linux-kernel - Re: [PATCH v2 2/2] leds: add Qualcomm PM8941 WLED driver

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Date:	Thu, 29 Jan 2015 11:07:55 -0800
From:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
To:	"Ivan T. Ivanov" <iivanov@...sol.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>,
	Bryan Wu <cooloney@...il.com>,
	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>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] leds: add Qualcomm PM8941 WLED driver

On Thu 29 Jan 04:48 PST 2015, Ivan T. Ivanov wrote:

> 
> Hi Bjorn,
> 
> Just few nitpick comments. 
> 

Thanks.

> On Fri, 2015-01-23 at 16:54 -0800, Bjorn Andersson wrote:
> > From: Courtney Cavin cavin@...ymobile.com>
> > 
> > This adds support for the WLED ('White' LED) block on Qualcomm's
> > PM8941 PMICs.
> > 
> > Signed-off-by: Courtney Cavin cavin@...ymobile.com>
> > Signed-off-by: Bjorn Andersson andersson@...ymobile.com>
> > ---
> >  drivers/leds/Kconfig            |   8 +
> >  drivers/leds/Makefile           |   1 +
> >  drivers/leds/leds-pm8941-wled.c | 459 ++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 468 insertions(+)
> >  create mode 100644 drivers/leds/leds-pm8941-wled.c
> > 
> 
> <snip>
> 
> > +
> > +#define PM8941_WLED_REG_VAL_BASE               0x40
> > +#define  PM8941_WLED_REG_VAL_MAX               0xFFF
> > +
> > +#define PM8941_WLED_REG_MOD_EN                 0x46
> > +#define  PM8941_WLED_REG_MOD_EN_BIT            BIT(7)
> > +#define  PM8941_WLED_REG_MOD_EN_MASK           BIT(7)
> 
> Is it possible bit definitions to have same indentation like registers offsets?
> 

Well, yes ;)

But I like the separation, so unless Bryan would like me to change it I prefer
to leave it as is.

> > 
> > +struct pm8941_wled_config {
> > +       u32 i_boost_limit;
> > +       u32 ovp;
> > +       u32 switch_freq;
> > +       u32 num_strings;
> > +       u32 i_limit;
> > +       bool cs_out_en;
> > +       bool ext_gen;
> > +       bool cabc_en;
> > +};
> > +
> 
> Could this be further squashed to bellow structure?
> 

It could, but I see that it would simplify things.

> > +struct pm8941_wled {
> > +       struct regmap *regmap;
> > +       u16 addr;
> > +
> > +       struct led_classdev cdev;
> > +
> > +       struct pm8941_wled_config cfg;
> > +};
> > +
> > 
> 
> <snip>
> 
> > +static void pm8941_wled_set_brightness(struct led_classdev *cdev,
> > +                                                                                       enum 
> > led_brightness value)
> > +{
> > +       if (pm8941_wled_set(cdev, value)) {
> 
> pm8941_wled_set() is used only here, could it be merged into this function?
>  

It could, but that would just mean that we move these lines into the tail of
pm8941_wled_set and replace all the returns with a bunch of gotos. So I don't
think it's cleaner.

> > +               dev_err(cdev->dev, "Unable to set brightness\n");
> > +               return;
> > +       }
> > +       cdev->brightness = value;
> > +}
> > +
> > 
> 
> Otherwise it looks good. Driver is loaded and device is detected
> properly (i have added readings for type and subtype registers).
> Do you know where I can measure result from changing brightness 
> sysfs entry. I am using 8074 dragonboard?
> 

I'm not sure how this is exposed on the dragonboard. I've tested it on Xperia
Z1 (honami) and the display lights up nicely.

Regards,
Bjorn
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