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

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Message-ID: <ea6fbdbe-6ce5-0110-5590-083c7b697a85@st.com>
Date:   Thu, 19 Apr 2018 09:46:31 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:     Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.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>,
        Yannick FERTRE <yannick.fertre@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Alexandre TORGUE <alexandre.torgue@...com>
Subject: Re: [PATCH 2/2] drm/bridge: sii902x: add optional power supplies

Hi Laurent :-)

On 04/19/2018 10:20 AM, Laurent Pinchart wrote:
> Hi Philippe,
> 
> Thank you for the patch.
> 
> On Tuesday, 10 April 2018 08:19:27 EEST Philippe Cornu wrote:
>> Add the 3 optional power supplies using the exact description
>> found in the document named
>> "SiI9022A/SiI9024A HDMI Transmitter Data Sheet (August 2016)".
>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@...com>
>> ---
>> drivers/gpu/drm/bridge/sii902x.c | 39 +++++++++++++++++++++++++++++++++----
>> 1 file changed, 35 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/sii902x.c
>> b/drivers/gpu/drm/bridge/sii902x.c index 60373d7eb220..e17ba6db1ec8 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[3];
>>   };
>>
>>   static inline struct sii902x *bridge_to_sii902x(struct drm_bridge *bridge)
>> @@ -392,23 +394,43 @@ static int sii902x_probe(struct i2c_client *client,
>>   		return PTR_ERR(sii902x->reset_gpio);
>>   	}
>>
>> +	sii902x->supplies[0].supply = "iovcc";
>> +	sii902x->supplies[1].supply = "avcc12";
>> +	sii902x->supplies[2].supply = "cvcc12";
>> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(sii902x->supplies),
>> +				      sii902x->supplies);
>> +	if (ret) {
>> +		dev_err(dev, "regulator_bulk_get failed\n");
> 
> Maybe "failed to get power supplies" to be a bit more explicit ? And while at
> it, printing the value of ret too ?
> 

good point, I will do that in v2


>> +		return ret;
>> +	}
>> +
>> +	ret = regulator_bulk_enable(ARRAY_SIZE(sii902x->supplies),
>> +				    sii902x->supplies);
>> +	if (ret) {
>> +		dev_err(dev, "regulator_bulk_enable failed\n");
> 
> Same here ?
> 

agreed

>> +		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 +446,7 @@ 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 +456,12 @@ 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 +471,9 @@ static int sii902x_remove(struct i2c_client *client)
>>
>>   	drm_bridge_remove(&sii902x->bridge);
>>
>> +	regulator_bulk_disable(ARRAY_SIZE(sii902x->supplies),
>> +			       sii902x->supplies);
>> +
> 
> While this seems functionally correct, would it be useful to only enable power
> supplies when needed to save power ?
> 

that is a good point. I do not know well (yet) this bridge. Maybe I can 
add a 3rd patch with bridge pre_enable() and post_disable() containing 
reset & supplies management. Or I can put reset&supplies in bridge 
enable() & disable() but it could be a little messy.

Any opinion/advice?
Many thanks,
Philippe :-)

>>   	return 0;
>>   }
>