linux-kernel - [PATCH] drm/kms/crtc: Saving crtc->primary into a drm_plane pointer instead of dereferencing it every time.

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Message-Id: <20180730060607epcas5p18565ae86e1c88e82469554aa3c0e1664~GEGlfPEp_2913429134epcas5p1v@epcas5p1.samsung.com>
Date:   Mon, 30 Jul 2018 11:35:58 +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,
        nishant.y08@...sung.com, sst2005@...il.com,
        Satendra Singh Thakur <satendra.t@...sung.com>
Subject: [PATCH] drm/kms/crtc: Saving crtc->primary into a drm_plane pointer
 instead of dereferencing it every time.

In the func __drm_mode_set_config_internal,
objects (fb, old_fb, crtc) of crtc->primary are used at many places.
To access the objects of primary, it is dereferenced from crtc every
time. It's better to save it into drm_plane pointer.
This will make the code look simple.

Signed-off-by: Satendra Singh Thakur <satendra.t@...sung.com>
---
 drivers/gpu/drm/drm_crtc.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 98a36e6..9644f5b 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -462,6 +462,7 @@ static int __drm_mode_set_config_internal(struct drm_mode_set *set,
 	struct drm_crtc *crtc = set->crtc;
 	struct drm_framebuffer *fb;
 	struct drm_crtc *tmp;
+	struct drm_plane *plane;
 	int ret;
 
 	/*
@@ -469,23 +470,27 @@ static int __drm_mode_set_config_internal(struct drm_mode_set *set,
 	 * connectors from it), hence we need to refcount the fbs across all
 	 * crtcs. Atomic modeset will have saner semantics ...
 	 */
-	drm_for_each_crtc(tmp, crtc->dev)
-		tmp->primary->old_fb = tmp->primary->fb;
+	drm_for_each_crtc(tmp, crtc->dev) {
+		plane = tmp->primary;
+		plane->old_fb = plane->fb;
+	}
 
 	fb = set->fb;
-
 	ret = crtc->funcs->set_config(set, ctx);
 	if (ret == 0) {
-		crtc->primary->crtc = fb ? crtc : NULL;
-		crtc->primary->fb = fb;
+		plane = crtc->primary;
+		plane->crtc = fb ? crtc : NULL;
+		plane->fb = fb;
 	}
 
 	drm_for_each_crtc(tmp, crtc->dev) {
-		if (tmp->primary->fb)
-			drm_framebuffer_get(tmp->primary->fb);
-		if (tmp->primary->old_fb)
-			drm_framebuffer_put(tmp->primary->old_fb);
-		tmp->primary->old_fb = NULL;
+		plane = tmp->primary;
+		if (plane->fb)
+			drm_framebuffer_get(plane->fb);
+		if (plane->old_fb) {
+			drm_framebuffer_put(plane->old_fb);
+			plane->old_fb = NULL;
+		}
 	}
 
 	return ret;
-- 
2.7.4