From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kieran Bingham Subject: Re: [PATCH v3] dt-bindings: media: adv748x: Document re-mappable addresses Date: Mon, 13 Aug 2018 20:17:42 +0100 Message-ID: References: <20180809192944.7371-1-kieran.bingham@ideasonboard.com> <20180813174544.GA11379@rob-hp-laptop> Reply-To: kieran.bingham@ideasonboard.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180813174544.GA11379@rob-hp-laptop> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Laurent Pinchart , mchehab@kernel.org, Mark Rutland , Hans Verkuil , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org 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 Thank you. -- Regards Kieran > >> >> Signed-off-by: Kieran Bingham >> >> --- >> 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 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe devicetree" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- Regards -- Kieran