linux-kernel - Re: [PATCH] i2c: pca954x: Add option to skip disabling PCA954x Mux device

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Message-ID: <CAHp75Vdc13fGM==bE2uSSE27g0_BHN84U_P55kn5HsdNjDKyeA@mail.gmail.com>
Date:   Sun, 28 May 2017 01:31:20 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     ying.zhang22455@....com
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        jiafei.pan@....com, Priyanka Jain <Priyanka.Jain@...escale.com>
Subject: Re: [PATCH] i2c: pca954x: Add option to skip disabling PCA954x Mux device

On Tue, May 9, 2017 at 11:20 AM,  <ying.zhang22455@....com> wrote:

> On some Layerscape boards like LS2085ARDB/LS2080ARDB,
> input pull-up resistors on PCA954x Mux device are
> missing on board. So, if mux are disabled after powered-on,
> input lines will float leading to incorrect functionality.
>
> Hence, PCA954x Mux device should never be turned-off after
> power-on.
>
> Add option to skip disabling PCA954x Mux device
> if device tree contians "i2c-mux-never-disable" property
> for pca954x device node.

> +#ifdef CONFIG_ARCH_LAYERSCAPE

This is 99.99% is no go.

You need to spend more time to make the driver more generic (perhaps
using device property instead) and not using ugly #ifdefery.


-- 
With Best Regards,
Andy Shevchenko