Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Wed, Jul 29, 2015 at 6:51 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: On Fri 24 Jul 08:29 PDT 2015, Rob Herring wrote: On Thu, Jul 23, 2015 at 2:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. Well, we have default-brightness and default-brightness-level used by 1 driver each. But default-brightness-level is much more commonly used (in dts files) since it is in the pwm backlight binding, so we should go with it. I'd like to see this moved to a common backlight doc. As I looked at these, the default-brightness used in tps65217 is a value between 0 and 100, so that can be interpreted as a percentage. The pwm binding however uses a separate array of brightness-levels and then default-brightness-level is supposed to be an index into that array. Uggg. I missed that minor detail... As we're trying to specify a default brightness within the range [0, max_brightness) the latter doesn't make much sense. Therefor my suggestion is that we make the default-brightness the common property and we define it as a percentage of [0,max_brightness). Okay. I wonder if we should have units such as default-brightness-percentage or default-brightness-% so it is clear. Otherwise, we might have some people doing a range of [0,max]. The former is a bit long and the latter is a bit unusual. Really, I think all the backlight documentation should be merged with LEDs docs. Things like default-on are common. But I won't ask to do that here. I think the backlight framework should be merged with the LED framework. There's several hw blocks that are split between the two, with an mfd tying them together... Fully agree. BTW, doing that doesn't have to be in sync between the bindings and drivers. Of course, if we've designed the bindings with sub devices to fit the MFD structure, then that is another problem. Rob -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Thu 30 Jul 08:26 PDT 2015, Rob Herring wrote: On Wed, Jul 29, 2015 at 6:51 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: On Fri 24 Jul 08:29 PDT 2015, Rob Herring wrote: [..] As we're trying to specify a default brightness within the range [0, max_brightness) the latter doesn't make much sense. Therefor my suggestion is that we make the default-brightness the common property and we define it as a percentage of [0,max_brightness). Okay. I wonder if we should have units such as default-brightness-percentage or default-brightness-% so it is clear. Otherwise, we might have some people doing a range of [0,max]. The former is a bit long and the latter is a bit unusual. I discussed this further with my colleague and gave it some though over the night; If the boot loader sets the brightness, it would need to convert this to a percentage just to have the kernel convert it back - with a expected lack of precision (especially w/ non-linear brightness ranges or odd step-sizes). In the case where it's manually tweaked by the developer he/she would most likely modify the brightness through sysfs until a reasonable value is found; and we have that extra step again of converting this to a percentage. Therefor I think it's better to just specify this in units of brightness - which would be a unit-less property. Regards, Bjorn -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Fri 24 Jul 08:29 PDT 2015, Rob Herring wrote: On Thu, Jul 23, 2015 at 2:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. Well, we have default-brightness and default-brightness-level used by 1 driver each. But default-brightness-level is much more commonly used (in dts files) since it is in the pwm backlight binding, so we should go with it. I'd like to see this moved to a common backlight doc. As I looked at these, the default-brightness used in tps65217 is a value between 0 and 100, so that can be interpreted as a percentage. The pwm binding however uses a separate array of brightness-levels and then default-brightness-level is supposed to be an index into that array. As we're trying to specify a default brightness within the range [0, max_brightness) the latter doesn't make much sense. Therefor my suggestion is that we make the default-brightness the common property and we define it as a percentage of [0,max_brightness). Really, I think all the backlight documentation should be merged with LEDs docs. Things like default-on are common. But I won't ask to do that here. I think the backlight framework should be merged with the LED framework. There's several hw blocks that are split between the two, with an mfd tying them together... Regards, Bjorn -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Thu, 23 Jul 2015, Bjorn Andersson wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. [1] https://lkml.org/lkml/2015/7/21/906 Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt | 1 + This needs to be in a seperate patch. drivers/video/backlight/pm8941-wled.c | 4 You can't send patches on top of non-existent drivers. 