Hi, On Thu, Jan 20, 2022 at 10:44 PM Youghandhar Chintala <quic_youghand@xxxxxxxxxxx> wrote: > > Currently for WCN3990, the host driver can send two wmi commands at once, > now it is limiting to one because if HOST wants to initiate 2 DMA transfers, > it is possible when copy complete interrupt for first DMA reaches HOST, > CE has already updated SRRI for both DMA transfers and is in the middle > of 2nd DMA. HOST uses SRRI to interpret how many DMA’s have been completed > and tries to unmap/free both the DMA entries, but CE is still in the middle > of 2nd DMA which can cause SMMU issues or corruption. > > We are seeing a corner case smmu fault issue where copy engine is still accessing > the memory though host unmaps it hence as work around we are delaying the > unmapping the memory and tx credit to one. > > Youghandhar Chintala (2): > ath10k: Set tx credit to one for wcn3990 snoc based devices > ath10k: Delay the unmapping of the buffer > > drivers/net/wireless/ath/ath10k/core.c | 30 ++++++++++++++++++++++++++ > drivers/net/wireless/ath/ath10k/htc.c | 18 +++++++++++++--- > drivers/net/wireless/ath/ath10k/htc.h | 1 + > drivers/net/wireless/ath/ath10k/hw.h | 6 ++++++ > 4 files changed, 52 insertions(+), 3 deletions(-) I don't understand the root cause here myself. I also don't have enough skin in the game to say whether this is the best/cleanest way to work around the problem. Thus I'll refrain from a Reviewed-by tag. That being said, I did a bunch of testing of this solution and I also am aware of others that have tested it. Thus I'm convinced that it at least works around the problem that has been observed. Hence: Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx> In my case I was on the same (or nearly the same) hardware as Youghandhar, though I had a slightly older build. FWIW: Tested-on: WLAN.HL.3.2.2.c10-00754-QCAHLSWMTPL-1 -Doug
