linux-kernel - Re: [PATCH v2 2/2] Add PWM fan controller driver for LGM SoC

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Message-ID: <20200625055818.nv5snblkm4nwvxw2@taurus.defre.kleine-koenig.org>
Date:   Thu, 25 Jun 2020 07:58:18 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     "Tanwar, Rahul" <rahul.tanwar@...ux.intel.com>
Cc:     Philipp Zabel <p.zabel@...gutronix.de>, linux-pwm@...r.kernel.org,
        thierry.reding@...il.com, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        andriy.shevchenko@...el.com, songjun.Wu@...el.com,
        cheol.yong.kim@...el.com, qi-ming.wu@...el.com,
        rahul.tanwar.linux@...il.com
Subject: Re: [PATCH v2 2/2] Add PWM fan controller driver for LGM SoC

On Thu, Jun 25, 2020 at 12:23:54PM +0800, Tanwar, Rahul wrote:
> 
> Hi Philipp,
> 
> On 18/6/2020 8:25 pm, Philipp Zabel wrote:
> > Hi Rahul,
> >
> > On Thu, 2020-06-18 at 20:05 +0800, Rahul Tanwar wrote:
> >> Intel Lightning Mountain(LGM) SoC contains a PWM fan controller.
> >> This PWM controller does not have any other consumer, it is a
> >> dedicated PWM controller for fan attached to the system. Add
> >> driver for this PWM fan controller.
> >>
> >> Signed-off-by: Rahul Tanwar <rahul.tanwar@...ux.intel.com>
> >> ---
> >>  drivers/pwm/Kconfig         |   9 +
> >>  drivers/pwm/Makefile        |   1 +
> >>  drivers/pwm/pwm-intel-lgm.c | 400 ++++++++++++++++++++++++++++++++++++++++++++
> >>  3 files changed, 410 insertions(+)
> >>  create mode 100644 drivers/pwm/pwm-intel-lgm.c
> >>
> > [...]
> >> diff --git a/drivers/pwm/pwm-intel-lgm.c b/drivers/pwm/pwm-intel-lgm.c
> >> new file mode 100644
> >> index 000000000000..3c7077acb161
> >> --- /dev/null
> >> +++ b/drivers/pwm/pwm-intel-lgm.c
> >> @@ -0,0 +1,400 @@
> > [...]
> >> +static int lgm_pwm_probe(struct platform_device *pdev)
> >> +{
> >> +	struct lgm_pwm_chip *pc;
> >> +	struct device *dev = &pdev->dev;
> >> +	void __iomem *io_base;
> >> +	int ret;
> >> +
> >> +	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
> >> +	if (!pc)
> >> +		return -ENOMEM;
> >> +
> >> +	io_base = devm_platform_ioremap_resource(pdev, 0);
> >> +	if (IS_ERR(io_base))
> >> +		return PTR_ERR(io_base);
> >> +
> >> +	pc->regmap = devm_regmap_init_mmio(dev, io_base, &pwm_regmap_config);
> >> +	if (IS_ERR(pc->regmap)) {
> >> +		ret = PTR_ERR(pc->regmap);
> >> +		dev_err(dev, "failed to init register map: %pe\n", pc->regmap);
> >> +		return ret;
> >> +	}
> >> +
> >> +	pc->clk = devm_clk_get(dev, NULL);
> >> +	if (IS_ERR(pc->clk)) {
> >> +		ret = PTR_ERR(pc->clk);
> >> +		dev_err(dev, "failed to get clock: %pe\n", pc->clk);
> >> +		return ret;
> >> +	}
> >> +
> >> +	pc->rst = devm_reset_control_get(dev, NULL);
> >> +	if (IS_ERR(pc->rst)) {
> >> +		ret = PTR_ERR(pc->rst);
> >> +		dev_err(dev, "failed to get reset control: %pe\n", pc->rst);
> >> +		return ret;
> >> +	}
> > Please use devm_reset_control_get_exclusive() to make it explicit an
> > that exclusive reset control is requested. Given how the reset control
> > is used, I think this driver could also use
> > devm_reset_control_get_shared() to potentially allow sharing a reset
> > line with other devices.
> 
> devm_reset_control_get() is a wrapper for devm_reset_control_get_exclusive().
> Code as below:
> static inline struct reset_control *devm_reset_control_get(
>                                 struct device *dev, const char *id)
> {
>         return devm_reset_control_get_exclusive(dev, id);
> }
> Am i missing something else?

Obviously you're missing the comment above of_reset_control_get about
some functions being compatibility wrappers.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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