[Mesa-dev] [PATCH 27/34] i965: Make CCS stride match kernel's expectations

[Ben Widawsky]

On 17-01-31 13:24:55, Jason Ekstrand wrote:
>On Mon, Jan 23, 2017 at 10:21 PM, Ben Widawsky <ben at bwidawsk.net> wrote:
>
>> v2: Put the commit message as a comment (Topi)
>>
>> Cc: Topi Pohjolainen <topi.pohjolainen at gmail.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Cc: Jason Ekstrand <jason at jlekstrand.net>
>> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
>> Acked-by: Daniel Stone <daniels at collabora.com>
>> ---
>>  src/mesa/drivers/dri/i965/intel_screen.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/intel_screen.c
>> b/src/mesa/drivers/dri/i965/intel_screen.c
>> index 85070bb54d..12b3b071e4 100644
>> --- a/src/mesa/drivers/dri/i965/intel_screen.c
>> +++ b/src/mesa/drivers/dri/i965/intel_screen.c
>> @@ -1023,7 +1023,10 @@ intel_from_planar(__DRIimage *parent, int plane,
>> void *loaderPrivate)
>>      if (parent == NULL || parent->planar_format == NULL) {
>>         if (is_aux) {
>>            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 / 64, 128);
>>
>
>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.
>
>--Jason
>
>

This formula doesn't match the kernel's expectations (unless Ville has updated
patches somewhere).

If you want I can do:
stride = ALIGN(parent->pitch, 4096) / 128;

>>            height = ALIGN(DIV_ROUND_UP(parent->height, 16), 32);
>>            dri_format = parent->dri_format;
>>            goto done;