[Outreachy kernel] [PATCH v13 2/3] drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c
Meghana Madhyastha
meghana.madhyastha at gmail.com
Wed Oct 18 17:11:34 UTC 2017
On Mon, Oct 16, 2017 at 02:26:00PM -0400, Sean Paul wrote:
> On Fri, Oct 13, 2017 at 6:42 PM, Noralf Trønnes <noralf at tronnes.org> wrote:
> >
> > Den 13.10.2017 22.25, skrev Sean Paul:
> >>
> >> On Fri, Oct 13, 2017 at 04:11:43PM +0530, Meghana Madhyastha wrote:
> >>>
> >>> Rename tinydrm_of_find_backlight to backlight_get and move it
> >>> to linux/backlight.c so that it can be used by other drivers.
> >>
> >> [apologies if this has been brought up in previous versions, I haven't
> >> been
> >> following closely]
> >>
> >> I don't think "backlight_get" is a good name for this function. How about
> >> of_find_backlight_by_name (since there's already
> >> of_find_backlight_by_node)?
> >
> >
> > I came up with that name modelled after gpiod_get() and gpiod_put() and I
> > deliberately kept the of_ part out of the name like the gpio functions.
> > gpiod_get() checks OF, ACPI and platform for gpios and calling it
> > backlight_get() would keep the door open for other ways of connecting
> > backlight devices in the future, other than Device Tree.
> >
>
> Thanks for the background, Noralf! Apologies for stepping on top of
> your previous reviews.
>
> > I think of_find_backlight() would be better than *_by_name(), since
> > 'backlight' is the common DT property name, so it wouldn't make much sense
> > to require every caller to pass in the same name.
> >
>
> of_find_backlight() sounds like a good compromise.
>
> Sean
Are there any changes that need to be made to this patchset now ?
Regards,
Meghana
>
> > Either way is fine with me.
> >
> > Noralf.
> >
> >
> >
> >>> Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
> >>> ---
> >>> Changes in v13:
> >>> -Add backlight_put to backlight.h in this patch
> >>>
> >>> drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 40
> >>> --------------------------
> >>> drivers/gpu/drm/tinydrm/mi0283qt.c | 3 +-
> >>> drivers/video/backlight/backlight.c | 37
> >>> ++++++++++++++++++++++++
> >>> include/drm/tinydrm/tinydrm-helpers.h | 2 --
> >>> include/linux/backlight.h | 19 ++++++++++++
> >>> 5 files changed, 58 insertions(+), 43 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> >>> b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> >>> index a42dee6..cb1a01a 100644
> >>> --- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> >>> +++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> >>> @@ -236,46 +236,6 @@ void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr,
> >>> struct drm_framebuffer *fb,
> >>> }
> >>> EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);
> >>> -/**
> >>> - * tinydrm_of_find_backlight - Find backlight device in device-tree
> >>> - * @dev: Device
> >>> - *
> >>> - * This function looks for a DT node pointed to by a property named
> >>> 'backlight'
> >>> - * and uses of_find_backlight_by_node() to get the backlight device.
> >>> - * Additionally if the brightness property is zero, it is set to
> >>> - * max_brightness.
> >>> - *
> >>> - * Returns:
> >>> - * NULL if there's no backlight property.
> >>> - * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight
> >>> device
> >>> - * is found.
> >>> - * If the backlight device is found, a pointer to the structure is
> >>> returned.
> >>> - */
> >>> -struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
> >>> -{
> >>> - struct backlight_device *backlight;
> >>> - struct device_node *np;
> >>> -
> >>> - np = of_parse_phandle(dev->of_node, "backlight", 0);
> >>> - if (!np)
> >>> - return NULL;
> >>> -
> >>> - backlight = of_find_backlight_by_node(np);
> >>> - of_node_put(np);
> >>> -
> >>> - if (!backlight)
> >>> - return ERR_PTR(-EPROBE_DEFER);
> >>> -
> >>> - if (!backlight->props.brightness) {
> >>> - backlight->props.brightness =
> >>> backlight->props.max_brightness;
> >>> - DRM_DEBUG_KMS("Backlight brightness set to %d\n",
> >>> - backlight->props.brightness);
> >>> - }
> >>> -
> >>> - return backlight;
> >>> -}
> >>> -EXPORT_SYMBOL(tinydrm_of_find_backlight);
> >>> -
> >>> #if IS_ENABLED(CONFIG_SPI)
> >>> /**
> >>> diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c
> >>> b/drivers/gpu/drm/tinydrm/mi0283qt.c
> >>> index 7fd2691..a932185 100644
> >>> --- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> >>> +++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> >>> @@ -12,6 +12,7 @@
> >>> #include <drm/tinydrm/ili9341.h>
> >>> #include <drm/tinydrm/mipi-dbi.h>
> >>> #include <drm/tinydrm/tinydrm-helpers.h>
> >>> +#include <linux/backlight.h>
> >>> #include <linux/delay.h>
> >>> #include <linux/gpio/consumer.h>
> >>> #include <linux/module.h>
> >>> @@ -188,7 +189,7 @@ static int mi0283qt_probe(struct spi_device *spi)
> >>> if (IS_ERR(mipi->regulator))
> >>> return PTR_ERR(mipi->regulator);
> >>> - mipi->backlight = tinydrm_of_find_backlight(dev);
> >>> + mipi->backlight = backlight_get(dev);
> >>> if (IS_ERR(mipi->backlight))
> >>> return PTR_ERR(mipi->backlight);
> >>> diff --git a/drivers/video/backlight/backlight.c
> >>> b/drivers/video/backlight/backlight.c
> >>> index 8049e76..c4e94d0 100644
> >>> --- a/drivers/video/backlight/backlight.c
> >>> +++ b/drivers/video/backlight/backlight.c
> >>> @@ -580,6 +580,43 @@ struct backlight_device
> >>> *of_find_backlight_by_node(struct device_node *node)
> >>> EXPORT_SYMBOL(of_find_backlight_by_node);
> >>> #endif
> >>> +/**
> >>> + * backlight_get - Get backlight device
> >>> + * @dev: Device
> >>> + *
> >>> + * This function looks for a property named 'backlight' on the DT node
> >>> + * connected to @dev and looks up the backlight device.
