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Subject: Re: [PATCH] wifi: rtw88: fix race condition when doing H2C command
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <20221124064442.28042-1-pkshih@realtek.com>
References: <20221124064442.28042-1-pkshih@realtek.com>
To:     Ping-Ke Shih <pkshih@realtek.com>
Cc:     <tony0620emma@gmail.com>, <neo_jou@realtek.com>,
        <linux-wireless@vger.kernel.org>
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.7.3
Message-ID: <166964393792.4701.9928917528260013977.kvalo@kernel.org>
Date:   Mon, 28 Nov 2022 13:58:59 +0000 (UTC)
Precedence: bulk

Ping-Ke Shih <pkshih@realtek.com> wrote:

> From: Ji-Pin Jou <neo_jou@realtek.com>
> 
> For SDIO/USB interface, since the tranferring speed is slower than
> that in PCIE, it may have race condition when the driver sets down
> H2C command to the FW.
> 
> In the function rtw_fw_send_h2c_command, before the patch, box_reg
> is written first, then box_ex_reg is written. FW starts to work and
> fetch the value of box_ex_reg,  when the most significant byte of
> box_reg(4 bytes) is written. Meanwhile, for SDIO/USB interface,
> since the transferring speed is slow, the driver is still in writing
> the new value of box_ex_reg through the bus, and FW may get the
> wrong value of box_ex_reg at the moment.
> 
> To prevent the above driver/FW racing situation, box_ex_reg is
> written first then box_reg. Furthermore, it is written in 4 bytes at
> a time, instead of written in one byte one by one. It can increase
> the speed for SDIO/USB interface.
> 
> Signed-off-by: Ji-Pin Jou <neo_jou@realtek.com>
> Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
> Tested-by: Sascha Hauer <s.hauer@pengutronix.de>

Patch applied to wireless-next.git, thanks.

823092a53556 wifi: rtw88: fix race condition when doing H2C command

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20221124064442.28042-1-pkshih@realtek.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches