This is a note to let you know that I've just added the patch titled
mwifiex: Read a PCI register after writing the TX ring write pointer
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mwifiex-read-a-pci-register-after-writing-the-tx-ring-write-pointer.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e5f4eb8223aa740237cd463246a7debcddf4eda1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20Dre=C3=9Fler?= <verdre@xxxxxxx>
Date: Mon, 11 Oct 2021 15:32:23 +0200
Subject: mwifiex: Read a PCI register after writing the TX ring write pointer
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From: Jonas Dreßler <verdre@xxxxxxx>
commit e5f4eb8223aa740237cd463246a7debcddf4eda1 upstream.
On the 88W8897 PCIe+USB card the firmware randomly crashes after setting
the TX ring write pointer. The issue is present in the latest firmware
version 15.68.19.p21 of the PCIe+USB card.
Those firmware crashes can be worked around by reading any PCI register
of the card after setting that register, so read the PCI_VENDOR_ID
register here. The reason this works is probably because we keep the bus
from entering an ASPM state for a bit longer, because that's what causes
the cards firmware to crash.
This fixes a bug where during RX/TX traffic and with ASPM L1 substates
enabled (the specific substates where the issue happens appear to be
platform dependent), the firmware crashes and eventually a command
timeout appears in the logs.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=109681
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jonas Dreßler <verdre@xxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211011133224.15561-2-verdre@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/wireless/mwifiex/pcie.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/drivers/net/wireless/mwifiex/pcie.c
+++ b/drivers/net/wireless/mwifiex/pcie.c
@@ -1210,6 +1210,14 @@ mwifiex_pcie_send_data(struct mwifiex_ad
ret = -1;
goto done_unmap;
}
+
+ /* The firmware (latest version 15.68.19.p21) of the 88W8897 PCIe+USB card
+ * seems to crash randomly after setting the TX ring write pointer when
+ * ASPM powersaving is enabled. A workaround seems to be keeping the bus
+ * busy by reading a random register afterwards.
+ */
+ mwifiex_read_reg(adapter, PCI_VENDOR_ID, &rx_val);
+
if ((mwifiex_pcie_txbd_not_full(card)) &&
tx_param->next_pkt_len) {
/* have more packets and TxBD still can hold more */
Patches currently in stable-queue which might be from verdre@xxxxxxx are
queue-4.4/mwifiex-read-a-pci-register-after-writing-the-tx-ring-write-pointer.patch
