[PATCH 4/5] gxt4500: Use write-combining for framebuffer

Ondrej Zary
2015-07-26T21:26:57Z

Use write-combining for framebuffer to greatly improve performance on x86.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
---
drivers/video/fbdev/gxt4500.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/gxt4500.c b/drivers/video/fbdev/gxt4500.c
index 442b07c..e0d1550 100644
--- a/drivers/video/fbdev/gxt4500.c
+++ b/drivers/video/fbdev/gxt4500.c
@@ -142,7 +142,7 @@ static const unsigned char watfmt[] = {

struct gxt4500_par {
void __iomem *regs;
-
+ int wc_cookie;
int pixfmt; /* pixel format, see DFA_PIX_* values */

/* PLL parameters */
@@ -663,7 +663,7 @@ 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 = ioremap_wc(fb_phys, info->fix.smem_len);
if (!info->screen_base) {
dev_err(&pdev->dev, "gxt4500: cannot map framebuffer\n");
goto err_unmap_regs;
@@ -671,6 +671,9 @@ static int gxt4500_probe(struct pci_dev *pdev, const struct pci_device_id *ent)

pci_set_drvdata(pdev, info);

+ par->wc_cookie = arch_phys_wc_add(info->fix.smem_start,
+ info->fix.smem_len);
+
#ifdef __BIG_ENDIAN
/* Set byte-swapping for DFA aperture for all pixel sizes */
pci_write_config_dword(pdev, CFG_ENDIAN0, 0x333300);
@@ -735,6 +738,7 @@ static void gxt4500_remove(struct pci_dev *pdev)
return;
par = info->par;
unregister_framebuffer(info);
+ arch_phys_wc_del(par->wc_cookie);
fb_dealloc_cmap(&info->cmap);
iounmap(par->regs);
iounmap(info->screen_base);
--
Ondrej Zary