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From:   Abhishek Kumar <kuabhs@chromium.org>
Date:   Tue, 22 Dec 2020 14:36:58 -0800
Message-ID: <CACTWRwsM_RJnssBpxDpRSbex4_1T9QDv3+ZT7eLnYsgOgtGFQw@mail.gmail.com>
Subject: Re: [PATCH 3/3] ath10k: Set wiphy flag to trigger sta disconnect on
 hardware restart
To:     Youghandhar Chintala <youghand@codeaurora.org>
Cc:     ath10k <ath10k@lists.infradead.org>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        Brian Norris <briannorris@chromium.org>,
        Rakesh Pillai <pillair@codeaurora.org>
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On Tue, Dec 15, 2020 at 9:24 AM Youghandhar Chintala
<youghand@codeaurora.org> wrote:
>
> From: Rakesh Pillai <pillair@codeaurora.org>
>
> Currently after the hardware restart triggered from the driver,
> the station interface connection remains intact, since a disconnect
> trigger is not sent to userspace. This can lead to a problem in
> hardwares where the wifi mac sequence is added by the firmware.
>
> After the firmware restart, during subsytem recovery, the firmware
> restarts its wifi mac sequence number. Hence AP to which our device
> is connected will receive frames with a  wifi mac sequence number jump
> to the past, thereby resulting in the AP dropping all these frames,
> until the frame arrives with a wifi mac sequence number which AP was
> expecting.
>
> To avoid such frame drops, its better to trigger a station disconnect
> upon the  hardware restart. Indicate this support via a WIPHY flag
> to mac80211, if the hardware params flag mentions the support to
> add wifi mac sequence numbers for TX frames in the firmware.
>
> All the other hardwares, except WCN3990, are not affected by this
> change, since the hardware params flag is not set for any hardware
> except for WCN3990
>
> Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.1-01040-QCAHLSWMTPLZ-1
> Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1
> Tested-on: QCA6174 hw3.2 SDIO WLAN.RMH.4.4.1-00048
>
> Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
> Signed-off-by: Youghandhar Chintala <youghand@codeaurora.org>
> ---
>  drivers/net/wireless/ath/ath10k/core.c | 15 +++++++++++++++
>  drivers/net/wireless/ath/ath10k/hw.h   |  3 +++
>  drivers/net/wireless/ath/ath10k/mac.c  |  3 +++
>  3 files changed, 21 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
> index 796107b..4155f94 100644
> --- a/drivers/net/wireless/ath/ath10k/core.c
> +++ b/drivers/net/wireless/ath/ath10k/core.c
> @@ -90,6 +90,7 @@ static const struct ath10k_hw_params ath10k_hw_params_list[] = {
>                 .hw_filter_reset_required = true,
>                 .fw_diag_ce_download = false,
>                 .tx_stats_over_pktlog = true,
> +               .tx_mac_seq_by_fw = false,
Probably orthogonal to this patch, there is a static array maintained
for different hardware configs and the structure members like
"tx_mac_seq_by_fw" are initialized. This does not seem to be scalable
and probably these parameters can be auto populated based on FW
capabilities and so we don't have to maintain the static array.
Thoughts?

-Abhishek