linux-kernel - Re: [PATCH 1/3] mwifiex: disable ps_mode explicitly by default instead

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Date:   Thu, 29 Oct 2020 11:25:54 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Tsuchiya Yuto <kitakar@...il.com>
Cc:     Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi.bhat@....com>,
        Xinming Hu <huxinming820@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...el.com>, verdre@...d.nl
Subject: Re: [PATCH 1/3] mwifiex: disable ps_mode explicitly by default instead

On Wed, Oct 28, 2020 at 7:04 PM Tsuchiya Yuto <kitakar@...il.com> wrote:
>
> On Microsoft Surface devices (PCIe-88W8897), the ps_mode causes
> connection unstable, especially with 5GHz APs. Then, it eventually causes
> fw crash.
>
> This commit disables ps_mode by default instead of enabling it.
>
> Required code is extracted from mwifiex_drv_set_power().
>
> Signed-off-by: Tsuchiya Yuto <kitakar@...il.com>

You should read up on WIPHY_FLAG_PS_ON_BY_DEFAULT and
CONFIG_CFG80211_DEFAULT_PS, and set/respect those appropriately (hint:
mwifiex sets WIPHY_FLAG_PS_ON_BY_DEFAULT, and your patch makes this a
lie). Also, this seems like a quirk that you haven't properly worked
out -- if you're working on a quirk framework in your other series,
you should just key into that.

For the record, Chrome OS supports plenty of mwifiex systems with 8897
(SDIO only) and 8997 (PCIe), with PS enabled, and you're hurting
those. Your problem sounds to be exclusively a problem with the PCIe
8897 firmware.

As-is, NAK.

Brian