drm/msm: Make sure that WPTR stays in bounds

Currently the value written to CP_RB_WPTR is calculated on the fly as
(rb->next - rb->start). But as the code is designed rb->next is wrapped
before writing the commands so if a series of commands happened to
fit perfectly in the ringbuffer, rb->next would end up being equal to
rb->size / 4 and thus result in an out of bounds address to CP_RB_WPTR.

The easiest way to fix this is to mask WPTR when writing it to the
hardware; it makes the hardware happy and the rest of the ringbuffer
math appears to work and there isn't any point in messing with things.

Change-Id: Ic0dedbade543a2253b88acf46a8f8e062ae7faf9
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>

0 files changed, 0 insertions, 0 deletions