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Subject: Re: [PATCH v2 1/2] drm/bridge: sii902x: Enable I/O and core VCC
 supplies if present
To:     devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Mark Brown <broonie@kernel.org>,
        Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20200924200507.1175888-1-mr.nuke.me@gmail.com>
 <20200928173056.1674274-1-mr.nuke.me@gmail.com>
From:   "Alex G." <mr.nuke.me@gmail.com>
Message-ID: <d74c7626-8f16-db85-c23f-79bf0cc400d0@gmail.com>
Date:   Mon, 19 Oct 2020 20:24:40 -0500
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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?

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);
> +
>   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;
>   }
>