linux-kernel - Re: [PATCH V2 1/2] drm/bridge: adv7511: Allow IRQ to share GPIO pins

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Date: Thu, 4 Apr 2024 07:00:49 -0500
From: Adam Ford <aford173@...il.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: dri-devel@...ts.freedesktop.org, aford@...conembedded.com, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	devicetree@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/2] drm/bridge: adv7511: Allow IRQ to share GPIO pins

On Tue, Mar 5, 2024 at 2:18 AM Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hello Adam,
>
> Thank you for the patch.
>
> On Mon, Mar 04, 2024 at 06:48:57PM -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 GPIO, it won't be registered and the
> > hot-plug detect fails to function.
> >
> > Currently, the handler reads two registers and blindly
> > assumes one of them caused the interrupt and returns IRQ_HANDLED
> > unless there is an error. In order to properly do this, the IRQ
> > handler needs to check if it needs to handle the IRQ and return
> > IRQ_NONE if there is nothing to handle.  With the check added
> > and the return code properly indicating whether or not it there
> > was an IRQ, the IRQF_SHARED can be set to share a GPIO IRQ.
> >
> > Signed-off-by: Adam Ford <aford173@...il.com>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>


Gentle nudge on this one.   It's been about a month, and without it,
it is preventing hot-plug detection on one board for me.

Thanks

adam

>
> > ---
> > V2:  Add check to see if there is IRQ data to handle
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index b5518ff97165..f3b4616a8fb6 100644
> > --- 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 data */
> > +     if (!(irq0 & (ADV7511_INT0_HPD | ADV7511_INT0_EDID_READY)) &&
> > +         !(irq1 & ADV7511_INT1_DDC_ERROR))
> > +             return -ENODATA;
> > +
> >       regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0);
> >       regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1);
> >
> > @@ -1318,7 +1323,8 @@ 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),
> >                                               adv7511);
> >               if (ret)
> >                       goto err_unregister_audio;
>
> --
> Regards,
>
> Laurent Pinchart