linux-kernel - [PATCH 2/2] simplefb: use write-combined remapping

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Message-Id: <1380725919-1961-2-git-send-email-dh.herrmann@gmail.com>
Date:	Wed,  2 Oct 2013 16:58:39 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	linux-fbdev@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Tom Gundersen <teg@...m.no>,
	Alexandre Courbot <acourbot@...dia.com>,
	Stephen Warren <swarren@...dotorg.org>,
	dri-devel@...ts.freedesktop.org,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	David Herrmann <dh.herrmann@...il.com>
Subject: [PATCH 2/2] simplefb: use write-combined remapping

Framebuffers shouldn't be cached and it is usually very uncommon to read
them. Therefore, use ioremap_wc() to get significant speed improvements on
systems which provide it. On all other systems it's aliased to
ioremap_nocache() which is also fine.

Reported-by: Tom Gundersen <teg@...m.no>
Signed-off-by: David Herrmann <dh.herrmann@...il.com>
Tested-by: Tom Gundersen <teg@...m.no>
Tested-by: Alexandre Courbot <acourbot@...dia.com>
Tested-by: Stephen Warren <swarren@...dotorg.org>
---
 drivers/video/simplefb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/simplefb.c b/drivers/video/simplefb.c
index 74b016c..64db54a 100644
--- a/drivers/video/simplefb.c
+++ b/drivers/video/simplefb.c
@@ -219,8 +219,8 @@ static int simplefb_probe(struct platform_device *pdev)
 
 	info->fbops = &simplefb_ops;
 	info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE;
-	info->screen_base = ioremap(info->fix.smem_start,
-				    info->fix.smem_len);
+	info->screen_base = ioremap_wc(info->fix.smem_start,
+				       info->fix.smem_len);
 	if (!info->screen_base) {
 		framebuffer_release(info);
 		return -ENODEV;
-- 
1.8.4

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