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

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Message-ID: <20240305004859.201085-1-aford173@gmail.com>
Date: Mon,  4 Mar 2024 18:48:57 -0600
From: Adam Ford <aford173@...il.com>
To: dri-devel@...ts.freedesktop.org
Cc: aford@...conembedded.com,
	laurent.pinchart@...asonboard.com,
	Adam Ford <aford173@...il.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>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	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: [PATCH V2 1/2] drm/bridge: adv7511: Allow IRQ to share GPIO pins

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>
---
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;
-- 
2.43.0