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Message-ID: <d64b0d239972ed7b42a201d81ee1a7c4be96ece9.camel@svanheule.net>
Date: Tue, 26 Jul 2022 09:41:28 +0200
From: Sander Vanheule <sander@...nheule.net>
To: linux-gpio@...r.kernel.org, Bartosz Golaszewski <brgl@...ev.pl>,
Linus Walleij <linus.walleij@...aro.org>
Cc: linux-kernel@...r.kernel.org,
Andy Shevchenko <andy.shevchenko@...il.com>,
Luiz Angelo Daros de Luca <luizluca@...il.com>,
Birger Koblitz <mail@...ger-koblitz.de>,
Jan Hoffmann <jan@....eu>, Paul Cercueil <paul@...pouillou.net>
Subject: Re: [PATCH v2] gpio: realtek-otto: switch to 32-bit I/O
On Sun, 2022-07-24 at 13:31 +0200, Sander Vanheule 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 source
> 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@...il.com> # DGS-1210-52
> Reported-by: Birger Koblitz <mail@...ger-koblitz.de> # GS728TP
> Reported-by: Jan Hoffmann <jan@....eu> # 1920-16G
> Cc: Paul Cercueil <paul@...pouillou.net>
> Signed-off-by: Sander Vanheule <sander@...nheule.net>
> ---
...
> @@ -307,16 +308,17 @@ static int realtek_gpio_irq_set_affinity(struct irq_data
> *data,
> static int realtek_gpio_irq_init(struct gpio_chip *gc)
> {
> struct realtek_gpio_ctrl *ctrl = gpiochip_get_data(gc);
> - unsigned int port;
> + u32 mask_all = GENMASK(gc->ngpio, 0);
This should be GENMASK(gc->ngpio - 1, 0).
I'll wait a bit more for other comments before sending a v3.
Best,
Sander
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