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Subject: Re: [PATCH wireless v2] wifi: rtw88: sdio: Always use two consecutive
 bytes for word operations
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <20230515195043.572375-1-martin.blumenstingl@googlemail.com>
References: <20230515195043.572375-1-martin.blumenstingl@googlemail.com>
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc:     linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
        pkshih@realtek.com, tony0620emma@gmail.com,
        jernej.skrabec@gmail.com, linux-sunxi@lists.linux.dev,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Larry Finger <Larry.Finger@lwfinger.net>,
        Rudi Heitbaum <rudi@heitbaum.com>
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.7.3
Message-ID: <168430378778.24096.6636792783589733385.kvalo@kernel.org>
Date:   Wed, 17 May 2023 06:09:53 +0000 (UTC)
Precedence: bulk

Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:

> The Allwinner sunxi-mmc controller cannot handle word (16 bit)
> transfers. So and sdio_{read,write}w fails with messages like the
> following example using an RTL8822BS (but the same problems were also
> observed with RTL8822CS and RTL8723DS chips):
>   rtw_8822bs mmc1:0001:1: Firmware version 27.2.0, H2C version 13
>   sunxi-mmc 4021000.mmc: unaligned scatterlist: os f80 length 2
>   sunxi-mmc 4021000.mmc: map DMA failed
>   rtw_8822bs mmc1:0001:1: sdio read16 failed (0x10230): -22
> 
> Use two consecutive single byte accesses for word operations instead. It
> turns out that upon closer inspection this is also what the vendor
> driver does, even though it does have support for sdio_{read,write}w. So
> we can conclude that the rtw88 chips do support word access but only on
> SDIO controllers that also support it. Since there's no way to detect if
> the controller supports word access or not the rtw88 sdio driver
> switches to the easiest approach: avoiding word access.
> 
> Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
> Closes: https://lore.kernel.org/linux-wireless/527585e5-9cdd-66ed-c3af-6da162f4b720@lwfinger.net/
> Reported-by: Rudi Heitbaum <rudi@heitbaum.com>
> Link: https://github.com/LibreELEC/LibreELEC.tv/pull/7837#issue-1708469467
> Fixes: 65371a3f14e7 ("wifi: rtw88: sdio: Add HCI implementation for SDIO based chipsets")
> Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Patch applied to wireless.git, thanks.

cb0ddaaa5db0 wifi: rtw88: sdio: Always use two consecutive bytes for word operations

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20230515195043.572375-1-martin.blumenstingl@googlemail.com/

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