On Fri, Sep 29, 2017 at 02:33:12PM +0200, Noralf Trønnes wrote:
>
> Den 29.09.2017 14.20, skrev Meghana Madhyastha:
> >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.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.
> >>>>
> >>>>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.
>
> What's the error?
> Could this have something to do with tinydrm selecting backlight and
> depending on DRM?
>
> Noralf.
Looks like a case of circular dependencies. The exact error is this:
scripts/kconfig/mconf Kconfig
drivers/gpu/drm/Kconfig:7:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:7: symbol DRM depends on LCD_CLASS_DEVICE
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/backlight/Kconfig:16: symbol LCD_CLASS_DEVICE is
selected by FB_CLPS711X
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:338: symbol FB_CLPS711X depends on FB
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:5: symbol FB is selected by
DRM_KMS_FB_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:73: symbol DRM_KMS_FB_HELPER is selected by
DRM_FBDEV_EMULATION
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:90: symbol DRM_FBDEV_EMULATION depends on
DRM
Long story short, the dependency loop is as follows:
DRM -> LCD_CLASS_DEVICE -> FB_CLPS711X -> FB -> DRM_KMS_FB_HELPER ->
DRM_FBDEV_EMULATION -> DRM
Regards,
Meghana
> >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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