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Subject: Re: [PATCH 2/2] drm: adv7511: Add support for
 i2c_new_secondary_device
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
        Jean-Michel Hautbois <jean-michel.hautbois@vodalys.com>,
        David Airlie <airlied@linux.ie>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Archit Taneja <architt@codeaurora.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        John Stultz <john.stultz@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Hans Verkuil <hans.verkuil@cisco.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Bhumika Goyal <bhumirks@gmail.com>,
        Inki Dae <inki.dae@samsung.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
References: <1516625389-6362-1-git-send-email-kieran.bingham@ideasonboard.com>
 <1516625389-6362-3-git-send-email-kieran.bingham@ideasonboard.com>
 <1650729.pzuqXiNcLL@avalon>
From:   Kieran Bingham <kieran.bingham@ideasonboard.com>
Organization: Ideas on Board
Message-ID: <22aa9d42-e7df-cbe7-4044-3b120cd242c3@ideasonboard.com>
Date:   Wed, 7 Feb 2018 15:14:09 +0000
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Hi Laurent,

On 29/01/18 10:26, Laurent Pinchart wrote:
> Hi Kieran,
> 
> Thank you for the patch.

Thanks for your review,

> On Monday, 22 January 2018 14:50:00 EET Kieran Bingham wrote:
>> The ADV7511 has four 256-byte maps that can be accessed via the main I²C
>> ports. Each map has it own I²C address and acts as a standard slave
>> device on the I²C bus.
>>
>> Allow a device tree node to override the default addresses so that
>> address conflicts with other devices on the same bus may be resolved at
>> the board description level.
>>
>> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
>> ---
>>  .../bindings/display/bridge/adi,adv7511.txt        | 10 +++++-
> 
> I don't mind personally, but device tree maintainers usually ask for DT 
> bindings changes to be split to a separate patch.
> 
>>  drivers/gpu/drm/bridge/adv7511/adv7511.h           |  4 +++
>>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c       | 36 ++++++++++++-------
>>  3 files changed, 37 insertions(+), 13 deletions(-)
>>
>> diff --git
>> a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>> b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>> index 0047b1394c70..f6bb9f6d3f48 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt
>> @@ -70,6 +70,9 @@ Optional properties:
>>    rather than generate its own timings for HDMI output.
>>  - clocks: from common clock binding: reference to the CEC clock.
>>  - clock-names: from common clock binding: must be "cec".
>> +- reg-names : Names of maps with programmable addresses.
>> +	It can contain any map needing a non-default address.
>> +	Possible maps names are : "main", "edid", "cec", "packet"
> 
> Is the reg-names property (and the additional maps) mandatory or optional ? > If mandatory you should also update the existing DT sources that use those
> bindings.

They are currently optional. I do prefer it that way - but perhaps due to an
issue mentioned below we might need to make this driver mandatory ?


> If optional you should define which I2C addresses will be used when 
> the maps are not specified > (and in that case I think we should go for the
> addresses listed as default in the datasheet, which correspond to the current 
> driver implementation when the main address is 0x3d/0x7a).

The current addresses do not correspond to the datasheet, even when the
implementation main address is set to 0x3d.

Thus, in my opinion - they are currently 'wrong' - but perhaps changing them is
considered breakage too.

A particular issue will arise here too - as on this device - when the device is
in low-power mode (after probe, before use) - the maps will respond on their
*hardware default* addresses (the ones implemented in this patch), and thus
consume that address on the I2C bus regardless of their settings in the driver.


