On Fri, Sep 29, 2017 at 02:10:31PM +0200, Noralf Trønnes wrote:
>
> Den 29.09.2017 05.22, skrev Meghana Madhyastha:
> >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.madhyas...@gmail.com>
> >>>>---
> >>>>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.
> >>
> >>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
> >I didn't quite understand how we could use this fix for the current
> >case. Isn't this specific to the repaper driver dependency ?
>
> This is the solution Daniel mentions:
>
> menuconfig DRM
> tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI
> support)"
> depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
> + depends on (LCD_CLASS_DEVICE || LCD_CLASS_DEVICE=n)
I had tried this but it resulted in a recursive dependencies error.
Regards,
Meghana
>
> We also have another problem: CONFIG_OF=y && CONFIG_LCD_CLASS_DEVICE=n
> That will result in a missing symbol error.
>
> You can try this change to include/linux/backlight.h:
>
> -#ifdef CONFIG_OF
> +#if defined(CONFIG_OF) && IS_ENABLED(CONFIG_LCD_CLASS_DEVICE)
> struct backlight_device *of_find_backlight_by_node(struct device_node
> *node);
> #else
> static inline struct backlight_device *
> of_find_backlight_by_node(struct device_node *node)
> {
> return NULL;
> }
> #endif
>
> This will need to be a patch of its own since it's another subsystem.
>
> You have to try the various kconfig variations to be sure, I'm no kconfig
> expert.
> CONFIG_OF=y/n, CONFIG_DRM=y/m, CONFIG_LCD_CLASS_DEVICE=y/m/n
>
> Noralf.
Sure will try this.
> >>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
> >>>>
>
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