linux-kernel - Re: [PATCH 4/6] mfd: da9063: Disallow RTC on DA9063L

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Date:   Tue, 29 May 2018 08:55:06 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Steve Twiss <stwiss.opensource@...semi.com>
Cc:     Marek Vasut <marek.vasut@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Mark Brown <broonie@...nel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 4/6] mfd: da9063: Disallow RTC on DA9063L

On Thu, 24 May 2018, Steve Twiss wrote:

> Thanks Marek,
> 
> On 23 May 2018 12:42 Marek Vasut wrote,
> 
> > To: linux-kernel@...r.kernel.org
> > Cc: Marek Vasut <marek.vasut+renesas@...il.com>; Geert Uytterhoeven <geert+renesas@...der.be>; Lee Jones <lee.jones@...aro.org>; Mark Brown <broonie@...nel.org>; Steve Twiss <stwiss.opensource@...semi.com>; Wolfram Sang <wsa+renesas@...g-engineering.com>; linux-renesas-soc@...r.kernel.org
> > Subject: [PATCH 4/6] mfd: da9063: Disallow RTC on DA9063L
> >
> > The DA9063L does not contain RTC block, unlike the full DA9063.
> > Do not allow binding RTC driver on this variant of the chip.
> >
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@...il.com>
> > Cc: Geert Uytterhoeven <geert+renesas@...der.be>
> > Cc: Lee Jones <lee.jones@...aro.org>
> > Cc: Mark Brown <broonie@...nel.org>
> > Cc: Steve Twiss <stwiss.opensource@...semi.com>
> > Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>
> > Cc: linux-renesas-soc@...r.kernel.org
> > ---
> >  drivers/mfd/da9063-core.c | 18 +++++++++++-------
> >  1 file changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/mfd/da9063-core.c b/drivers/mfd/da9063-core.c index 7360b76b4f72..263c83006413 100644
> > --- a/drivers/mfd/da9063-core.c
> > +++ b/drivers/mfd/da9063-core.c
> > @@ -101,14 +101,14 @@ static const struct mfd_cell da9063_devs[] = {
> >  		.of_compatible = "dlg,da9063-onkey",
> >  	},
> >  	{
> > +		.name		= DA9063_DRVNAME_VIBRATION,
> > +	},
> > +	{	/* Only present on DA9063 , not on DA9063L */
> >  		.name		= DA9063_DRVNAME_RTC,
> >  		.num_resources	= ARRAY_SIZE(da9063_rtc_resources),
> >  		.resources	= da9063_rtc_resources,
> >  		.of_compatible	= "dlg,da9063-rtc",
> >  	},
> > -	{
> > -		.name		= DA9063_DRVNAME_VIBRATION,
> > -	},
> >  };
> >  
> >  static int da9063_clear_fault_log(struct da9063 *da9063) @@ -163,7 +163,7 @@ int da9063_device_init(struct da9063 *da9063, unsigned int irq)  {
> >  	struct da9063_pdata *pdata = da9063->dev->platform_data;
> >  	int model, variant_id, variant_code;
> > -	int ret;
> > +	int da9063_devs_len, ret;
> >  
> >  	ret = da9063_clear_fault_log(da9063);
> >  	if (ret < 0)
> > @@ -225,9 +225,13 @@ int da9063_device_init(struct da9063 *da9063, unsigned int irq)
> >  
> >  	da9063->irq_base = regmap_irq_chip_get_base(da9063->regmap_irq);
> >  
> > -	ret = mfd_add_devices(da9063->dev, -1, da9063_devs,
> > -			      ARRAY_SIZE(da9063_devs), NULL, da9063->irq_base,
> > -			      NULL);
> > +	da9063_devs_len = ARRAY_SIZE(da9063_devs);
> > +	/* RTC, the last device in the list, is only present on DA9063 */
> > +	if (da9063->type == PMIC_TYPE_DA9063L)
> > +		da9063_devs_len -= 1;
> > +
> > +	ret = mfd_add_devices(da9063->dev, -1, da9063_devs, da9063_devs_len,
> > +			      NULL, da9063->irq_base, NULL);
> >  	if (ret)
> >  		dev_err(da9063->dev, "Cannot add MFD cells\n");
> >  
> 
> MFD cells definitely has less impact than regmap_range and regmap_irq.
> I agree, there's no point in having a completely new 
> static const struct mfd_cell da9063l_devs[] = { ... }  for DA9063L

This solution is fragile.

I agree that a new MFD cell is not required in its entirety.  It
would however, be better to split out the RTC entry into a new one and
only register it when (da9063->type == PMIC_TYPE_DA9063).  This is a
better solution than messing around with passed struct sizes.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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