Re: [PATCH wireless v1] wifi: rtw88: sdio: Always use two consecutive bytes for word operations

[Ping-Ke Shih]

On Mon, 2023-05-15 at 13:59 +0300, Kalle Valo wrote:
> 
> Ping-Ke Shih <pkshih@xxxxxxxxxxx> writes:
> 
> > > -----Original Message-----
> > > From: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
> > > Sent: Monday, May 15, 2023 4:04 AM
> > > To: linux-wireless@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx; Ping-Ke Shih <pkshih@xxxxxxxxxxx>; tony0620emma@xxxxxxxxx;
> > > kvalo@xxxxxxxxxx; Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>; Larry Finger
> > > <Larry.Finger@xxxxxxxxxxxx>; Rudi Heitbaum <rudi@xxxxxxxxxxxx>
> > > Subject: [PATCH wireless v1] wifi: rtw88: sdio: Always use two consecutive bytes for word
> > > operations
> > > 
> > > 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@xxxxxxxxxxxx>
> > > Closes: 
> > > https://lore.kernel.org/linux-wireless/527585e5-9cdd-66ed-c3af-6da162f4b720@xxxxxxxxxxxx/
> > 
> > "Closes:" seems not a regular tag. Use "Link: " instead.
> 
> Actually the documentation now talks about Closes tag:
> 
> https://docs.kernel.org/process/5.Posting.html#patch-formatting-and-changelogs
> 
> I guess this tag is a recent addition?
> 

Thanks for information. 

Then, this patch looks good to me.

Reviewed-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>