Re: [PATCH v3] gpio: realtek-otto: switch to 32-bit I/O

[Linus Walleij]

On Sun, Aug 7, 2022 at 9:21 PM Sander Vanheule <sander@xxxxxxxxxxxxx> wrote:

> By using 16-bit I/O on the GPIO peripheral, which is apparently not safe
> on MIPS, the IMR can end up containing garbage. This then results in
> interrupt triggers for lines that don't have an interrupt handler
> associated. The irq_desc lookup fails, and the ISR will not be cleared,
> keeping the CPU busy until reboot, or until another IMR operation
> restores the correct value. This situation appears to happen very
> rarely, for < 0.5% of IMR writes.
>
> Instead of using 8-bit or 16-bit I/O operations on the 32-bit memory
> mapped peripheral registers, switch to using 32-bit I/O only, operating
> on the entire bank for all single bit line settings. For 2-bit line
> settings, with 16-bit port values, stick to manual (un)packing.
>
> This issue has been seen on RTL8382M (HPE 1920-16G), RTL8391M (Netgear
> GS728TP v2), and RTL8393M (D-Link DGS-1210-52 F3, Zyxel GS1900-48).
>
> Reported-by: Luiz Angelo Daros de Luca <luizluca@xxxxxxxxx> # DGS-1210-52
> Reported-by: Birger Koblitz <mail@xxxxxxxxxxxxxxxxx> # GS728TP
> Reported-by: Jan Hoffmann <jan@xxxxxx> # 1920-16G
> Fixes: 0d82fb1127fb ("gpio: Add Realtek Otto GPIO support")
> Signed-off-by: Sander Vanheule <sander@xxxxxxxxxxxxx>
> Cc: Paul Cercueil <paul@xxxxxxxxxxxxxxx>

Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij