[PATCH v1 46/47] video: fbdev: gxt4500: use pci_ioremap_wc_bar() for framebuffer

Luis R. Rodriguez
2015-03-21T01:02:15Z

From: "Luis R. Rodriguez" <mcgrof@suse.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@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: linux-fbdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
---
drivers/video/fbdev/gxt4500.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/gxt4500.c b/drivers/video/fbdev/gxt4500.c
index 135d78a..f19133a 100644
--- a/drivers/video/fbdev/gxt4500.c
+++ b/drivers/video/fbdev/gxt4500.c
@@ -662,7 +662,7 @@ static int gxt4500_probe(struct pci_dev *pdev, const struct pci_device_id *ent)

info->fix.smem_start = fb_phys;
info->fix.smem_len = pci_resource_len(pdev, 1);
- info->screen_base = pci_ioremap_bar(pdev, 1);
+ info->screen_base = pci_ioremap_wc_bar(pdev, 1);
if (!info->screen_base) {
dev_err(&pdev->dev, "gxt4500: cannot map framebuffer\n");
goto err_unmap_regs;
--
2.3.2.209.gd67f9d5.dirty