linux-kernel - Re: [PATCH v2 2/2] drm/bridge: sii902x: add optional power supplies

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Message-ID: <69a9da79-63df-6d0a-52e3-729ec8937484@samsung.com>
Date:   Mon, 14 May 2018 12:33:48 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Philippe CORNU <philippe.cornu@...com>,
        Archit Taneja <architt@...eaurora.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     Yannick FERTRE <yannick.fertre@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Alexandre TORGUE <alexandre.torgue@...com>
Subject: Re: [PATCH v2 2/2] drm/bridge: sii902x: add optional power supplies

On 14.05.2018 11:38, Philippe CORNU wrote:
> Hi Laurent, Archit, Andrzej & Yannick,
>
> Do you have any comments on this v2 driver part?
> (more details regarding v1/v2 differences in the cover letter 
> https://www.spinics.net/lists/dri-devel/msg174137.html)
>
> Thank you,
> Philippe :-)
>
>
> On 04/25/2018 09:53 AM, Philippe Cornu wrote:
>> Add the optional power supplies using the description found in
>> "SiI9022A/SiI9024A HDMI Transmitter Data Sheet (August 2016)".
>>
>> The sii902x input IOs are not "io safe" so it is important to
>> enable/disable voltage regulators during probe/remove phases to
>> avoid damages.

What exactly does it mean? Ie I understand that the chip has some
limitations, but why enabling/disabling regulators in probe/remove
should solve it?

Regards
Andrzej

>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@...com>
>> ---
>>   drivers/gpu/drm/bridge/sii902x.c | 38 ++++++++++++++++++++++++++++++++++----
>>   1 file changed, 34 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
>> index 60373d7eb220..c367d7b91ade 100644
>> --- a/drivers/gpu/drm/bridge/sii902x.c
>> +++ b/drivers/gpu/drm/bridge/sii902x.c
>> @@ -24,6 +24,7 @@
>>   #include <linux/i2c.h>
>>   #include <linux/module.h>
>>   #include <linux/regmap.h>
>> +#include <linux/regulator/consumer.h>
>>   
>>   #include <drm/drmP.h>
>>   #include <drm/drm_atomic_helper.h>
>> @@ -86,6 +87,7 @@ struct sii902x {
>>   	struct drm_bridge bridge;
>>   	struct drm_connector connector;
>>   	struct gpio_desc *reset_gpio;
>> +	struct regulator_bulk_data supplies[2];
>>   };
>>   
>>   static inline struct sii902x *bridge_to_sii902x(struct drm_bridge *bridge)
>> @@ -392,23 +394,42 @@ static int sii902x_probe(struct i2c_client *client,
>>   		return PTR_ERR(sii902x->reset_gpio);
>>   	}
>>   
>> +	sii902x->supplies[0].supply = "iovcc";
>> +	sii902x->supplies[1].supply = "vcc12";
>> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(sii902x->supplies),
>> +				      sii902x->supplies);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to get power supplies: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = regulator_bulk_enable(ARRAY_SIZE(sii902x->supplies),
>> +				    sii902x->supplies);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to enable power supplies: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	usleep_range(10000, 20000);
>> +
>>   	sii902x_reset(sii902x);
>>   
>>   	ret = regmap_write(sii902x->regmap, SII902X_REG_TPI_RQB, 0x0);
>>   	if (ret)
>> -		return ret;
>> +		goto err_disable_regulator;
>>   
>>   	ret = regmap_bulk_read(sii902x->regmap, SII902X_REG_CHIPID(0),
>>   			       &chipid, 4);
>>   	if (ret) {
>>   		dev_err(dev, "regmap_read failed %d\n", ret);
>> -		return ret;
>> +		goto err_disable_regulator;
>>   	}
>>   
>>   	if (chipid[0] != 0xb0) {
>>   		dev_err(dev, "Invalid chipid: %02x (expecting 0xb0)\n",
>>   			chipid[0]);
>> -		return -EINVAL;
>> +		ret = -EINVAL;
>> +		goto err_disable_regulator;
>>   	}
>>   
>>   	/* Clear all pending interrupts */
>> @@ -424,7 +445,7 @@ static int sii902x_probe(struct i2c_client *client,
>>   						IRQF_ONESHOT, dev_name(dev),
>>   						sii902x);
>>   		if (ret)
>> -			return ret;
>> +			goto err_disable_regulator;
>>   	}
>>   
>>   	sii902x->bridge.funcs = &sii902x_bridge_funcs;
>> @@ -434,6 +455,12 @@ static int sii902x_probe(struct i2c_client *client,
>>   	i2c_set_clientdata(client, sii902x);
>>   
>>   	return 0;
>> +
>> +err_disable_regulator:
>> +	regulator_bulk_disable(ARRAY_SIZE(sii902x->supplies),
>> +			       sii902x->supplies);
>> +
>> +	return ret;
>>   }
>>   
>>   static int sii902x_remove(struct i2c_client *client)
>> @@ -443,6 +470,9 @@ static int sii902x_remove(struct i2c_client *client)
>>   
>>   	drm_bridge_remove(&sii902x->bridge);
>>   
>> +	regulator_bulk_disable(ARRAY_SIZE(sii902x->supplies),
>> +			       sii902x->supplies);
>> +
>>   	return 0;
>>   }
>>