linux-kernel - [PATCH v1 44/47] video: fbdev: atmel_lcdfb: use ioremap

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Message-Id: <1426893517-2511-45-git-send-email-mcgrof@do-not-panic.com>
Date:	Fri, 20 Mar 2015 16:18:34 -0700
From:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>
To:	luto@...capital.net, mingo@...hat.com, tglx@...utronix.de,
	hpa@...or.com, jgross@...e.com, JBeulich@...e.com, bp@...e.de,
	suresh.b.siddha@...el.com, venkatesh.pallipadi@...el.com,
	airlied@...hat.com
Cc:	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
	x86@...nel.org, xen-devel@...ts.xenproject.org,
	"Luis R. Rodriguez" <mcgrof@...e.com>, Ingo Molnar <mingo@...e.hu>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Antonino Daplas <adaplas@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>
Subject: [PATCH v1 44/47] video: fbdev: atmel_lcdfb: use ioremap_wc() for framebuffer

From: "Luis R. Rodriguez" <mcgrof@...e.com>

The driver doesn't use mtrr_add() or arch_phys_wc_add() but
since we know the framebuffer is isolated already on an
ioremap() we can take advantage of write combining for
performance where possible.

In this case there are a few motivations for this:

a) Take advantage of PAT when available

b) Help with the goal of eventually using _PAGE_CACHE_UC over
   _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (de33c442e)

Cc: Suresh Siddha <suresh.b.siddha@...el.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Juergen Gross <jgross@...e.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Airlie <airlied@...hat.com>
Cc: Antonino Daplas <adaplas@...il.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@...com>
Cc: linux-fbdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@...e.com>
---
 drivers/video/fbdev/atmel_lcdfb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/atmel_lcdfb.c b/drivers/video/fbdev/atmel_lcdfb.c
index 94a8d04..abadc49 100644
--- a/drivers/video/fbdev/atmel_lcdfb.c
+++ b/drivers/video/fbdev/atmel_lcdfb.c
@@ -1266,7 +1266,8 @@ static int __init atmel_lcdfb_probe(struct platform_device *pdev)
 			goto stop_clk;
 		}
 
-		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) {
 			ret = -ENOMEM;
 			goto release_intmem;
-- 
2.3.2.209.gd67f9d5.dirty

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