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 5.14-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-5.14 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 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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/marvell/mwifiex/pcie.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/net/wireless/marvell/mwifiex/pcie.c +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c @@ -1479,6 +1479,14 @@ 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-5.14/mwifiex-try-waking-the-firmware-until-we-get-an-interrupt.patch queue-5.14/mwifiex-read-a-pci-register-after-writing-the-tx-ring-write-pointer.patch