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Date:   Tue, 20 Oct 2020 09:16:28 +0200
From:   Sam Ravnborg <sam@ravnborg.org>
To:     "Alex G." <mr.nuke.me@gmail.com>
Cc:     devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Neil Armstrong <narmstrong@baylibre.com>,
        David Airlie <airlied@linux.ie>,
        Mark Brown <broonie@kernel.org>,
        Jonas Karlman <jonas@kwiboo.se>,
        open list <linux-kernel@vger.kernel.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Rob Herring <robh+dt@kernel.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Subject: Re: [PATCH v2 1/2] drm/bridge: sii902x: Enable I/O and core VCC
 supplies if present
Message-ID: <20201020071628.GA1737816@ravnborg.org>
References: <20200924200507.1175888-1-mr.nuke.me@gmail.com>
 <20200928173056.1674274-1-mr.nuke.me@gmail.com>
 <d74c7626-8f16-db85-c23f-79bf0cc400d0@gmail.com>
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In-Reply-To: <d74c7626-8f16-db85-c23f-79bf0cc400d0@gmail.com>
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Hi Alex.

On Mon, Oct 19, 2020 at 08:24:40PM -0500, Alex G. wrote:
> On 9/28/20 12:30 PM, Alexandru Gagniuc wrote:
> > On the SII9022, the IOVCC and CVCC12 supplies must reach the correct
> > voltage before the reset sequence is initiated. On most boards, this
> > assumption is true at boot-up, so initialization succeeds.
> > 
> > However, when we try to initialize the chip with incorrect supply
> > voltages, it will not respond to I2C requests. sii902x_probe() fails
> > with -ENXIO.
> > 
> > To resolve this, look for the "iovcc" and "cvcc12" regulators, and
> > make sure they are enabled before starting the reset sequence. If
> > these supplies are not available in devicetree, then they will default
> > to dummy-regulator. In that case everything will work like before.
> > 
> > This was observed on a STM32MP157C-DK2 booting in u-boot falcon mode.
> > On this board, the supplies would be set by the second stage
> > bootloader, which does not run in falcon mode.
> > 
> > Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> > ---
> > Changes since v1:
> >    * Fix return code after regulator_enable(sii902x->iovcc) fails (Fabio Estevam)
> >    * Use dev_err_probe() instead of dev_err() where appropriate (Sam Ravnborg)
> > 
> >   drivers/gpu/drm/bridge/sii902x.c | 54 ++++++++++++++++++++++++++++----
> >   1 file changed, 48 insertions(+), 6 deletions(-)
> 
> This patch seems to have entered fall dormancy. Did I miss somebody in the
> CC field?

I have lost the original mail/patch.
Can you resend with one fix - see below.

	Sam

> 
> Alex
> 
> 
> > diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> > index 33fd33f953ec..d15e9f2c0d8a 100644
> > --- a/drivers/gpu/drm/bridge/sii902x.c
> > +++ b/drivers/gpu/drm/bridge/sii902x.c
> > @@ -17,6 +17,7 @@
> >   #include <linux/i2c.h>
> >   #include <linux/module.h>
> >   #include <linux/regmap.h>
> > +#include <linux/regulator/consumer.h>
> >   #include <linux/clk.h>
> >   #include <drm/drm_atomic_helper.h>
> > @@ -168,6 +169,8 @@ struct sii902x {
> >   	struct drm_connector connector;
> >   	struct gpio_desc *reset_gpio;
> >   	struct i2c_mux_core *i2cmux;
> > +	struct regulator *iovcc;
> > +	struct regulator *cvcc12;
> >   	/*
> >   	 * Mutex protects audio and video functions from interfering
> >   	 * each other, by keeping their i2c command sequences atomic.
> > @@ -954,13 +957,13 @@ static const struct drm_bridge_timings default_sii902x_timings = {
> >   		 | DRM_BUS_FLAG_DE_HIGH,
> >   };
> > +static int sii902x_init(struct sii902x *sii902x);
Please re-arrange the code so this prototype is not needed.