> >>> + *
> >>> + * Call backlight_put() to drop the reference on the backlight device.
> >>> + *
> >>> + * Returns:
> >>> + * A pointer to the backlight device if found.
> >>> + * Error pointer -EPROBE_DEFER if the DT property is set, but no
> >>> backlight
> >>> + * device is found.
> >>> + * NULL if there's no backlight property.
> >>> + */
> >>> +struct backlight_device *backlight_get(struct device *dev)
> >>> +{
> >>> + struct backlight_device *bd = NULL;
> >>> + struct device_node *np;
> >>> +
> >>> + if (!dev)
> >>> + return NULL;
> >>> +
> >>> + if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> >>
> >> I'm not really used to seeing IS_ENABLED(CONFIG_BLAH) inline. The common
> >> patterns seems to be wrapping the actual implementation in #if
> >> IS_ENABLED(CONFIG_BLAH) and then sticking a stub implementation in the
> >> #else.
> >>
> >> I see below that you already have a stub if backlight is not enabled, so
> >> expand
> >> that #if to include CONFIG_OF as well.
> >>
> >>> + np = of_parse_phandle(dev->of_node, "backlight", 0);
> >>> + if (np) {
> >>> + bd = of_find_backlight_by_node(np);
> >>> + of_node_put(np);
> >>> + if (!bd)
> >>> + return ERR_PTR(-EPROBE_DEFER);
> >>> + }
> >>> + }
> >>> +
> >>> + return bd;
> >>> +}
> >>> +EXPORT_SYMBOL(backlight_get);
> >>> +
> >>> static void __exit backlight_class_exit(void)
> >>> {
> >>> class_destroy(backlight_class);
> >>> diff --git a/include/drm/tinydrm/tinydrm-helpers.h
> >>> b/include/drm/tinydrm/tinydrm-helpers.h
> >>> index f54fae0..0a4ddbc 100644
> >>> --- a/include/drm/tinydrm/tinydrm-helpers.h
> >>> +++ b/include/drm/tinydrm/tinydrm-helpers.h
> >>> @@ -46,8 +46,6 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
> >>> void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct
> >>> drm_framebuffer *fb,
> >>> struct drm_clip_rect *clip);
> >>> -struct backlight_device *tinydrm_of_find_backlight(struct device
> >>> *dev);
> >>> -
> >>> size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t
> >>> max_len);
> >>> bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
> >>> int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
> >>> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> >>> index b88fabb..987a6d7 100644
> >>> --- a/include/linux/backlight.h
> >>> +++ b/include/linux/backlight.h
> >>> @@ -159,6 +159,16 @@ static inline int backlight_disable(struct
> >>> backlight_device *bd)
> >>> return backlight_update_status(bd);
> >>> }
> >>> +/**
> >>> + * backlight_put - Drop backlight reference
> >>> + * @bd: the backlight device to put
> >>> + */
> >>> +static inline void backlight_put(struct backlight_device *bd)
> >>> +{
> >>> + if (bd)
> >>> + put_device(&bd->dev);
> >>> +}
> >>
> >> I'm not convinced this function needs to exist.
> >>
> >>> +
> >>> extern struct backlight_device *backlight_device_register(const char
> >>> *name,
> >>> struct device *dev, void *devdata, const struct backlight_ops
> >>> *ops,
> >>> const struct backlight_properties *props);
> >>> @@ -202,4 +212,13 @@ of_find_backlight_by_node(struct device_node *node)
> >>> }
> >>> #endif
> >>> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
> >>> +struct backlight_device *backlight_get(struct device *dev);
> >>> +#else
> >>> +static inline struct backlight_device *backlight_get(struct device *dev)
> >>> +{
> >>> + return NULL;
> >>> +}
> >>> +#endif
> >>> +
> >>> #endif
> >>> --
> >>> 2.7.4
> >>>
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