linux-kernel - Re: [PATCH v7 12/34] i2c: tegra: Use clk-bulk helpers

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Date:   Thu, 17 Sep 2020 16:54:28 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Dmitry Osipenko <digetx@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-tegra@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 12/34] i2c: tegra: Use clk-bulk helpers

On Thu, Sep 17, 2020 at 2:38 PM Thierry Reding <thierry.reding@...il.com> wrote:
> On Wed, Sep 09, 2020 at 01:39:44AM +0300, Dmitry Osipenko wrote:
> > Use clk-bulk helpers and factor out clocks initialization into separate
> > function in order to make code cleaner.
> >
> > The clocks initialization now performed after reset-control initialization
> > in order to avoid a noisy -PROBE_DEFER errors on T186+ from the clk-bulk
> > helper which doesn't silence this error code. Hence reset_control_get()
> > now may return -EPROBE_DEFER on newer Tegra SoCs because they use BPMP
> > driver that provides reset controls and BPMP doesn't come up early during
> > boot. Previously rst was protected by the clocks retrieval and now this
> > patch makes dev_err_probe() to be used for the rst error handling.
> >
> > Suggested-by: Andy Shevchenko <andy.shevchenko@...il.com>
> > Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> > ---
> >  drivers/i2c/busses/i2c-tegra.c | 187 ++++++++++++---------------------
> >  1 file changed, 67 insertions(+), 120 deletions(-)
>
> This is tempting from a diffstat point of view, but the downside is that
> we can now no longer validate that all of the necessary clocks are given
> in device tree.
>
> Previously the driver would fail to probe the I2C controller if any of
> the expected clocks were not defined in device tree, but now it's just
> going to continue without it and not give any indication as to what's
> wrong.

You may print an error in the error path as previously. Since both
clocks are mandatory (as far as I understood the code) user will need
to check DT in any case.

-- 
With Best Regards,
Andy Shevchenko