[PATCH 5.17 0577/1126] ath11k: Invalidate cached reo ring entry before accessing it

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 05:10:51 EST

From: Rameshkumar Sundaram <quic_ramess@xxxxxxxxxxx>

[ Upstream commit f2180ccb52b5fd0876291ad2df37e2898cac18cf ]

REO2SW ring descriptor is currently allocated in cacheable memory.
While reaping reo ring entries on second trial after updating head
pointer, first entry is not invalidated before accessing it.

This results in host reaping and using cached descriptor which is
already overwritten in memory by DMA device (HW).
Since the contents of descriptor(buffer id, peer info and other information
bits) are outdated host throws errors like below while parsing corresponding
MSDU's and drops them.

[347712.048904] ath11k_pci 0004:01:00.0: msdu_done bit in attention is not set
[349173.355503] ath11k_pci 0004:01:00.0: frame rx with invalid buf_id 962

Move the try_again: label above ath11k_hal_srng_access_begin()
so that first entry will be invalidated and prefetched.

Tested-on: QCN9074 hw1.0 PCI WLAN.HK.

Fixes: 6452f0a3d565 ("ath11k: allocate dst ring descriptors from cacheable memory")
Signed-off-by: Rameshkumar Sundaram <quic_ramess@xxxxxxxxxxx>
Signed-off-by: Kalle Valo <quic_kvalo@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/1645000354-32558-1-git-send-email-quic_ramess@xxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/wireless/ath/ath11k/dp_rx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index c212a789421e..e432f8dc05d6 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -2642,9 +2642,9 @@ int ath11k_dp_process_rx(struct ath11k_base *ab, int ring_id,


ath11k_hal_srng_access_begin(ab, srng);

while (likely(desc =
(struct hal_reo_dest_ring *)ath11k_hal_srng_dst_get_next_entry(ab,
srng))) {