[Xen-devel] [PATCH v1 17/47] video: fbdev: vesafb: only support MTRR_TYPE_WRCOMB

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>

No other video driver uses MTRR types except for MTRR_TYPE_WRCOMB,
the other MTRR types were implemented and supported here but with
no real good reason. The ioremap() APIs are architecture agnostic and
at least on x86 PAT is a new design that extends MTRRs and
can replace it in a much cleaner way, where so long as the
proper ioremap_wc() or variant API is used the right thing will
be done behind the scenes. This is the only driver left using the
other MTRR types -- and since there is no good reason for it now
rip them out.

Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: Antonino Daplas <adaplas@xxxxxxxxx>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Cc: linux-fbdev@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
---
 drivers/video/fbdev/vesafb.c | 62 ++++++++++++--------------------------------
 1 file changed, 16 insertions(+), 46 deletions(-)

diff --git a/drivers/video/fbdev/vesafb.c b/drivers/video/fbdev/vesafb.c
index d79a0ac..191156b 100644
--- a/drivers/video/fbdev/vesafb.c
+++ b/drivers/video/fbdev/vesafb.c
@@ -404,60 +404,30 @@ static int vesafb_probe(struct platform_device *dev)
         * region already (FIXME) */
        request_region(0x3c0, 32, "vesafb");
 
+       if (mtrr == 3) {
 #ifdef CONFIG_MTRR
-       if (mtrr) {
                unsigned int temp_size = size_total;
-               unsigned int type = 0;
+               int rc;
 
-               switch (mtrr) {
-               case 1:
-                       type = MTRR_TYPE_UNCACHABLE;
-                       break;
-               case 2:
-                       type = MTRR_TYPE_WRBACK;
-                       break;
-               case 3:
-                       type = MTRR_TYPE_WRCOMB;
-                       break;
-               case 4:
-                       type = MTRR_TYPE_WRTHROUGH;
-                       break;
-               default:
-                       type = 0;
-                       break;
-               }
-
-               if (type) {
-                       int rc;
-
-                       /* Find the largest power-of-two */
-                       temp_size = roundup_pow_of_two(temp_size);
+               /* Find the largest power-of-two */
+               temp_size = roundup_pow_of_two(temp_size);
 
-                       /* Try and find a power of two to add */
-                       do {
-                               rc = mtrr_add(vesafb_fix.smem_start, temp_size,
-                                             type, 1);
-                               temp_size >>= 1;
-                       } while (temp_size >= PAGE_SIZE && rc == -EINVAL);
-               }
-       }
+               /* Try and find a power of two to add */
+               do {
+                       rc = mtrr_add(vesafb_fix.smem_start, temp_size,
+                                     MTRR_TYPE_WRCOMB, 1);
+                       temp_size >>= 1;
+               } while (temp_size >= PAGE_SIZE && rc == -EINVAL);
 #endif
-       
-       switch (mtrr) {
-       case 1: /* uncachable */
-               info->screen_base = ioremap_nocache(vesafb_fix.smem_start, 
vesafb_fix.smem_len);
-               break;
-       case 2: /* write-back */
-               info->screen_base = ioremap_cache(vesafb_fix.smem_start, 
vesafb_fix.smem_len);
-               break;
-       case 3: /* write-combining */
                info->screen_base = ioremap_wc(vesafb_fix.smem_start, 
vesafb_fix.smem_len);
-               break;
-       case 4: /* write-through */
-       default:
+       } else {
+#ifdef CONFIG_MTRR
+               if (mtrr && mtrr != 3)
+                       WARN_ONCE(1, "Only MTRR_TYPE_WRCOMB (3) make sense\n");
+#endif
                info->screen_base = ioremap(vesafb_fix.smem_start, 
vesafb_fix.smem_len);
-               break;
        }
+
        if (!info->screen_base) {
                printk(KERN_ERR
                       "vesafb: abort, cannot ioremap video memory 0x%x @ 
0x%lx\n",
-- 
2.3.2.209.gd67f9d5.dirty


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