i965: Make CCS stride match kernel's expectations

v2: Put the commit message as a comment (Topi)

v3: Use different stride calculation. (Jason)
Quoting Jason's review feedback:
"Does the kernel expect the alignment to be 128 or 64?  Given that ville
likes 64-wide tiles, I think it should be 64.  Really, I think the more
accurate calculation would be

stride = ALIGN(parent->pitch, 4096) / 64;

4096 is the stride in bytes in the primary surface required to cross a
single CCS tile. The calculation you have above will work in the sense
that the worst that happens is for it to align up a bit too far.  In any
case, what matters is that we a) have enough space and b) exactly match the
kernel's calculation."

The above doesn't actually work. The kernel seems to want a divisor of
128.

Cc: Topi Pohjolainen <topi.pohjolainen@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Acked-by: Daniel Stone <daniels@collabora.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 8bd179338e..746c6c938e 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -968,7 +968,10 @@ intel_from_planar(__DRIimage *parent, int plane, void *loaderPrivate)
           height = ALIGN(DIV_ROUND_UP(parent->height, 16), 64);
           dri_format = parent->dri_format;
           offset = parent->aux_offset;
-          stride = ALIGN(parent->pitch / 32, 128);
+          /* Make CCS stride match kernel's expectations. Mesa's internals
+           * expect: stride = ALIGN(parent->pitch / 32, 128)
+           */
+          stride = ALIGN(parent->pitch / 4096, 128);
        } else {
           return NULL;
        }