linux-kernel - Re: [PATCH 2/2] leds: add Qualcomm PM8941 WLED driver

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Date:	Thu, 18 Dec 2014 15:43:53 -0800
From:	Bjorn <bjorn@...ymobile.com>
To:	Bryan Wu <cooloney@...il.com>
CC:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Richard Purdie <rpurdie@...ys.net>,
	Grant Likely <grant.likely@...aro.org>,
	"Cavin, Courtney" <Courtney.Cavin@...ymobile.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Linux LED Subsystem <linux-leds@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH 2/2] leds: add Qualcomm PM8941 WLED driver

On Tue 16 Dec 16:54 PST 2014, Bryan Wu wrote:

> On Mon, Dec 8, 2014 at 4:22 PM, Bjorn Andersson

[..]

> > diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig

[..]

> > +config LEDS_PM8941_WLED
> > +       tristate "LED support for the Qualcomm PM8941 WLED block"
> > +       depends on LEDS_CLASS
> > +       depends on REGMAP
> Here should be "select REGMAP"
> 

Thanks
> > +       help
> > +         This option enables support for the 'White' LED block
> > +         on Qualcomm PM8941 PMICs.
> > +

[..]

> > diff --git a/drivers/leds/leds-pm8941-wled.c b/drivers/leds/leds-pm8941-wled.c

[..]

> > +
> > +struct pm8941_wled_context {
> > +       struct pm8941_wled wled;
> > +       struct regmap *regmap;
> > +};
> > +
> 
> I think you can just add *regmap into pm8941_wled struct and
> pm8941_wled_context is redundant to me.
> 

Looks like a development leftover, I will fold it in.

[..]

> > +
> > +static int pm8941_wled_probe(struct platform_device *pdev)
> > +{
> > +       struct pm8941_wled_context *ctx;
> > +       struct regmap *regmap;
> > +       int rc;
> > +
> > +       regmap = dev_get_regmap(pdev->dev.parent, NULL);
> > +       if (!regmap) {
> > +               dev_err(&pdev->dev, "Unable to get regmap\n");
> > +               return -EINVAL;
> > +       }
> > +
> 
> Is this regmap mmio registers or i2c registers? Will the regmap
> operation sleep?
> 

It's a spmi regmap, in it's current configuration it's marked as "fast" i.e. it
will not sleep.

I discussed this with Courtney before sending the patch out and as this is used
for backlight we don't see a reason calling set_brightness() in atomic context.
If this changes I would send out a follow up patch.

> > +       ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
> > +       if (ctx == NULL)
> > +               return -ENOMEM;
> > +
> > +       ctx->regmap = regmap;
> > +
> > +       rc = pm8941_wled_configure(&ctx->wled, &pdev->dev);
> > +       if (rc)
> > +               return rc;
> > +
> > +       rc = pm8941_wled_setup(&ctx->wled);
> > +       if (rc)
> > +               return rc;
> > +
> > +       ctx->wled.cdev.brightness_set = pm8941_wled_set_brightness;
> > +
> > +       rc = led_classdev_register(&pdev->dev, &ctx->wled.cdev);
> > +       if (rc)
> > +               return rc;
> > +
> > +       platform_set_drvdata(pdev, ctx);
> > +       dev_info(&pdev->dev, "registered led \"%s\"\n", ctx->wled.cdev.name);
> > +
> > +       return 0;
> > +};
> > +

[..]

> > +MODULE_DESCRIPTION("pm8941 wled driver");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_ALIAS("platform: pm8941-wled");
> No space after ":"
> 

Oops.

Regards,
Bjorn
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