linux-kernel - Re: [PATCH] drm/vblank: Simplify drm_dev_has

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Message-ID: <ef2ba536-a7ea-7cfb-7cf6-9e0c02aeba80@infradead.org>
Date:   Mon, 3 Apr 2023 09:28:25 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/vblank: Simplify drm_dev_has_vblank()



On 4/3/23 09:23, Ville Syrjälä wrote:
> On Mon, Apr 03, 2023 at 09:07:35AM -0700, Rob Clark wrote:
>> From: Rob Clark <robdclark@...omium.org>
>>
>> What does vblank have to do with num_crtcs?  Well, this was technically
>> correct, but you'd have to go look at where num_crtcs is initialized to
>> understand why.  Lets just replace it with the simpler and more obvious
>> check.
>>
>> Signed-off-by: Rob Clark <robdclark@...omium.org>
>> ---
>>  drivers/gpu/drm/drm_vblank.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
>> index 877e2067534f..ad34c235d853 100644
>> --- a/drivers/gpu/drm/drm_vblank.c
>> +++ b/drivers/gpu/drm/drm_vblank.c
>> @@ -575,7 +575,7 @@ EXPORT_SYMBOL(drm_vblank_init);
>>   */
>>  bool drm_dev_has_vblank(const struct drm_device *dev)
>>  {
>> -	return dev->num_crtcs != 0;
>> +	return !!dev->vblank;
> 
> The compiler knows how to turn things into a boolean.
>> Or I guess if we want to be a bit more explicit we could
> write this as
>  return dev->vblank != NULL;
> but IIRC that will make checkpatch complain because of
> someone's personal taste.

checkpatch isn't an absolute thing. :)

-- 
~Randy