linux-kernel - [PATCH v1] drm/kms/atomic: Improving func drm_atomic_plane

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Message-Id: <20180727110534epcas5p1b5d48f9f92b7d6874bbe15c2f80dce1c~FNQK6sJPs2704827048epcas5p1Q@epcas5p1.samsung.com>
Date:   Fri, 27 Jul 2018 16:34:05 +0530
From:   Satendra Singh Thakur <satendra.t@...sung.com>
To:     Gustavo Padovan <gustavo@...ovan.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     vineet.j@...sung.com, hemanshu.s@...sung.com, sst2005@...il.com,
        Satendra Singh Thakur <satendra.t@...sung.com>
Subject: [PATCH v1] drm/kms/atomic: Improving func drm_atomic_plane_check

Currently, in the func drm_atomic_plane_check;
there are 3 if statements in the beginning with total 5 conditions.
these conditions are
crtc is NULL but fb is non-NULL
if (state->crtc && !state->fb)
crtc is non-NULL but fb is NULL
if (state->fb && !state->crtc)
crtc is NULL (and fb is also NULL)
if (!state->crtc)

The same code can be re-written using 2 if statements and 4 conditions.
first we check whether crtc and fb both are NULL
if (!state->crtc && !state->fb)
then we check either crtc or fb is NULL
if (!state->crtc || !state->fb)

Signed-off-by: Satendra Singh Thakur <satendra.t@...sung.com>
---
 v1: Hi Mr Maarten, Thanks for the comments.
     I have splitted them into two patches.  
 
 drivers/gpu/drm/drm_atomic.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 895741e..0415bbf 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -912,18 +912,15 @@ static int drm_atomic_plane_check(struct drm_plane *plane,
 	unsigned int fb_width, fb_height;
 	int ret;
 
-	/* either *both* CRTC and FB must be set, or neither */
-	if (state->crtc && !state->fb) {
-		DRM_DEBUG_ATOMIC("CRTC set but no FB\n");
-		return -EINVAL;
-	} else if (state->fb && !state->crtc) {
-		DRM_DEBUG_ATOMIC("FB set but no CRTC\n");
-		return -EINVAL;
-	}
-
 	/* if disabled, we don't care about the rest of the state: */
-	if (!state->crtc)
+	if (!state->crtc && !state->fb)
 		return 0;
+	/* both CRTC and FB must be set*/
+	if (!state->crtc || !state->fb) {
+		DRM_DEBUG_ATOMIC("Either invalid CRTC [%p] or invalid FB [%p]\n",
+		state->crtc, state->fb);
+		return -EINVAL;
+	}
 
 	/* Check whether this plane is usable on this CRTC */
 	if (!(plane->possible_crtcs & drm_crtc_mask(state->crtc))) {
-- 
2.7.4