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

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Date:   Wed, 5 Apr 2023 00:00:23 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Rob Clark <robdclark@...il.com>, dri-devel@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/vblank: Simplify drm_dev_has_vblank()

On Tue, Apr 04, 2023 at 10:46:00PM +0200, Daniel Vetter 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.
> 
> If you want to fix this, then I think the right fix is to rename num_crtcs
> to be something like num_vblank_crtcs. It's a historical accident back
> when vblanks without kms was a thing.
> 
> Plan B is someone gets really busy and fixes up the entire vblank mess and
> moves it into drm_crtc struct. Now that the dri1 drivers are gone we could
> indeed do that.

And easy first step could to simply wrap all the naked
&dev->vblank[drm_crtc_index()] things into a function
call with some cocci/etc. That way most of the vblank
code doesn't need to care where that thing actually lives.

-- 
Ville Syrjälä
Intel