cb0ddaaa5d
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>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230515195043.572375-1-martin.blumenstingl@googlemail.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.