> You should also update the definition of the reg property that currently just 
> states
> 
> - reg: I2C slave address
> 
> And finally you might want to define the term "map" in this context. Here's a 
> proposal (if we make all maps mandatory).
> 
> The ADV7511 internal registers are split into four pages exposed through 
> different I2C addresses, creating four register maps. The I2C addresses of all 
> four maps shall be specified by the reg and reg-names property.
> 
> - reg: I2C slave addresses, one per reg-names entry
> - reg-names: map names, shall be "main", "edid", "cec", "packet"
> 
>>  Required nodes:
>>  
>> @@ -88,7 +91,12 @@ Example
>>  
>>  	adv7511w: hdmi@39 {
>>  		compatible = "adi,adv7511w";
>> -		reg = <39>;
>> +		/*
>> +		 * The EDID page will be accessible on address 0x66 on the i2c
>> +		 * bus. All other maps continue to use their default addresses.
>> +		 */
>> +		reg = <0x39 0x66>;
>> +		reg-names = "main", "edid";
>>  		interrupt-parent = <&gpio3>;
>>  		interrupts = <29 IRQ_TYPE_EDGE_FALLING>;
>>  		clocks = <&cec_clock>;
>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h
>> b/drivers/gpu/drm/bridge/adv7511/adv7511.h
>> index d034b2cb5eee..7d81ce3808e0 100644
>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
>> @@ -53,8 +53,10 @@
>>  #define ADV7511_REG_POWER			0x41
>>  #define ADV7511_REG_STATUS			0x42
>>  #define ADV7511_REG_EDID_I2C_ADDR		0x43
>> +#define ADV7511_REG_EDID_I2C_ADDR_DEFAULT	0x3f
>>  #define ADV7511_REG_PACKET_ENABLE1		0x44
>>  #define ADV7511_REG_PACKET_I2C_ADDR		0x45
>> +#define ADV7511_REG_PACKET_I2C_ADDR_DEFAULT	0x38
>>  #define ADV7511_REG_DSD_ENABLE			0x46
>>  #define ADV7511_REG_VIDEO_INPUT_CFG2		0x48
>>  #define ADV7511_REG_INFOFRAME_UPDATE		0x4a
>> @@ -89,6 +91,7 @@
>>  #define ADV7511_REG_TMDS_CLOCK_INV		0xde
>>  #define ADV7511_REG_ARC_CTRL			0xdf
>>  #define ADV7511_REG_CEC_I2C_ADDR		0xe1
>> +#define ADV7511_REG_CEC_I2C_ADDR_DEFAULT	0x3c
>>  #define ADV7511_REG_CEC_CTRL			0xe2
>>  #define ADV7511_REG_CHIP_ID_HIGH		0xf5
>>  #define ADV7511_REG_CHIP_ID_LOW			0xf6
>> @@ -322,6 +325,7 @@ struct adv7511 {
>>  	struct i2c_client *i2c_main;
>>  	struct i2c_client *i2c_edid;
>>  	struct i2c_client *i2c_cec;
>> +	struct i2c_client *i2c_packet;
>>  
>>  	struct regmap *regmap;
>>  	struct regmap *regmap_cec;
>> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> index efa29db5fc2b..7ec33837752b 100644
>> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
>> @@ -969,8 +969,8 @@ static int adv7511_init_cec_regmap(struct adv7511 *adv)
>> {
>>  	int ret;
>>  
>> -	adv->i2c_cec = i2c_new_dummy(adv->i2c_main->adapter,
>> -				     adv->i2c_main->addr - 1);
>> +	adv->i2c_cec = i2c_new_secondary_device(adv->i2c_main, "cec",
>> +					ADV7511_REG_CEC_I2C_ADDR_DEFAULT);
>>  	if (!adv->i2c_cec)
>>  		return -ENOMEM;
>>  	i2c_set_clientdata(adv->i2c_cec, adv);
>> @@ -1082,8 +1082,6 @@ static int adv7511_probe(struct i2c_client *i2c, const
>> struct i2c_device_id *id)
>>  	struct adv7511_link_config link_config;
>>  	struct adv7511 *adv7511;
>>  	struct device *dev = &i2c->dev;
>> -	unsigned int main_i2c_addr = i2c->addr << 1;
>> -	unsigned int edid_i2c_addr = main_i2c_addr + 4;
>>  	unsigned int val;
>>  	int ret;
>>  
>> @@ -1153,24 +1151,35 @@ static int adv7511_probe(struct i2c_client *i2c,
>> const struct i2c_device_id *id)
>>  	if (ret)
>>  		goto uninit_regulators;
>>  
>> -	regmap_write(adv7511->regmap, ADV7511_REG_EDID_I2C_ADDR, edid_i2c_addr);
>> -	regmap_write(adv7511->regmap, ADV7511_REG_PACKET_I2C_ADDR,
>> -		     main_i2c_addr - 0xa);
>> -	regmap_write(adv7511->regmap, ADV7511_REG_CEC_I2C_ADDR,
>> -		     main_i2c_addr - 2);
>> -
>>  	adv7511_packet_disable(adv7511, 0xffff);
>>  
>> -	adv7511->i2c_edid = i2c_new_dummy(i2c->adapter, edid_i2c_addr >> 1);
>> +	adv7511->i2c_edid = i2c_new_secondary_device(i2c, "edid",
>> +					ADV7511_REG_EDID_I2C_ADDR_DEFAULT);
>>  	if (!adv7511->i2c_edid) {
>>  		ret = -ENOMEM;
> 
> I wonder if this is the right error code. Maybe -EINVAL ? In most cases errors 
> will be caused by invalid addresses (out of memory and device_register() 
> failures can happen too but should be less common).