2 files changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt index 424f8444a6cd..37503f8c3620 100644 --- a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt +++ b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt @@ -5,6 +5,7 @@ Required properties: - reg: slave address Optional properties: +- default-brightness: value from: 0-4095 - label: The name of the backlight device - qcom,cs-out: bool; enable current sink output - qcom,cabc: bool; enable content adaptive backlight control diff --git a/drivers/video/backlight/pm8941-wled.c b/drivers/video/backlight/pm8941-wled.c index c704c3236034..b875e58df0fc 100644 --- a/drivers/video/backlight/pm8941-wled.c +++ b/drivers/video/backlight/pm8941-wled.c @@ -373,6 +373,7 @@ static int pm8941_wled_probe(struct platform_device *pdev) struct backlight_device *bl; struct pm8941_wled *wled; struct regmap *regmap; + u32 val = 0; int rc; regmap = dev_get_regmap(pdev-dev.parent, NULL); @@ -395,8 +396,11 @@ static int pm8941_wled_probe(struct platform_device *pdev) if (rc) return rc; + of_property_read_u32(pdev-dev.of_node, default-brightness, val); + memset(props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; + props.brightness = val; props.max_brightness = PM8941_WLED_REG_VAL_MAX; bl = devm_backlight_device_register(pdev-dev, wled-name, pdev-dev, wled, -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Fri, Jul 24, 2015 at 8:10 AM, Rob Clark robdcl...@gmail.com wrote: On Thu, Jul 23, 2015 at 3:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. [1] https://lkml.org/lkml/2015/7/21/906 Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt | 1 + drivers/video/backlight/pm8941-wled.c | 4 2 files changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt index 424f8444a6cd..37503f8c3620 100644 --- a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt +++ b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt @@ -5,6 +5,7 @@ Required properties: - reg: slave address Optional properties: +- default-brightness: value from: 0-4095 - label: The name of the backlight device - qcom,cs-out: bool; enable current sink output - qcom,cabc: bool; enable content adaptive backlight control diff --git a/drivers/video/backlight/pm8941-wled.c b/drivers/video/backlight/pm8941-wled.c index c704c3236034..b875e58df0fc 100644 --- a/drivers/video/backlight/pm8941-wled.c +++ b/drivers/video/backlight/pm8941-wled.c @@ -373,6 +373,7 @@ static int pm8941_wled_probe(struct platform_device *pdev) struct backlight_device *bl; struct pm8941_wled *wled; struct regmap *regmap; + u32 val = 0; int rc; as discussed on IRC, it would be better if the default read back the current settings (so-as to inherit bootloader splash smoothly.. drm/msm supports a memory-region phandle, for example, so it can take over the bootloader splash-screen as stolen-mem) and it would I think be useful to have a comment in the bindings file explaining that you *should* use the default-brightness property to set a sane default if bootloader isn't putting up a splash, and you should *not* use the property if it is.. +1 What if you have neither? Set to max brightness? 75%? This could also be used for the bootloader to communicate to the kernel what the current level is if it is not readable. I've seen one backlight recently which you change the level by doing some number of pulses on a gpio and a long pulse to turn off. So there is no way to know current level without turning off the backlight (unless you hardcode the bootloader's level in the kernel like the vendor did). Rob -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Thu, Jul 23, 2015 at 2:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. Well, we have default-brightness and default-brightness-level used by 1 driver each. But default-brightness-level is much more commonly used (in dts files) since it is in the pwm backlight binding, so we should go with it. I'd like to see this moved to a common backlight doc. Really, I think all the backlight documentation should be merged with LEDs docs. Things like default-on are common. But I won't ask to do that here. Rob [1] https://lkml.org/lkml/2015/7/21/906 Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt | 1 + drivers/video/backlight/pm8941-wled.c | 4 2 files changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt index 424f8444a6cd..37503f8c3620 100644 --- a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt +++ b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt @@ -5,6 +5,7 @@ Required properties: - reg: slave address Optional properties: +- default-brightness: value from: 0-4095 - label: The name of the backlight device - qcom,cs-out: bool; enable current sink output - qcom,cabc: bool; enable content adaptive backlight control diff --git a/drivers/video/backlight/pm8941-wled.c b/drivers/video/backlight/pm8941-wled.c index c704c3236034..b875e58df0fc 100644 --- a/drivers/video/backlight/pm8941-wled.c +++ b/drivers/video/backlight/pm8941-wled.c @@ -373,6 +373,7 @@ static int pm8941_wled_probe(struct platform_device *pdev) struct backlight_device *bl; struct pm8941_wled *wled; struct regmap *regmap; + u32 val = 0; int rc; regmap = dev_get_regmap(pdev-dev.parent, NULL); @@ -395,8 +396,11 @@ static int pm8941_wled_probe(struct platform_device *pdev) if (rc) return rc; + of_property_read_u32(pdev-dev.of_node, default-brightness, val); + memset(props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; + props.brightness = val; props.max_brightness = PM8941_WLED_REG_VAL_MAX; bl = devm_backlight_device_register(pdev-dev, wled-name, pdev-dev, wled, -- 1.8.2.2 -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Fri, Jul 24, 2015 at 11:39 AM, Rob Herring robherri...