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Message-ID: <20190612152433.GA24293@t-1000>
Date: Wed, 12 Jun 2019 08:24:34 -0700
From: Shobhit Kukreti <shobhitkukreti@...il.com>
To: Daniel Thompson <daniel.thompson@...aro.org>
Cc: Lee Jones <lee.jones@...aro.org>,
Jingoo Han <jingoohan1@...il.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] video: backlight: Replace old GPIO APIs with GPIO
Consumer APIs for sky81542-backlight driver
On Wed, Jun 12, 2019 at 11:26:15AM +0100, Daniel Thompson wrote:
> Hi Shobhit
>
> Thanks for the patch. Feedback below...
Hi Daneil,
You provided some valuable feedback. Thank you for your time and
effort.
>
>
> On Tue, Jun 11, 2019 at 09:32:32PM -0700, Shobhit Kukreti wrote:
> > Port the sky81452-backlight driver to adhere to new gpio descriptor based
> > APIs. Modified the file sky81452-backlight.c and sky81452-backlight.h.
> > The gpio descriptor property in device tree should be "sky81452-en-gpios"
>
> That is contradicted by the device tree bindings. The property should
> remain "gpios" as it was before this conversion.
You are correct.
>
>
> > Removed unnecessary header files "linux/gpio.h" and "linux/of_gpio.h".
> >
> > Signed-off-by: Shobhit Kukreti <shobhitkukreti@...il.com>
>
> What level of testing have you done? Is this a fix for hardware you own
> or a cleanup after searching the sources?
>
I did not the test on actual hardware. I was trying to do a clean up and boot on
QEMU/rock960 board. I will drop the patch until I can find the sk81452
hardware to test it.
>
> > ---
> > drivers/video/backlight/sky81452-backlight.c | 24 ++++++++++++------------
> > include/linux/platform_data/sky81452-backlight.h | 4 +++-
> > 2 files changed, 15 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-backlight.c
> > index d414c7a..12ef628 100644
> > --- a/drivers/video/backlight/sky81452-backlight.c
> > +++ b/drivers/video/backlight/sky81452-backlight.c
> > @@ -19,12 +19,10 @@
> >
> > #include <linux/backlight.h>
> > #include <linux/err.h>
> > -#include <linux/gpio.h>
> > #include <linux/init.h>
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > #include <linux/of.h>
> > -#include <linux/of_gpio.h>
> > #include <linux/platform_device.h>
> > #include <linux/regmap.h>
> > #include <linux/platform_data/sky81452-backlight.h>
> > @@ -193,7 +191,6 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
> > pdata->ignore_pwm = of_property_read_bool(np, "skyworks,ignore-pwm");
> > pdata->dpwm_mode = of_property_read_bool(np, "skyworks,dpwm-mode");
> > pdata->phase_shift = of_property_read_bool(np, "skyworks,phase-shift");
> > - pdata->gpio_enable = of_get_gpio(np, 0);
> >
> > ret = of_property_count_u32_elems(np, "led-sources");
> > if (ret < 0) {
> > @@ -274,13 +271,17 @@ static int sky81452_bl_probe(struct platform_device *pdev)
> > if (IS_ERR(pdata))
> > return PTR_ERR(pdata);
> > }
> > -
> > - if (gpio_is_valid(pdata->gpio_enable)) {
> > - ret = devm_gpio_request_one(dev, pdata->gpio_enable,
> > - GPIOF_OUT_INIT_HIGH, "sky81452-en");
> > - if (ret < 0) {
> > - dev_err(dev, "failed to request GPIO. err=%d\n", ret);
> > - return ret;
> > + pdata->gpiod_enable = devm_gpiod_get(dev, "sk81452-en", GPIOD_OUT_HIGH);
>
> As above... I think the second argument here needs to be NULL in order
> to preserve the current DT bindings.
You are correct. I was testing this driver with a custom dtb in rock960 board and named
the property as above in the dts. It should be NULL.
>
> > + if (IS_ERR(pdata->gpiod_enable)) {
> > + long ret = PTR_ERR(pdata->gpiod_enable);
> > +
> > + /**
>
> Nitpicking... but no second star here. That's a trigger symbold for
> documentation processors.
That is a great feedback. I will keep that in mind.
>
> > + * gpiod_enable is optional in device tree.
> > + * Return error only if gpio was assigned in device tree
>
> Also nitpicking but I had to read this a few times because
> gpiod_enable is not in device tree, gpios is.
You are correct. I will make necessary changes.
>
> This is a common pattern so the comment can be very short. Something
> like:
>
> This DT property is optional so no need to propagate ENOENT
Noted.
>
>
> > + */
> > + if (ret != -ENOENT) {
> > + dev_err(dev, "failed to request GPIO. err=%ld\n", ret);
> > + return PTR_ERR(pdata->gpiod_enable);
> > }
> > }
> >
> > @@ -323,8 +324,7 @@ static int sky81452_bl_remove(struct platform_device *pdev)
> > bd->props.brightness = 0;
> > backlight_update_status(bd);
> >
> > - if (gpio_is_valid(pdata->gpio_enable))
> > - gpio_set_value_cansleep(pdata->gpio_enable, 0);
> > + gpiod_set_value_cansleep(pdata->gpiod_enable, 0);
> >
> > return 0;
> > }
> > diff --git a/include/linux/platform_data/sky81452-backlight.h b/include/linux/platform_data/sky81452-backlight.h
> > index 1231e9b..dc4cb85 100644
> > --- a/include/linux/platform_data/sky81452-backlight.h
> > +++ b/include/linux/platform_data/sky81452-backlight.h
> > @@ -20,6 +20,8 @@
> > #ifndef _SKY81452_BACKLIGHT_H
> > #define _SKY81452_BACKLIGHT_H
> >
> > +#include <linux/gpio/consumer.h>
> > +
>
> This heaer file should be included from the C file... it is not required
> to parse the header.
I appreciate the feedback. I will keep that in mind to avoid future
errors.
>
>
> Daniel.
>
>
> > /**
> > * struct sky81452_platform_data
> > * @name: backlight driver name.
> > @@ -34,7 +36,7 @@
> > */
> > struct sky81452_bl_platform_data {
> > const char *name;
> > - int gpio_enable;
> > + struct gpio_desc *gpiod_enable;
> > unsigned int enable;
> > bool ignore_pwm;
> > bool dpwm_mode;
> > --
> > 2.7.4
> >
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