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wifi: brcmfmac: map msgbuf RX packet IDs bidirectional

PATCH In review Aditya Garg 3 participants 3 messages Oct 21

Subsystems (2)
PCI Broadcom BRCM80211 IEEE802.11 wireless drivers
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Aditya Garg

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#0 lore raw

PATCH 1/1 wifi: brcmfmac: map msgbuf RX packet IDs bidirectional

From: Jason Perlow <[email protected]>

Commit f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs") maps the RX packet ID buffers DMA_FROM_DEVICE. The BCM4364 firmware also reads posted RX buffers, so with VT-d translation enabled every such read faults ("PTE Read access is not set") and the firmware crashes and resets in a loop.

Map the RX pool DMA_BIDIRECTIONAL again, as before that commit. TX keeps DMA_TO_DEVICE.

Fixes f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs")
Cc [email protected]
Signed-off-by Jason Perlow <[email protected]>
Signed-off-by Aditya Garg <[email protected]>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c +1 -1
index 069ba70..ff47d48 100644
@@ -1639,7 +1639,7 @@ int brcmf_proto_msgbuf_attach(struct brcmf_pub *drvr)
 	if (!msgbuf->tx_pktids)
 		goto fail;
 	msgbuf->rx_pktids = brcmf_msgbuf_init_pktids(NR_RX_PKTIDS,
-						     DMA_FROM_DEVICE);
+						     DMA_BIDIRECTIONAL);
 	if (!msgbuf->rx_pktids)
 		goto fail;
Signature · 1 line
2.53.0
AI review
#1 lore raw
Sashiko has reviewed this patch and found no issues.
Quoted 8 lines

From: Jason Perlow <[email protected]>

Commit f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs") maps the RX packet ID buffers DMA_FROM_DEVICE. The BCM4364 firmware also reads posted RX buffers, so with VT-d translation enabled every such read faults ("PTE Read access is not set") and the firmware crashes and resets in a loop.

Quoted 7 lines

Map the RX pool DMA_BIDIRECTIONAL again, as before that commit. TX keeps DMA_TO_DEVICE.

Fixes f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs")
Cc [email protected]
Signed-off-by Jason Perlow <[email protected]>
Signed-off-by Aditya Garg <[email protected]>

Sashiko has reviewed this patch and found no issues.

Signature · 1 line
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1
maintainer Acked-by on v1 1/1
#2 lore raw
In reply to Aditya Garg

Op 21 oktober 2026 19:23:05 schreef Aditya Garg <[email protected]>:

Quoted 8 lines

From: Jason Perlow <[email protected]>

Commit f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs") maps the RX packet ID buffers DMA_FROM_DEVICE. The BCM4364 firmware also reads posted RX buffers, so with VT-d translation enabled every such read faults ("PTE Read access is not set") and the firmware crashes and resets in a loop.

Quoted 5 lines

Map the RX pool DMA_BIDIRECTIONAL again, as before that commit. TX keeps DMA_TO_DEVICE.

Fixes f0ba5fd51ff2 ("wifi: brcmfmac: Set DMA direction for msgbuf packet IDs")
Cc [email protected]
Acked-by Arend van Spriel <[email protected]>
Quoted 5 lines
Signed-off-by Jason Perlow <[email protected]>
Signed-off-by Aditya Garg <[email protected]>

---
drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)