linux-kernel - Re: Debugging i2c : i2cdetect cant detect a device on i2c line

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Date:   Thu, 7 Sep 2023 20:36:32 +0700
From:   Bagas Sanjaya <bagasdotme@...il.com>
To:     Raul Piper <raulpblooper@...il.com>,
        <kernelnewbies@...nelnewbies.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        Linux Devicetree <devicetree@...r.kernel.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Andi Shyti <andi.shyti@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Subject: Re: Debugging i2c : i2cdetect cant detect a device on i2c line

[also Cc: devicetree and ARM folks]

On Thu, Sep 07, 2023 at 08:21:44AM +0530, Raul Piper wrote:
> Hello ,
> I am trying to detect an i2c device A on i2c1 line on  one of the Arm
> Cortex A7 platform but not able to see any device on a given address (
> 0x3d) .
> 
> Is there any parameters of i2c which i can change like rise/fall time
> , timeout etc in a device tree or kernel source and re test it?
> I have tried changing the i2c speed from 100KHz to 400 KHz  but no success.
> I have even tried removing the 1.5K pull ups on the i2c lines but no result.
> 
> So I wanted to know on what factors i2cdetect may not probe the device
> or show it on the hex dump.
> What parameters of i2c driver i can tinker and where? Is Platform dts
> is the only file i can modify and test with?
> Kernel is 5.51 .

Do you mean v5.15.y stable series?

> There are other 2-3 devices on the same lines which responds to
> i2cdetect with correct address but not this device (0x3D) .
> Its i2c address is also different from the current devices.
> 

Specifically, what device do you have this issue with?

Confused...

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