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To:     Mark Brown <broonie@kernel.org>
From:   Stephen Boyd <sboyd@kernel.org>
In-Reply-To: <20181011145422.GG25351@sirena.org.uk>
Cc:     Charles Keepax <ckeepax@opensource.cirrus.com>,
        lee.jones@linaro.org, linus.walleij@linaro.org,
        mturquette@baylibre.com, robh+dt@kernel.org, mark.rutland@arm.com,
        lgirdwood@gmail.com, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, patches@opensource.cirrus.com,
        linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org
References: <20181008132542.19775-1-ckeepax@opensource.cirrus.com>
 <20181008132542.19775-3-ckeepax@opensource.cirrus.com>
 <153924124658.207691.10370075148426001371@swboyd.mtv.corp.google.com>
 <20181011145422.GG25351@sirena.org.uk>
Message-ID: <153928658292.5275.11321177725702156165@swboyd.mtv.corp.google.com>
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Subject: Re: [PATCH v2 3/5] clk: lochnagar: Add support for the Cirrus Logic Lochnagar
Date:   Thu, 11 Oct 2018 12:36:22 -0700
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Quoting Mark Brown (2018-10-11 07:54:22)
> On Thu, Oct 11, 2018 at 12:00:46AM -0700, Stephen Boyd wrote:
> > Quoting Charles Keepax (2018-10-08 06:25:40)
> =

> > > +struct lochnagar_regmap_clk {
> > > +       unsigned int cfg_reg;
> > > +       unsigned int ena_mask;
> > > +       unsigned int dir_mask;
> > > +
> > > +       unsigned int src_reg;
> > > +       unsigned int src_mask;
> =

> > Are these 32 bits or 16 bits or 8 bits? Please use a u32/u16/u8 so we
> > know the register width.
> =

> Note that regmap always uses unsigned int to represent registers
> regardless of the underlying physical register width, this can be an
> issue on reads since we pass the destination for the read in by address.
> =

> > > +struct lochnagar_clk_priv {
> > > +       struct device *dev;
> > > +       struct lochnagar *lochnagar;
> =

> > Is this used for anything besides getting the regmap? Can you get the
> > pointer to the parent in probe and use that to get the regmap pointer
> > from dev_get_remap() and also use the of_node of the parent to register
> =

> dev_get_regmap() is pretty expensive, I'd not advise using it in
> anything that might approximate a fast path.  It's kind of debatable
> when I2C gets involved but still feels wrong.

I'm suggesting the regmap is acquired in probe and a pointer is stored
here in this structure. That is not a fastpath as far as I know.