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Subject: Re: [PATCH 2/2] drm: adv7511: Add support for
 i2c_new_secondary_device
To:     Archit Taneja <architt@codeaurora.org>,
        linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org
Cc:     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>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.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>
 <e42ec168-5aff-8b8b-2307-d57a662dd395@codeaurora.org>
From:   Kieran Bingham <kieran.bingham@ideasonboard.com>
Organization: Ideas on Board
Message-ID: <5890b343-e908-688b-ba03-84c1f76411f3@ideasonboard.com>
Date:   Wed, 7 Feb 2018 12:33:51 +0000
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Hi Archit,

Thank you for your review,

On 29/01/18 04:11, Archit Taneja wrote:
> Hi,
> 
> On 01/22/2018 06:20 PM, 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 +++++-
>>   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"
>>     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
> 
> Minor comment: The defines above make look like new register
> defines. It would be nice to remove the "REG_" from them, and
> place them somewhere after the register definitions.


Sure.


>>   #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);
> 
> This patch avoids deriving the CEC/EDID map addresses from the main map. I think
> this would break what the original patch tried to do:

That was intentional.

The ADV7511 data-sheet defines default addresses for these maps.
 (or rather the hardware does)

> 
> d25a4cbba4b9da7c2d674b2f8ecf84af1b24988e
> "drm/bridge: adv7511: add support for the 2nd chip"
> 
> Maybe the default macros can be a function of the main address?

I'm loathed to do that, because then intrinsic knowledge must be known that if I
define a device at address X ... it will also use magic offset A B and C.

IMO - the driver should define the defaults to match the hardware.

Anything else is an override ...


<Welcoming comments, and arguments here>


>> +    adv->i2c_cec = i2c_new_secondary_device(adv->i2c_main, "cec",
>> +                    ADV7511_REG_CEC_I2C_ADDR_DEFAULT);
> 
> Also, I'm a bit unclear on the default address values. For example, previously,
> the CEC
> address was calculated as "adv->i2c_main->addr - 1", which is 0x38. The new
> CEC_I2C_ADDR_DEFAULT
> define sets it to 0x3c.


The registers defined in the programming guide [0] define default addresses
which is set by the hardware (and noteworthy, reset to; at low power mode!)

Page : Register : Default   : Purpose

165  : 0x43     : 0x3f << 1 : EDID Memory Address
166  : 0x45     : 0x38 << 1 : Packet Memory I2C Map Address
181  : 0xE1     : 0x3c << 1 : CEC ID

Actually - I've just seen there's a good table at page 16 :D

The ADV7511 main register map can appear at either 0x39 or 0x3D depending on the
input to a pull-up/down pin.

Thus - that implies that perhaps Sergei must have been working on a device
located at 0x3D, to determine the offset of -1 ... but we have two values for
computing the offset depending on whether you start at 0x39 or 0x3D.

And also - I can't even be sure that I can infer the starting address, as the
offsets for the EDID and Packet do not correlate here.

[0]
http://www.analog.com/media/en/technical-documentation/user-guides/ADV7511_Programming_Guide.pdf

> Thanks,
> Archit
> 
>>       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;

This computation doesn't correspond to anything except a random (perhaps
platform specific) offset.


>>       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);


Packet address here is written as an offset of -0x0a, which gives 0x2f or 0x33 ... ?

I think these current offsets are platform specific to a specific platform :)

--
Regards

Kieran


>> -    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;
>>           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;
>>   }
>>
>