linux-kernel - Re: [PATCH 2/2] drm/vc4: hdmi: Convert to gpiod

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Message-ID: <20210702131646.ppb5i7uz7kmmqs7g@gilmour>
Date:   Fri, 2 Jul 2021 15:16:46 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Nathan Chancellor <nathan@...nel.org>
Cc:     dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Eric Anholt <eric@...olt.net>, linux-kernel@...r.kernel.org,
        Linus Wallei <linus.walleij@...aro.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Dom Cobley <dom@...pberrypi.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Hans Verkuil <hans.verkuil@...co.com>
Subject: Re: [PATCH 2/2] drm/vc4: hdmi: Convert to gpiod

Hi Nathan,

On Thu, Jul 01, 2021 at 08:29:34PM -0700, Nathan Chancellor wrote:
> On Mon, May 24, 2021 at 03:18:52PM +0200, Maxime Ripard wrote:
> > The new gpiod interface takes care of parsing the GPIO flags and to
> > return the logical value when accessing an active-low GPIO, so switching
> > to it simplifies a lot the driver.
> > 
> > Signed-off-by: Maxime Ripard <maxime@...no.tech>
> > ---
> >  drivers/gpu/drm/vc4/vc4_hdmi.c | 24 +++++++-----------------
> >  drivers/gpu/drm/vc4/vc4_hdmi.h |  3 +--
> >  2 files changed, 8 insertions(+), 19 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > index ccc6c8079dc6..34622c59f6a7 100644
> > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > @@ -159,10 +159,9 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
> >  	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
> >  	bool connected = false;
> >  
> > -	if (vc4_hdmi->hpd_gpio) {
> > -		if (gpio_get_value_cansleep(vc4_hdmi->hpd_gpio) ^
> > -		    vc4_hdmi->hpd_active_low)
> > -			connected = true;
> > +	if (vc4_hdmi->hpd_gpio &&
> > +	    gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio)) {
> > +		connected = true;
> >  	} else if (drm_probe_ddc(vc4_hdmi->ddc)) {
> >  		connected = true;
> >  	} else if (HDMI_READ(HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED) {
> > @@ -1993,7 +1992,6 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
> >  	struct vc4_hdmi *vc4_hdmi;
> >  	struct drm_encoder *encoder;
> >  	struct device_node *ddc_node;
> > -	u32 value;
> >  	int ret;
> >  
> >  	vc4_hdmi = devm_kzalloc(dev, sizeof(*vc4_hdmi), GFP_KERNEL);
> > @@ -2031,18 +2029,10 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
> >  	/* Only use the GPIO HPD pin if present in the DT, otherwise
> >  	 * we'll use the HDMI core's register.
> >  	 */
> > -	if (of_find_property(dev->of_node, "hpd-gpios", &value)) {
> > -		enum of_gpio_flags hpd_gpio_flags;
> > -
> > -		vc4_hdmi->hpd_gpio = of_get_named_gpio_flags(dev->of_node,
> > -							     "hpd-gpios", 0,
> > -							     &hpd_gpio_flags);
> > -		if (vc4_hdmi->hpd_gpio < 0) {
> > -			ret = vc4_hdmi->hpd_gpio;
> > -			goto err_put_ddc;
> > -		}
> > -
> > -		vc4_hdmi->hpd_active_low = hpd_gpio_flags & OF_GPIO_ACTIVE_LOW;
> > +	vc4_hdmi->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN);
> > +	if (IS_ERR(vc4_hdmi->hpd_gpio)) {
> > +		ret = PTR_ERR(vc4_hdmi->hpd_gpio);
> > +		goto err_put_ddc;
> >  	}
> >  
> >  	vc4_hdmi->disable_wifi_frequencies =
> > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> > index 060bcaefbeb5..2688a55461d6 100644
> > --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> > @@ -146,8 +146,7 @@ struct vc4_hdmi {
> >  	/* VC5 Only */
> >  	void __iomem *rm_regs;
> >  
> > -	int hpd_gpio;
> > -	bool hpd_active_low;
> > +	struct gpio_desc *hpd_gpio;
> >  
> >  	/*
> >  	 * On some systems (like the RPi4), some modes are in the same
> > -- 
> > 2.31.1
> 
> This patch as commit 6800234ceee0 ("drm/vc4: hdmi: Convert to gpiod")
> causes my Raspberry Pi 3 to lock up shortly after boot in combination
> with commit 411efa18e4b0 ("drm/vc4: hdmi: Move the HSM clock enable to
> runtime_pm"). The serial console and ssh are completely unresponsive and
> I do not see any messages in dmesg with "debug ignore_loglevel". The
> device is running with a 32-bit kernel (multi_v7_defconfig) with 32-bit
> userspace. If there is any further information that I can provide,
> please let me know.

Thanks for reporting this. The same bug has been reported on wednesday
on the RPi repo here:
https://github.com/raspberrypi/linux/pull/4418

More specifically, this commit should fix it:
https://github.com/raspberrypi/linux/pull/4418/commits/6d404373c20a794da3d6a7b4f1373903183bb5d0

Even though it's based on the 5.10 kernel, it should apply without any
warning on a mainline tree. Let me know if it fixes your issue too

Maxime

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