It's arbitrary, as multiple error paths simply return NULL, but I think you are
right - the 'most common' fault here is likely to be an in use address.

-ENOMEM was chosen here to mirror the equivalent code returned from the adv7604
driver.

Either way - -EINVAL does feel better at the moment. Although when mirrored back
to the ADV7604 that becomes a distinct change there.

I don't think that matters though - so I'll apply this fix to both patches.


> 
> It would be nice if i2c_new_secondary_device() returned an ERR_PTR, but that's 
> out of scope.

I was about to say - well I'll add this, but the reality is it might require
updating all users of i2c_new_device, and i2c_new_dummy. Updating
i2c_new_secondary_device() on it's own seems a bit pointless otherwise.

And that is definitely out of scope for the amount of time I currently have :D


>>  		goto uninit_regulators;
>>  	}
>>  
>> +	regmap_write(adv7511->regmap, ADV7511_REG_EDID_I2C_ADDR,
>> +		     adv7511->i2c_edid->addr << 1);
>> +
>>  	ret = adv7511_init_cec_regmap(adv7511);
>>  	if (ret)
>>  		goto err_i2c_unregister_edid;
>>  
>> +	regmap_write(adv7511->regmap, ADV7511_REG_CEC_I2C_ADDR,
>> +		     adv7511->i2c_cec->addr << 1);
>> +
>> +	adv7511->i2c_packet = i2c_new_secondary_device(i2c, "packet",
>> +					ADV7511_REG_PACKET_I2C_ADDR_DEFAULT);
>> +	if (!adv7511->i2c_packet) {
>> +		ret = -ENOMEM;
>> +		goto err_unregister_cec;
>> +	}
>> +
>> +	regmap_write(adv7511->regmap, ADV7511_REG_PACKET_I2C_ADDR,
>> +		     adv7511->i2c_packet->addr << 1);
>> +
>>  	INIT_WORK(&adv7511->hpd_work, adv7511_hpd_work);
>>  
>>  	if (i2c->irq) {
>> @@ -1181,7 +1190,7 @@ static int adv7511_probe(struct i2c_client *i2c, const
>> struct i2c_device_id *id)
>>  						IRQF_ONESHOT, dev_name(dev),
>>  						adv7511);
>>  		if (ret)
>> -			goto err_unregister_cec;
>> +			goto err_unregister_packet;
>>  	}
>>  
>>  	adv7511_power_off(adv7511);
>> @@ -1203,6 +1212,8 @@ static int adv7511_probe(struct i2c_client *i2c, const
>> struct i2c_device_id *id)
>>  	adv7511_audio_init(dev, adv7511);
>>  	return 0;
>>  
>> +err_unregister_packet:
>> +	i2c_unregister_device(adv7511->i2c_packet);
>>  err_unregister_cec:
>>  	i2c_unregister_device(adv7511->i2c_cec);
>>  	if (adv7511->cec_clk)
>> @@ -1234,6 +1245,7 @@ static int adv7511_remove(struct i2c_client *i2c)
>>  	cec_unregister_adapter(adv7511->cec_adap);
>>  
>>  	i2c_unregister_device(adv7511->i2c_edid);
>> +	i2c_unregister_device(adv7511->i2c_packet);
>>  
>>  	return 0;
>>  }
>