linux-kernel - Re: [PATCH] drm/amd/display: Simplify same effect if/else blocks

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Date:   Mon, 23 Jan 2023 00:23:19 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Joe Perches <joe@...ches.com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Aurabindo Pillai <aurabindo.pillai@....com>
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Saurabh Singh Sengar <ssengar@...rosoft.com>,
        Praveen Kumar <kumarpraveen@...ux.microsoft.com>
Subject: Re: [PATCH] drm/amd/display: Simplify same effect if/else blocks

On Sun, Jan 15, 2023 at 12:52:10PM -0800, Joe Perches wrote:
> On Sun, 2023-01-15 at 15:30 +0530, Deepak R Varma wrote:
> > The if / else block code has same effect irrespective of the logical
> > evaluation.  Hence, simply the implementation by removing the unnecessary
> > conditional evaluation. While at it, also fix the long line checkpatch
> > complaint. Issue identified using cond_no_effect.cocci Coccinelle
> > semantic patch script.
> > 
> > Signed-off-by: Deepak R Varma <drv@...lo.com>
> > ---
> > Please note: The proposed change is compile tested only. If there are any
> > inbuilt test cases that I should run for further verification, I will appreciate
> > guidance about it. Thank you.
> 
> Preface: I do not know the code.
> 
> Perhaps Rodrigo Siqueira made a copy/paste error submitting the code for
> commit 9114b55fabae ("drm/amd/display: Fix SubVP control flow in the MPO context")
> as the code prior to this change is identical.
> 
> Perhaps one of the false uses should be true or dependent on the
> interdependent_update_lock state.

Thank you Joe for the recommendation.

Hi Rodrigo,
Can you review and comment on if and what is wrong with your commit?

Thank you,
./drv

> 
> > diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> []
> > @@ -3470,14 +3470,9 @@ static void commit_planes_for_stream(struct dc *dc,
> >  		/* Since phantom pipe programming is moved to post_unlock_program_front_end,
> >  		 * move the SubVP lock to after the phantom pipes have been setup
> >  		 */
> > -		if (should_lock_all_pipes && dc->hwss.interdependent_update_lock) {
> > -			if (dc->hwss.subvp_pipe_control_lock)
> > -				dc->hwss.subvp_pipe_control_lock(dc, context, false, should_lock_all_pipes, NULL, subvp_prev_use);
> > -		} else {
> > -			if (dc->hwss.subvp_pipe_control_lock)
> > -				dc->hwss.subvp_pipe_control_lock(dc, context, false, should_lock_all_pipes, NULL, subvp_prev_use);
> > -		}
> > -
> 
> Perhaps something like:
> 
> 		if (dc->hwss.subvp_pipe_control_lock)
> 			dc->hwss.subvp_pipe_control_lock(dc, context,
> 							 should_lock_all_pipes &&
> 							 dc->hwss.interdependent_update_lock,
> 							 should_lock_all_pipes, NULL, subvp_prev_use);
> 
> > +		if (dc->hwss.subvp_pipe_control_lock)
> > +			dc->hwss.subvp_pipe_control_lock(dc, context, false, should_lock_all_pipes,
> > +							 NULL, subvp_prev_use);
> >  		return;
> >  	}
> >  
>