From: "Luis R. Rodriguez" <[email protected]> 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() (see commit de33c442e titled "x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range()") Cc: Laurent Pinchart <[email protected]> Cc: Rob Clark <[email protected]> Cc: Geert Uytterhoeven <[email protected]> Cc: Suresh Siddha <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Dave Airlie <[email protected]> Cc: Antonino Daplas <[email protected]> Cc: Jean-Christophe Plagniol-Villard <[email protected]> Cc: Tomi Valkeinen <[email protected]> Cc: [email protected] Cc: [email protected] Acked-by: Tomi Valkeinen <[email protected]> Signed-off-by: Luis R. Rodriguez <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in Please read the FAQ at http://www.tux.org/lkml/
