Hi Rob,
On 13/08/18 18:45, Rob Herring wrote:
> On Thu, Aug 09, 2018 at 08:29:44PM +0100, Kieran Bingham wrote:
>> The ADV748x supports configurable slave addresses for its I2C pages.
>> Document the page names, and provide an example for setting each of the
>> pages explicitly.
>
> It would be good to say why you need this.
In fact - I should probably have added a fixes tag here, which would
have added more context:
Fixes: 67537fe960e5 ("media: i2c: adv748x: Add support for
i2c_new_secondary_device")
Should I repost with this fixes tag?
Or can it be collected with the RB tag?
> The only use I can think of
> is if there are other devices on the bus and you need to make sure the
> addresses don't conflict.
Yes, precisely. This driver has 'slave pages' which are created and
mapped by the driver. The device has default addresses which are used by
the driver - but it's very easy for these to conflict with other devices
on the same I2C bus.
Because the mappings are simply a software construct, we have a means to
specify the desired mappings through DT at the board level - which
allows the boards to ensure that conflicts do not appear.
> Arguably, that information could be figured out without this in DT.
How so ?
Scanning the bus is error prone, and dependant upon driver state (and
presence), and we have no means currently of requesting 'free/unused'
addresses from the I2C core framework.
> Regardless,
>
> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
Thank you.
--
Regards
Kieran
>
>>
>> Signed-off-by: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
>>
>> ---
>> v2:
>> - Fix commit message
>> - Extend documentation for the "required property" reg:
>>
>> v3
>> - Fix missing comment from Laurent.
>> - correct the reg descrption
>> ---
>> .../devicetree/bindings/media/i2c/adv748x.txt | 16 ++++++++++++++--
>> 1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/adv748x.txt b/Documentation/devicetree/bindings/media/i2c/adv748x.txt
>> index 21ffb5ed8183..25a02496f4ba 100644
>> --- a/Documentation/devicetree/bindings/media/i2c/adv748x.txt
>> +++ b/Documentation/devicetree/bindings/media/i2c/adv748x.txt
>> @@ -10,7 +10,11 @@ Required Properties:
>> - "adi,adv7481" for the ADV7481
>> - "adi,adv7482" for the ADV7482
>>
>> - - reg: I2C slave address
>> + - reg: I2C slave addresses
>> + The ADV748x has up to twelve 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. The main address is mandatory, others are
>> + optional and remain at default values if not specified.
>>
>> Optional Properties:
>>
>> @@ -18,6 +22,11 @@ Optional Properties:
>> "intrq3". All interrupts are optional. The "intrq3" interrupt
>> is only available on the adv7481
>> - interrupts: Specify the interrupt lines for the ADV748x
>> + - reg-names : Names of maps with programmable addresses.
>> + It shall contain all maps needing a non-default address.
>> + Possible map names are:
>> + "main", "dpll", "cp", "hdmi", "edid", "repeater",
>> + "infoframe", "cbus", "cec", "sdp", "txa", "txb"
>>
>> The device node must contain one 'port' child node per device input and output
>> port, in accordance with the video interface bindings defined in
>> @@ -47,7 +56,10 @@ Example:
>>
>> video-receiver@70 {
>> compatible = "adi,adv7482";
>> - reg = <0x70>;
>> + reg = <0x70 0x71 0x72 0x73 0x74 0x75
>> + 0x60 0x61 0x62 0x63 0x64 0x65>;
>> + reg-names = "main", "dpll", "cp", "hdmi", "edid", "repeater",
>> + "infoframe", "cbus", "cec", "sdp", "txa", "txb";
>>
>> #address-cells = <1>;
>> #size-cells = <0>;
>> --
>> 2.17.1
>>
>> --
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--
Regards
--
Kieran