@gmail.com wrote: On Fri, Jul 24, 2015 at 8:10 AM, Rob Clark robdcl...@gmail.com wrote: On Thu, Jul 23, 2015 at 3:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. [1] https://lkml.org/lkml/2015/7/21/906 Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt | 1 + drivers/video/backlight/pm8941-wled.c | 4 2 files changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt index 424f8444a6cd..37503f8c3620 100644 --- a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt +++ b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt @@ -5,6 +5,7 @@ Required properties: - reg: slave address Optional properties: +- default-brightness: value from: 0-4095 - label: The name of the backlight device - qcom,cs-out: bool; enable current sink output - qcom,cabc: bool; enable content adaptive backlight control diff --git a/drivers/video/backlight/pm8941-wled.c b/drivers/video/backlight/pm8941-wled.c index c704c3236034..b875e58df0fc 100644 --- a/drivers/video/backlight/pm8941-wled.c +++ b/drivers/video/backlight/pm8941-wled.c @@ -373,6 +373,7 @@ static int pm8941_wled_probe(struct platform_device *pdev) struct backlight_device *bl; struct pm8941_wled *wled; struct regmap *regmap; + u32 val = 0; int rc; as discussed on IRC, it would be better if the default read back the current settings (so-as to inherit bootloader splash smoothly.. drm/msm supports a memory-region phandle, for example, so it can take over the bootloader splash-screen as stolen-mem) and it would I think be useful to have a comment in the bindings file explaining that you *should* use the default-brightness property to set a sane default if bootloader isn't putting up a splash, and you should *not* use the property if it is.. +1 What if you have neither? Set to max brightness? 75%? I did chat w/ Bjorn a bit about that on irc.. his concern was some arbitrary percentage (like 50%) might be more or less bright depending on the device (although that implies to me that maybe we should have min and max bindings as well, rather than just assuming hw limits? idk) my preference is the default is somehow at least not 0%.. possibly motivated by the expectation that when people see a dark screen at boot they assume the display driver is broken :-P BR, -R This could also be used for the bootloader to communicate to the kernel what the current level is if it is not readable. I've seen one backlight recently which you change the level by doing some number of pulses on a gpio and a long pulse to turn off. So there is no way to know current level without turning off the backlight (unless you hardcode the bootloader's level in the kernel like the vendor did). Rob -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] backlight: pm8941-wled: Add default-brightness property
On Thu, Jul 23, 2015 at 3:52 PM, Bjorn Andersson bjorn.anders...@sonymobile.com wrote: Add the possibility of specifying the default brightness in DT. Signed-off-by: Bjorn Andersson bjorn.anders...@sonymobile.com --- This depends on the patch moving pm8941-wled to backlight [1]. The dt property is used by several other backlight drivers, so I considered this to be a common property and it's hence not prefixed with qcom,. [1] https://lkml.org/lkml/2015/7/21/906 Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt | 1 + drivers/video/backlight/pm8941-wled.c | 4 2 files changed, 5 insertions(+) diff --git a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt index 424f8444a6cd..37503f8c3620 100644 --- a/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt +++ b/Documentation/devicetree/bindings/video/backlight/pm8941-wled.txt @@ -5,6 +5,7 @@ Required properties: - reg: slave address Optional properties: +- default-brightness: value from: 0-4095 - label: The name of the backlight device - qcom,cs-out: bool; enable current sink output - qcom,cabc: bool; enable content adaptive backlight control diff --git a/drivers/video/backlight/pm8941-wled.c b/drivers/video/backlight/pm8941-wled.c index c704c3236034..b875e58df0fc 100644 --- a/drivers/video/backlight/pm8941-wled.c +++ b/drivers/video/backlight/pm8941-wled.c @@ -373,6 +373,7 @@ static int pm8941_wled_probe(struct platform_device *pdev) struct backlight_device *bl; struct pm8941_wled *wled; struct regmap *regmap; + u32 val = 0; int rc; as discussed on IRC, it would be better if the default read back the current settings (so-as to inherit bootloader splash smoothly.. drm/msm supports a memory-region phandle, for example, so it can take over the bootloader splash-screen as stolen-mem) and it would I think be useful to have a comment in the bindings file explaining that you *should* use the default-brightness property to set a sane default if bootloader isn't putting up a splash, and you should *not* use the property if it is.. BR, -R regmap = dev_get_regmap(pdev-dev.parent, NULL); @@ -395,8 +396,11 @@ static int pm8941_wled_probe(struct platform_device *pdev) if (rc) return rc; + of_property_read_u32(pdev-dev.of_node, default-brightness, val); + memset(props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; + props.brightness = val; props.max_brightness = PM8941_WLED_REG_VAL_MAX; bl = devm_backlight_device_register(pdev-dev, wled-name, pdev-dev, wled, -- 1.8.2.2 -- To unsubscribe from this list: send the line unsubscribe linux-arm-msm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
