[PATCH 1/2] drm/bridge: adv7511: Allow IRQ to share GPIO pins

[Adam Ford]

On Wed, Feb 28, 2024 at 10:31 AM Laurent Pinchart
<laurent.pinchart at ideasonboard.com> wrote:
>
> Hi Adam,
>
> Thank you for the patch.
>
> On Wed, Feb 28, 2024 at 05:37:35AM -0600, Adam Ford wrote:
> > The IRQ registration currently assumes that the GPIO is
> > dedicated to it, but that may not necessarily be the case.
> > If the board has another device sharing the IRQ, it won't be
> > registered and the hot-plug detect fails.  This is easily
> > fixed by add the IRQF_SHARED flag.
> >
> > Signed-off-by: Adam Ford <aford173 at gmail.com>
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index b5518ff97165..21f08b2ae265 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > @@ -1318,7 +1318,8 @@ static int adv7511_probe(struct i2c_client *i2c)
> >
> >               ret = devm_request_threaded_irq(dev, i2c->irq, NULL,
> >                                               adv7511_irq_handler,
> > -                                             IRQF_ONESHOT, dev_name(dev),
> > +                                             IRQF_ONESHOT | IRQF_SHARED,
> > +                                             dev_name(dev),
>
> This looks fine, but the IRQ handler doesn't.

Thanks for the review.

>
> static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
> {
>         unsigned int irq0, irq1;
>         int ret;
>
>         ret = regmap_read(adv7511->regmap, ADV7511_REG_INT(0), &irq0);
>         if (ret < 0)
>                 return ret;
>
>         ret = regmap_read(adv7511->regmap, ADV7511_REG_INT(1), &irq1);
>         if (ret < 0)
>                 return ret;

If I did a check here and returned if there was no IRQ to handle,
would that be sufficient?

--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -477,6 +477,11 @@ static int adv7511_irq_process(struct adv7511
*adv7511, bool process_hpd)
        if (ret < 0)
                return ret;

+       /* If there is no IRQ to handle, exit indicating no IRQ handled */
+       if (!(irq0 & (ADV7511_INT0_HPD | ADV7511_INT0_EDID_READY)) &&
+          !(irq1 & ADV7511_INT1_DDC_ERROR))
+               return -1;
+
        regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0);
        regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);

With this, I would expect adv7511_irq_handler to return IRQ_NONE.  If
you're OK with that approach, I can do that.  If you want me to merge
adv7511_irq_handler, and adv7511_irq_process, I can do that too to
make the return codes a little more intuitive.

adam

>
>         regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0);
>         regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);
>
>         if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
>                 schedule_work(&adv7511->hpd_work);
>
>         if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) {
>                 adv7511->edid_read = true;
>
>                 if (adv7511->i2c_main->irq)
>                         wake_up_all(&adv7511->wq);
>         }
>
> #ifdef CONFIG_DRM_I2C_ADV7511_CEC
>         adv7511_cec_irq_process(adv7511, irq1);
> #endif
>
>         return 0;
> }
>
> static irqreturn_t adv7511_irq_handler(int irq, void *devid)
> {
>         struct adv7511 *adv7511 = devid;
>         int ret;
>
>         ret = adv7511_irq_process(adv7511, true);
>         return ret < 0 ? IRQ_NONE : IRQ_HANDLED;
> }
>
> The function will return IRQ_HANDLED as long as the registers can be
> read, even if they don't report any interrupt.
>
> >                                               adv7511);
> >               if (ret)
> >                       goto err_unregister_audio;
>
> --
> Regards,
>
> Laurent Pinchart