[PATCH v3 1/2] drm/tinydrm: Move tinydrm_of_find_backlight into drm_of.c
Noralf Trønnes
noralf at tronnes.org
Fri Sep 29 12:10:31 UTC 2017
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 at 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)
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.
>> 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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