linux-kernel - Re: (EXT) Re: (EXT) Re: (EXT) Re: [PATCH] spi-imx: remove num-cs support, set num

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Message-ID: <CAOMZO5CVh==PQhB=WEWGyc01+YtcKB6B4t9v_B9b-jcD1Yu7dg@mail.gmail.com>
Date:   Sun, 13 Sep 2020 11:15:41 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-spi <linux-spi@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>
Subject: Re: (EXT) Re: (EXT) Re: (EXT) Re: [PATCH] spi-imx: remove num-cs
 support, set num_chipselect to 4

Hi Matthias,

On Mon, Sep 7, 2020 at 4:40 AM Matthias Schiffer
<matthias.schiffer@...tq-group.com> wrote:

> My rationale here is the following: As broken as the native CS of these
> controllers is, it isn't an unreasonable assumption that it is working
> fine with *some* devices or for some usecases - after all the support
> was implemented at some point, and has existed for a long time now. If
> we really want to remove this feature, a deprecation period with a
> warning message seems like the proper way to deal with this.
>
> Hypothetically, existing out-of-tree DTS could have used the native CS
> with num-cs set to 4. Always setting num_chipselect to 4 ensures that
> we don't break such DTS with the num-cs removal.

I still think this is more of a theoretical issue rather than a real
use case one.

Anyway, I have a proposal that I think will make both of us happy :-)

I will submit a patch shortly.