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From: Thomas Zimmermann <tzimmermann@suse.de>
To: Jani Nikula <jani.nikula@linux.intel.com>,
	daniel@ffwll.ch, airlied@linux.ie, alexander.deucher@amd.com,
	christian.koenig@amd.com, Xinhui.Pan@amd.com,
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Cc: linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-rockchip@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	amd-gfx@lists.freedesktop.org,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	linux-tegra@vger.kernel.org, linux-sunxi@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 04/27] drm: Don't test for IRQ support in VBLANK ioctls
Date: Thu, 24 Jun 2021 11:07:57 +0200	[thread overview]
Message-ID: <af21db75-584f-aec0-9659-d5386f27b4ea@suse.de> (raw)
In-Reply-To: <877dijtzl2.fsf@intel.com>


[-- Attachment #1.1: Type: text/plain, Size: 4052 bytes --]

Hi

Am 24.06.21 um 10:51 schrieb Jani Nikula:
> On Thu, 24 Jun 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Hi
>>
>> Am 24.06.21 um 10:06 schrieb Jani Nikula:
>>> On Thu, 24 Jun 2021, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>> 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.

Best regards
Thomas

> 
> BR,
> Jani.
> 
> 
>>
>> Best regards
>> Thomas
>>
>>>
>>> 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);
>>>
> 

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


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  reply	other threads:[~2021-06-24  9:08 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
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 [this message]
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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