gma500: Be smarter about layout

If we can't fit a page aligned display stride then it's not the end of the
world for a normal font, so try half a page and work down sizes.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 30 insertions, 16 deletions

diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
index 652f1ecb0a69..9ec167600d04 100644
--- a/drivers/gpu/drm/gma500/framebuffer.c
+++ b/drivers/gpu/drm/gma500/framebuffer.c
@@ -385,7 +385,8 @@ static int psbfb_create(struct psb_fbdev *fbdev,
         int ret;
         struct gtt_range *backing;
         u32 bpp, depth;
-        int gtt_roll = 1;
+        int gtt_roll = 0;
+        int pitch_lines = 0;
 
         mode_cmd.width = sizes->surface_width;
         mode_cmd.height = sizes->surface_height;
@@ -395,27 +396,40 @@ static int psbfb_create(struct psb_fbdev *fbdev,
         if (bpp == 24)
                 bpp = 32;
 
-        /* Acceleration via the GTT requires pitch to be 4096 byte aligned 
-           (ie 1024 or 2048 pixels in normal use) */
-        mode_cmd.pitches[0] =  ALIGN(mode_cmd.width * ((bpp + 7) / 8), 4096);
-        depth = sizes->surface_depth;
+        do {
+                /*
+                 * Acceleration via the GTT requires pitch to be
+                 * power of two aligned. Preferably page but less
+                 * is ok with some fonts
+                 */
+                mode_cmd.pitches[0] =  ALIGN(mode_cmd.width * ((bpp + 7) / 8), 4096 >> pitch_lines);
+                depth = sizes->surface_depth;
+
+                size = mode_cmd.pitches[0] * mode_cmd.height;
+                size = ALIGN(size, PAGE_SIZE);
+
+                /* Allocate the fb in the GTT with stolen page backing */
+                backing = psbfb_alloc(dev, size);
+
+                if (pitch_lines)
+                        pitch_lines *= 2;
+                else
+                        pitch_lines = 1;
+                gtt_roll++;
+        } while (backing == NULL && pitch_lines <= 16);
 
-        size = mode_cmd.pitches[0] * mode_cmd.height;
-        size = ALIGN(size, PAGE_SIZE);
+        /* The final pitch we accepted if we succeeded */
+        pitch_lines /= 2;
 
-        /* Try and allocate with the alignment we need */
-        backing = psbfb_alloc(dev, size);
         if (backing == NULL) {
                 /*
                  *      We couldn't get the space we wanted, fall back to the
                  *      display engine requirement instead.  The HW requires
                  *      the pitch to be 64 byte aligned
-                 *
-                 *      FIXME: We could try alignments in a loop so that we can still
-                 *      accelerate power of two font sizes.
                  */
 
                 gtt_roll = 0;   /* Don't use GTT accelerated scrolling */
+                pitch_lines = 64;
 
                 mode_cmd.pitches[0] =  ALIGN(mode_cmd.width * ((bpp + 7) / 8), 64);
 
@@ -452,12 +466,12 @@ static int psbfb_create(struct psb_fbdev *fbdev,
         strcpy(info->fix.id, "psbfb");
 
         info->flags = FBINFO_DEFAULT;
-        if (gtt_roll) { /* GTT rolling seems best */
+        if (dev_priv->ops->accel_2d && pitch_lines > 8) /* 2D engine */
+                info->fbops = &psbfb_ops;
+        else if (gtt_roll) {    /* GTT rolling seems best */
                 info->fbops = &psbfb_roll_ops;
                 info->flags |= FBINFO_HWACCEL_YPAN;
-        } else if (dev_priv->ops->accel_2d)     /* 2D engine */
-                info->fbops = &psbfb_ops;
-        else    /* Software */
+        } else  /* Software */
                 info->fbops = &psbfb_unaccel_ops;
 
         ret = fb_alloc_cmap(&info->cmap, 256, 0);