrupt handlers for multiple
> - * interrupts must instead set &drm_device.irq_enabled to signal the DRM core
> - * that vblank interrupts are available.
> + * needs.
>   *
>   * @irq must match the interrupt number that would be passed to request_irq(),
>   * if called directly instead of using this helper function.
> @@ -156,8 +152,7 @@ EXPORT_SYMBOL(drm_irq_install);
>   *
>   * Calls the driver's &drm_driver.irq_uninstall function and unregisters the IRQ
>   * handler.  This should only be called by drivers which used drm_irq_install()
> - * to set up their interrupt handler. Other drivers must only reset
> - * &drm_device.irq_enabled to false.
> + * to set up their interrupt handler.
>   *
>   * Note that for kernel modesetting drivers it is a bug if this function fails.
>   * The sanity checks are only to catch buggy user modesetting drivers which call
> 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:

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.

>  
>  	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);

-- 
Jani Nikula, Intel Open Source Graphics Center

  reply	other threads:[~2021-06-24  8:06 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-24  7:28 [PATCH v3 00/27] Deprecate struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 01/27] drm/amdgpu: Track IRQ state in local device state Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 02/27] drm/hibmc: Call drm_irq_uninstall() unconditionally Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 03/27] drm/radeon: Track IRQ state in local device state Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls Thomas Zimmermann
2021-06-24  8:06   ` Jani Nikula [this message]
2021-06-24  8:19     ` Thomas Zimmermann
2021-06-24  8:28     ` Thomas Zimmermann
2021-06-24  8:51       ` Jani Nikula
2021-06-24  9:07         ` Thomas Zimmermann
2021-06-24 10:27           ` Liviu Dudau
2021-06-24 12:03           ` Thierry Reding
2021-06-24 12:36             ` Jani Nikula
2021-06-24 12:57               ` Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 05/27] drm/armada: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 06/27] drm/i915: Track IRQ state in local device state Thomas Zimmermann
2021-06-24  8:08   ` Jani Nikula
2021-06-24  7:28 ` [PATCH v3 07/27] drm/komeda: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 08/27] drm/malidp: " Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 09/27] drm/exynos: " Thomas Zimmermann
2021-06-24  7:28 ` [PATCH v3 10/27] drm/kirin: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 11/27] drm/imx: " Thomas Zimmermann
2021-06-24  8:25   ` Philipp Zabel
2021-06-24  7:29 ` [PATCH v3 12/27] drm/imx/dcss: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 13/27] drm/mediatek: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 14/27] drm/nouveau: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 15/27] drm/omapdrm: Track IRQ state in local device state Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 16/27] drm/rcar-du: Don't set struct drm_device.irq_enabled Thomas Zimmermann
2021-06-24 10:47   ` Laurent Pinchart
2021-06-24  7:29 ` [PATCH v3 17/27] drm/rockchip: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 18/27] drm/sti: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 19/27] drm/stm: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 20/27] drm/sun4i: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 21/27] drm/tegra: " Thomas Zimmermann
2021-06-24 12:04   ` Thierry Reding
2021-06-24  7:29 ` [PATCH v3 22/27] drm/tidss: Don't use " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 23/27] drm/vc4: Don't set " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 24/27] drm/vkms: " Thomas Zimmermann
2021-06-24 10:48   ` Laurent Pinchart
2021-06-24  7:29 ` [PATCH v3 25/27] drm/vmwgfx: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 26/27] drm/xlnx: " Thomas Zimmermann
2021-06-24  7:29 ` [PATCH v3 27/27] drm/zte: " Thomas Zimmermann

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