> > +
> >   static int sii902x_probe(struct i2c_client *client,
> >   			 const struct i2c_device_id *id)
> >   {
> >   	struct device *dev = &client->dev;
> > -	unsigned int status = 0;
> >   	struct sii902x *sii902x;
> > -	u8 chipid[4];
> >   	int ret;
> >   	ret = i2c_check_functionality(client->adapter,
> > @@ -989,6 +992,43 @@ static int sii902x_probe(struct i2c_client *client,
> >   	mutex_init(&sii902x->mutex);
> > +	sii902x->iovcc = devm_regulator_get(dev, "iovcc");
> > +	if (IS_ERR(sii902x->iovcc))
> > +		return PTR_ERR(sii902x->iovcc);
> > +
> > +	sii902x->cvcc12 = devm_regulator_get(dev, "cvcc12");
> > +	if (IS_ERR(sii902x->cvcc12))
> > +		return PTR_ERR(sii902x->cvcc12);
> > +
> > +	ret = regulator_enable(sii902x->iovcc);
> > +	if (ret < 0) {
> > +		dev_err_probe(dev, ret, "Failed to enable iovcc supply");
> > +		return ret;
> > +	}
> > +
> > +	ret = regulator_enable(sii902x->cvcc12);
> > +	if (ret < 0) {
> > +		dev_err_probe(dev, ret, "Failed to enable cvcc12 supply");
> > +		regulator_disable(sii902x->iovcc);
> > +		return ret;
> > +	}
> > +
> > +	ret = sii902x_init(sii902x);
> > +	if (ret < 0) {
> > +		regulator_disable(sii902x->cvcc12);
> > +		regulator_disable(sii902x->iovcc);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int sii902x_init(struct sii902x *sii902x)
> > +{
> > +	struct device *dev = &sii902x->i2c->dev;
> > +	unsigned int status = 0;
> > +	u8 chipid[4];
> > +	int ret;
> > +
> >   	sii902x_reset(sii902x);
> >   	ret = regmap_write(sii902x->regmap, SII902X_REG_TPI_RQB, 0x0);
> > @@ -1012,11 +1052,11 @@ static int sii902x_probe(struct i2c_client *client,
> >   	regmap_read(sii902x->regmap, SII902X_INT_STATUS, &status);
> >   	regmap_write(sii902x->regmap, SII902X_INT_STATUS, status);
> > -	if (client->irq > 0) {
> > +	if (sii902x->i2c->irq > 0) {
> >   		regmap_write(sii902x->regmap, SII902X_INT_ENABLE,
> >   			     SII902X_HOTPLUG_EVENT);
> > -		ret = devm_request_threaded_irq(dev, client->irq, NULL,
> > +		ret = devm_request_threaded_irq(dev, sii902x->i2c->irq, NULL,
> >   						sii902x_interrupt,
> >   						IRQF_ONESHOT, dev_name(dev),
> >   						sii902x);
> > @@ -1031,9 +1071,9 @@ static int sii902x_probe(struct i2c_client *client,
> >   	sii902x_audio_codec_init(sii902x, dev);
> > -	i2c_set_clientdata(client, sii902x);
> > +	i2c_set_clientdata(sii902x->i2c, sii902x);
> > -	sii902x->i2cmux = i2c_mux_alloc(client->adapter, dev,
> > +	sii902x->i2cmux = i2c_mux_alloc(sii902x->i2c->adapter, dev,
> >   					1, 0, I2C_MUX_GATE,
> >   					sii902x_i2c_bypass_select,
> >   					sii902x_i2c_bypass_deselect);
> > @@ -1051,6 +1091,8 @@ static int sii902x_remove(struct i2c_client *client)
> >   	i2c_mux_del_adapters(sii902x->i2cmux);
> >   	drm_bridge_remove(&sii902x->bridge);
> > +	regulator_disable(sii902x->cvcc12);
> > +	regulator_disable(sii902x->iovcc);
> >   	return 0;
> >   }
> > 
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