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References: <20240228113737.43434-1-aford173@gmail.com> <20240228163153.GH9863@pendragon.ideasonboard.com>
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From: Adam Ford <aford173@gmail.com>
Date: Sun, 3 Mar 2024 09:44:03 -0600
Message-ID: <CAHCN7xLGL5gMhd7Fo907gPScdD15KW==BHSorQMjbd-=k-E9OA@mail.gmail.com>
Subject: Re: [PATCH 1/2] drm/bridge: adv7511: Allow IRQ to share GPIO pins
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, 
	aford@beaconembedded.com, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Shawn Guo <shawnguo@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>, 
	Pengutronix Kernel Team <kernel@pengutronix.de>, Fabio Estevam <festevam@gmail.com>, 
	Andrzej Hajda <andrzej.hajda@intel.com>, Neil Armstrong <neil.armstrong@linaro.org>, 
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	Jernej Skrabec <jernej.skrabec@gmail.com>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
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On Wed, Feb 28, 2024 at 10:31=E2=80=AFAM Laurent Pinchart
<laurent.pinchart@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@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 =3D devm_request_threaded_irq(dev, i2c->irq, NULL,
> >                                               adv7511_irq_handler,
> > -                                             IRQF_ONESHOT, dev_name(de=
v),
> > +                                             IRQF_ONESHOT | IRQF_SHARE=
D,
> > +                                             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 =3D regmap_read(adv7511->regmap, ADV7511_REG_INT(0), &irq0);
>         if (ret < 0)
>                 return ret;
>
>         ret =3D 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.enc=
oder)
>                 schedule_work(&adv7511->hpd_work);
>
>         if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERR=
OR) {
>                 adv7511->edid_read =3D 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 =3D devid;
>         int ret;
>
>         ret =3D 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