linux-kernel - Re: [PATCH 2/2] drm: adv7511: Add support for i2c_new_secondary

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Date:   Wed, 7 Feb 2018 23:40:00 +0000
From:   Kieran Bingham <kieran.bingham@...asonboard.com>
To:     Archit Taneja <architt@...eaurora.org>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Cc:     Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>,
        David Airlie <airlied@...ux.ie>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        John Stultz <john.stultz@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Bhumika Goyal <bhumirks@...il.com>,
        Inki Dae <inki.dae@...sung.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Subject: Re: [PATCH 2/2] drm: adv7511: Add support for
 i2c_new_secondary_device

Hi Archit,

On 07/02/18 12:33, Kieran Bingham wrote:
> Hi Archit,
> 
> Thank you for your review,
> 

<snip>

>>>       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 :)

I appear to be using platform specific maths specific to a non-conforming
platform or universe :-)

Sorry for the incorrect assertion here. - I mixed up 8bit and 7bit values.

The offsets are valid (when calculated correctly) - however - as per my reply to
Laurent - I believe the patch which determined the offsets was using the wrong
base :).

Also - due to a hardware issue on the ADV7511 - the Wheat (as the only known
user of two chips on the same bus) will need to be updated to ensure the current
assignments don't conflict.

--
Kieran