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Message-ID: <20190613103319.xhnb3vkjanycfqth@holly.lan>
Date: Thu, 13 Jun 2019 11:33:19 +0100
From: Daniel Thompson <daniel.thompson@...aro.org>
To: Shobhit Kukreti <shobhitkukreti@...il.com>
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 08:24:34AM -0700, Shobhit Kukreti wrote:
> 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.
Blind bug fixes are not prohibited by any means. However a clean up
without no (intentional) functional changes will certainly attract much
closer review and might also need more care when constructing a Cc: list
for the patch (e.g. to include the original author for their review or
testing, etc).
Daniel.
>
> >
> > > ---
> > > 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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