gpu: nvgpu: reset patch_ctx.data_count

Patch buffer can hold 128 u32 entries. Each patch write
takes total of 2 u32 entries,  1 u32 for addr and 1 u32
for data. Ideally 64 entries could be written before buffer
overflows. Driver patch some things when creating the channel,
and later when context switch type is changed after channel is loaded.

Reset patch_ctx.data_count before beginning patch
write otherwise system might not be in a state to accept all
patch writes even if patch buffer has valid entries.
If the patch buffer has non-zero entries, then the patch buffer
would be read and all pri writes would be sent out. Once done,
ucode updates the main header patch buffer count to 0.

Without this fix, below priv errors seen on t186 platforms
SYS Write error for ADR 0, INFO 0d000200 and CODE badf1100
Error info decodes as:
  NV_PPRIV_SYS_PRIV_ERROR_INFO    R[0x00122128]
    SUBID                                    [29:24]  13 (?)
    LOCAL_ORDERING                           [22:22]   0 (I)
    PRIV_LEVEL                               [21:20]   0 (I)
    SENDING_RS                               [17:12]   0 (I)
    PENDING                                  [ 9: 9]   1 (?)
    ORPHAN                                   [ 8: 8]   0 (I)
    PRIV_MASTER                              [ 5: 0]   0 (I)

Ctxsw ucode(subid 13 i.e. 0xd) makes only few pri transactions
at priv level 0. Patch buffer pri writes are one of those.

Bug 200350539

Change-Id: If9e71b5fef4d85600d72a8a633a082d9261c3e1b
Signed-off-by: Seema Khowala <seemaj@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1581591
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

0 files changed, 0 insertions, 0 deletions