On Thu, Sep 28, 2017 at 06:02:27PM +0200, Noralf Trønnes wrote:
>
> Den 28.09.2017 16.08, skrev Daniel Vetter:
> > On Thu, Sep 28, 2017 at 02:44:34PM +0530, Meghana Madhyastha wrote:
> > > Rename tinydrm_of_find_backlight to drm_of_find_backlight
> > > and move it into drm_of.c from tinydrm-helpers.c. This is
> > > because other drivers in the drm subsystem might need to call
> > > this function. In that case and otherwise, it is better from
> > > an organizational point of view to move it into drm_of.c along
> > > with the other _of.c functions.
> > >
> > > Signed-off-by: Meghana Madhyastha <meghana.madhyastha@xxxxxxxxx>
> > > ---
> > > Changes in v3:
> > > -Change it back to a single patch from two patches in v2
> > >
> > > drivers/gpu/drm/drm_of.c | 44 ++++++++++++++++++++++++++
> > > drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 40 -----------------------
> > > drivers/gpu/drm/tinydrm/mi0283qt.c | 3 +-
> > > include/drm/drm_of.h | 1 +
> > > include/drm/tinydrm/tinydrm-helpers.h | 1 -
> > > 5 files changed, 47 insertions(+), 42 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
> > > index 8dafbdf..d878d3a 100644
> > > --- a/drivers/gpu/drm/drm_of.c
> > > +++ b/drivers/gpu/drm/drm_of.c
> > > @@ -1,6 +1,7 @@
> > > #include <linux/component.h>
> > > #include <linux/export.h>
> > > #include <linux/list.h>
> > > +#include <linux/backlight.h>
> > > #include <linux/of_graph.h>
> > > #include <drm/drmP.h>
> > > #include <drm/drm_bridge.h>
> > > @@ -260,3 +261,46 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
> > > return ret;
> > > }
> > > EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);
> > > +
> > > +/**
> > > + * drm_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.
> > > + *
> > > + * Note: It is the responsibility of the caller to call put_device() when
> > > + * releasing the resource.
> > > + *
> > > + * 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 *drm_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(drm_of_find_backlight);
> > > diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > index bd6cce0..cd4c6a5 100644
> > > --- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > +++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > @@ -237,46 +237,6 @@ 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);
> > > -
> > > -/**
> > > * tinydrm_enable_backlight - Enable backlight helper
> > > * @backlight: Backlight device
> > > *
> > > diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
> > > index 7e5bb7d..5e3d635 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 <drm/drm_of.h>
> > > #include <linux/delay.h>
> > > #include <linux/gpio/consumer.h>
> > > #include <linux/module.h>
> > > @@ -189,7 +190,7 @@ 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 = drm_of_find_backlight(dev);
> > > if (IS_ERR(mipi->backlight))
> > > return PTR_ERR(mipi->backlight);
> > > diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
> > > index 104dd51..e8fba5b 100644
> > > --- a/include/drm/drm_of.h
> > > +++ b/include/drm/drm_of.h
> > > @@ -29,6 +29,7 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
> > > int port, int endpoint,
> > > struct drm_panel **panel,
> > > struct drm_bridge **bridge);
> > > +struct backlight_device *drm_of_find_backlight(struct device *dev);
> > > #else
> > > static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
> > > struct device_node *port)
> > Minor detail I missed: The dummy version for the #else here is missing.
> > Not a problem for tinydrm, but might be an issue for a driver where
> > CONFIG_OF is optional.
>
> Yeah, we need a dummy version. tinydrm can in theory be used on non-DT
> platforms. The only resource that isn't available there is backlight
> since there is no platform or ACPI way of describing that dependency.
>
> Another problem I discovered when trying to compile this, is that if
> DRM is builtin and LCD_CLASS_DEVICE is a module:
>
> drivers/gpu/drm/drm_of.c:292: undefined reference to
> `of_find_backlight_by_node'
>
> I see that I solved this in tinydrm by just selecting
> BACKLIGHT_LCD_SUPPORT and LCD_CLASS_DEVICE. I'm not aware of a way to
> force LCD_CLASS_DEVICE to be builtin if DRM is builtin.
The usual way to force such an optional depency is
depends on (FOO || FOO=n)
That way it's still optional, but if FOO is enabled as a module, you can't
enable the current symbol as built-in. See e.g. how DRM vs. AGP is
handled.
-Daniel
>
> Arnd fixed a similar type of dependecy in the repaper driver by forcing
> repaper to be a module if necessary. To be honest, I don't know why his
> fix works:
> https://github.com/torvalds/linux/commit/8312a3fe84b96e30a010fa20f933606d976ac002
>
> Another way of solving this is to put the function in
> drivers/gpu/drm/drm_backlight.c and add a DRM_BACKLIGHT konfig option
> that does the selection.
>
> Noralf.
>
> > Otherwise I think this patch looks good.
> > -Daniel
> >
> > > diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
> > > index d554ded..e40ef2d 100644
> > > --- a/include/drm/tinydrm/tinydrm-helpers.h
> > > +++ b/include/drm/tinydrm/tinydrm-helpers.h
> > > @@ -46,7 +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);
> > > int tinydrm_enable_backlight(struct backlight_device *backlight);
> > > int tinydrm_disable_backlight(struct backlight_device *backlight);
> > > --
> > > 2.7.4
> > >
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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