linux-kernel - RE: [PATCH 2/2] i2c: designware: Add support for a bus clock

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Date:   Tue, 17 Jul 2018 12:42:02 +0000
From:   Phil Edworthy <phil.edworthy@...esas.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Simon Horman <horms@...ge.net.au>
CC:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: RE: [PATCH 2/2] i2c: designware: Add support for a bus clock

Hi Simon, Andy,

On 17 July 2018 13:24, Andy Shevchenko wrote:
> On Tue, 2018-07-17 at 14:07 +0200, Simon Horman wrote:
> > On Mon, Jul 16, 2018 at 09:59:13AM +0100, Phil Edworthy wrote:
> > > The Synopsys I2C Controller has a bus clock, but typically SoCs hide
> > > this away.
> > > However, on some SoCs you need to explicity enable the bus clock in
> > > order to access the registers.
> > > Therefore, enable an optional bus clock specified by DT.
> 
> > > +		/* Optional bus clock */
> > > +		if (!IS_ERR(dev->busclk)) {
> >
> > I suspect that error values stored in dev->busclk,  other than
> > -ENOENT, should be treated as errors.
IS_ERR catches all errors and is the correct way to check the value
returned by devm_clk_get.

> While your point sounds valid (don't remember how clk_get() is
> implemented), NULL is also OK to have.
Ok as in there is no bus clock, right?
So it should be:
 if (!IS_ERR_OR_NULL (dev->busclk)) {

Thanks
Phil