From: Jean-Jacques Hiblot <jjhiblot@ti.com> To: Pavel Machek <pavel@ucw.cz> Cc: mark.rutland@arm.com, Daniel Thompson <daniel.thompson@linaro.org>, jingoohan1@gmail.com, tomi.valkeinen@ti.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, robh+dt@kernel.org, jacek.anaszewski@gmail.com, lee.jones@linaro.org, linux-leds@vger.kernel.org, dmurphy@ti.com Subject: Re: [PATCH 3/4] backlight: add led-backlight driver Date: Fri, 5 Jul 2019 12:33:33 +0200 [thread overview] Message-ID: <6c21af33-8c3b-58a8-0a1b-f85fb9f80050@ti.com> (raw) In-Reply-To: <20190705100851.zn2jkipj4fxq5we6@devuan> Pavel On 05/07/2019 12:08, Pavel Machek wrote: > Hi! > >>>>> Also still relevant is whether the LED device is being correctly >>>>> modelled if the act of turning on the LED doesn't, in fact, turn the LED >>>>> on. Is it *really* a correct implementation of an LED device that >>>>> setting it to LED_FULL using sysfs doesn't cause it to light up? >>>> What I understood from the discussion between Rob and Tomi is that the >>>> child-node of the LED controller should be considered a backlight device, >>>> not a simple LED. I'm not sure if the sysfs interface is still relevant in >>>> that case. Maybe it should just be disabled by the backlight driver >>>> (possible with led_sysfs_disable()) >>> led_sysfs_disable() sounds like a sensible change but that's not quite >>> what I mean. >>> >>> It is more a thought experiment to see if the power control *should* be >>> implemented by the backlight. Consider what happens if we *don't* >>> enable CONFIG_BACKLIGHT_LED in the kernel: we would still have an LED >>> device and it would not work correctly. >>> >>> In other words I naively expect turning on an LED using the LED API >>> (any of them, sysfs or kernel) to result in the LED turning on. >>> Implementing a workaround in the client for what appears to be >>> something missing in the LED driver strikes me as odd. Why shouldn't >>> the regulator be managed in the LED driver? >> I see your point. Indeed having the regulator handled in the LED-core makes >> sense in a lot of situations >> >> I'll think about it. > For the record, I also believe regulator and enable gpio should be > handled in the core. I am working on adding the regulator to the led core. I don't really want to add a GPIO enable to the core though. If needed it can be described as a GPIO-enabled regulator up(/down)stream the regular regulator. JJ > > Pavel > PS please trim down the quoted text. _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
WARNING: multiple messages have this Message-ID (diff)
From: Jean-Jacques Hiblot <jjhiblot@ti.com> To: Pavel Machek <pavel@ucw.cz> Cc: Daniel Thompson <daniel.thompson@linaro.org>, <jacek.anaszewski@gmail.com>, <robh+dt@kernel.org>, <mark.rutland@arm.com>, <lee.jones@linaro.org>, <jingoohan1@gmail.com>, <dmurphy@ti.com>, <linux-leds@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <dri-devel@lists.freedesktop.org>, <tomi.valkeinen@ti.com> Subject: Re: [PATCH 3/4] backlight: add led-backlight driver Date: Fri, 5 Jul 2019 12:33:33 +0200 [thread overview] Message-ID: <6c21af33-8c3b-58a8-0a1b-f85fb9f80050@ti.com> (raw) Message-ID: <20190705103333.r1GDsOwRttBnf_7ka0oy0l5QtUXEeKwfQ9RCD0lU4-M@z> (raw) In-Reply-To: <20190705100851.zn2jkipj4fxq5we6@devuan> Pavel On 05/07/2019 12:08, Pavel Machek wrote: > Hi! > >>>>> Also still relevant is whether the LED device is being correctly >>>>> modelled if the act of turning on the LED doesn't, in fact, turn the LED >>>>> on. Is it *really* a correct implementation of an LED device that >>>>> setting it to LED_FULL using sysfs doesn't cause it to light up? >>>> What I understood from the discussion between Rob and Tomi is that the >>>> child-node of the LED controller should be considered a backlight device, >>>> not a simple LED. I'm not sure if the sysfs interface is still relevant in >>>> that case. Maybe it should just be disabled by the backlight driver >>>> (possible with led_sysfs_disable()) >>> led_sysfs_disable() sounds like a sensible change but that's not quite >>> what I mean. >>> >>> It is more a thought experiment to see if the power control *should* be >>> implemented by the backlight. Consider what happens if we *don't* >>> enable CONFIG_BACKLIGHT_LED in the kernel: we would still have an LED >>> device and it would not work correctly. >>> >>> In other words I naively expect turning on an LED using the LED API >>> (any of them, sysfs or kernel) to result in the LED turning on. >>> Implementing a workaround in the client for what appears to be >>> something missing in the LED driver strikes me as odd. Why shouldn't >>> the regulator be managed in the LED driver? >> I see your point. Indeed having the regulator handled in the LED-core makes >> sense in a lot of situations >> >> I'll think about it. > For the record, I also believe regulator and enable gpio should be > handled in the core. I am working on adding the regulator to the led core. I don't really want to add a GPIO enable to the core though. If needed it can be described as a GPIO-enabled regulator up(/down)stream the regular regulator. JJ > > Pavel > PS please trim down the quoted text.
next prev parent reply other threads:[~2019-07-05 10:33 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-01 15:14 [PATCH 0/4] Add a generic driver for LED-based backlight Jean-Jacques Hiblot 2019-07-01 15:14 ` [PATCH 1/4] leds: of: create a child device if the LED node contains a "compatible" string Jean-Jacques Hiblot 2019-07-01 15:14 ` [PATCH 2/4] devicetree: Update led binding Jean-Jacques Hiblot 2019-07-01 15:20 ` Dan Murphy 2019-07-01 15:14 ` [PATCH 3/4] backlight: add led-backlight driver Jean-Jacques Hiblot 2019-07-02 9:54 ` Daniel Thompson 2019-07-02 10:59 ` Jean-Jacques Hiblot 2019-07-02 13:04 ` Daniel Thompson 2019-07-02 15:17 ` Jean-Jacques Hiblot 2019-07-03 9:44 ` Daniel Thompson 2019-07-03 10:02 ` Jean-Jacques Hiblot 2019-07-05 10:08 ` Pavel Machek 2019-07-05 10:08 ` Pavel Machek 2019-07-05 10:33 ` Jean-Jacques Hiblot [this message] 2019-07-05 10:33 ` Jean-Jacques Hiblot 2019-07-01 15:14 ` [PATCH 4/4] devicetree: Add led-backlight binding Jean-Jacques Hiblot 2019-07-02 9:58 ` Daniel Thompson 2019-07-02 11:11 ` Jean-Jacques Hiblot 2019-07-05 10:11 ` Pavel Machek 2019-07-05 10:11 ` Pavel Machek 2019-07-05 10:14 ` [PATCH 0/4] Add a generic driver for LED-based backlight Pavel Machek 2019-07-05 10:14 ` Pavel Machek 2019-07-05 10:29 ` Daniel Thompson 2019-07-05 10:29 ` Daniel Thompson 2019-07-05 11:34 ` Jean-Jacques Hiblot 2019-07-05 11:34 ` Jean-Jacques Hiblot 2019-07-05 23:23 ` Sebastian Reichel 2019-07-05 23:23 ` Sebastian Reichel
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