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

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Message-ID: <20200917113846.GX3515672@ulmo>
Date:   Thu, 17 Sep 2020 13:38:46 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 12/34] i2c: tegra: Use clk-bulk helpers

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.

Thierry

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