Re: [PATCH] gpio: realtek-otto: fix GPIO line IRQ offset

[Sander Vanheule <sander@xxxxxxxxxxxxx>]

On Thu, 2021-10-28 at 13:23 +0300, Andy Shevchenko wrote:
> On Thu, Oct 28, 2021 at 11:52 AM Sander Vanheule <sander@xxxxxxxxxxxxx> wrote:
> > 
> > The irqchip uses one domain for all GPIO lines, so the line offset
> > should be determined w.r.t. the first line of the first port, not the
> > first line of the triggered port.
> > 
> > Fixes: 0d82fb1127fb ("gpio: Add Realtek Otto GPIO support")
> 
> Not sure it fixes anything (it wasn't working from day 1), but in any
> case the patch is good.

The original patch was tested using a GPIO line on port A, so the missing offset was
irrelevant there (as it was zero). After recently acquiring a new device, I was trying to
use a line on port C, which resulted in unhandled interrupts.

> 
> > Signed-off-by: Sander Vanheule <sander@xxxxxxxxxxxxx>
> > ---
> >  drivers/gpio/gpio-realtek-otto.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpio/gpio-realtek-otto.c b/drivers/gpio/gpio-realtek-otto.c
> > index eeeb39bc171d..bd75401b549d 100644
> > --- a/drivers/gpio/gpio-realtek-otto.c
> > +++ b/drivers/gpio/gpio-realtek-otto.c
> > @@ -205,7 +205,7 @@ static void realtek_gpio_irq_handler(struct irq_desc *desc)
> >                 status = realtek_gpio_read_isr(ctrl, lines_done / 8);
> >                 port_pin_count = min(gc->ngpio - lines_done, 8U);
> >                 for_each_set_bit(offset, &status, port_pin_count)
> > -                       generic_handle_domain_irq(gc->irq.domain, offset);
> > +                       generic_handle_domain_irq(gc->irq.domain, offset +
> > lines_done);
> 
> Looking into these '/ 8', '8U' sounds to me that it may be a good idea
> to switch to for_each_set_clump8(). But it's out of scope here.

For the current code, I could indeed have used for_each_set_clump8, instead of the u8
read_isr() accessor.

However, I'm also preparing support for the RTL9302 device I have recently acquired. On
RTL930x and RTL931x the port order is reversed, requiring different port order handling.
My plan is to provide different port_read_isr() functions for the different port orders,
that return the requested u8. I'll try to get that patch set out today as well.

Best,
Sander