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From: Matthias Kaehlcke <mka@chromium.org>
To: Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jingoo Han <jingoohan1@gmail.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Douglas Anderson <dianders@chromium.org>,
	Brian Norris <briannorris@chromium.org>,
	Pavel Machek <pavel@ucw.cz>,
	Jacek Anaszewski <jacek.anaszewski@gmail.com>
Subject: Re: [PATCH v3 2/4] backlight: Expose brightness curve type through sysfs
Date: Wed, 7 Aug 2019 13:15:28 -0700	[thread overview]
Message-ID: <20190807201528.GO250418@google.com> (raw)
In-Reply-To: <20190709190007.91260-3-mka@chromium.org>

On Tue, Jul 09, 2019 at 12:00:05PM -0700, Matthias Kaehlcke wrote:
> Backlight brightness curves can have different shapes. The two main
> types are linear and non-linear curves. The human eye doesn't
> perceive linearly increasing/decreasing brightness as linear (see
> also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED
> linearly to human eye"), hence many backlights use non-linear (often
> logarithmic) brightness curves. The type of curve currently is opaque
> to userspace, so userspace often uses more or less reliable heuristics
> (like the number of brightness levels) to decide whether to treat a
> backlight device as linear or non-linear.
> 
> Export the type of the brightness curve via the new sysfs attribute
> 'scale'. The value of the attribute can be 'linear', 'non-linear' or
> 'unknown'. For devices that don't provide information about the scale
> of their brightness curve the value of the 'scale' attribute is 'unknown'.
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

Daniel (et al): do you have any more comments on this patch/series or
is it ready to land?

Thanks

Matthias

WARNING: multiple messages have this Message-ID (diff)
From: Matthias Kaehlcke <mka@chromium.org>
To: Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Daniel Thompson <daniel.thompson@linaro.org>,
	Jingoo Han <jingoohan1@gmail.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Douglas Anderson <dianders@chromium.org>,
	Brian Norris <briannorris@chromium.org>,
	Pavel Machek <pavel@ucw.cz>,
	Jacek Anaszewski <jacek.anaszewski@gmail.com>
Subject: Re: [PATCH v3 2/4] backlight: Expose brightness curve type through sysfs
Date: Wed, 07 Aug 2019 20:15:28 +0000	[thread overview]
Message-ID: <20190807201528.GO250418@google.com> (raw)
In-Reply-To: <20190709190007.91260-3-mka@chromium.org>

On Tue, Jul 09, 2019 at 12:00:05PM -0700, Matthias Kaehlcke wrote:
> Backlight brightness curves can have different shapes. The two main
> types are linear and non-linear curves. The human eye doesn't
> perceive linearly increasing/decreasing brightness as linear (see
> also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED
> linearly to human eye"), hence many backlights use non-linear (often
> logarithmic) brightness curves. The type of curve currently is opaque
> to userspace, so userspace often uses more or less reliable heuristics
> (like the number of brightness levels) to decide whether to treat a
> backlight device as linear or non-linear.
> 
> Export the type of the brightness curve via the new sysfs attribute
> 'scale'. The value of the attribute can be 'linear', 'non-linear' or
> 'unknown'. For devices that don't provide information about the scale
> of their brightness curve the value of the 'scale' attribute is 'unknown'.
> 
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

Daniel (et al): do you have any more comments on this patch/series or
is it ready to land?

Thanks

Matthias

  reply	other threads:[~2019-08-07 20:15 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-09 19:00 [PATCH v3 0/4] backlight: Expose brightness curve type through sysfs Matthias Kaehlcke
2019-07-09 19:00 ` Matthias Kaehlcke
2019-07-09 19:00 ` [PATCH v3 1/4] MAINTAINERS: Add entry for stable backlight sysfs ABI documentation Matthias Kaehlcke
2019-07-09 19:00   ` Matthias Kaehlcke
2019-09-02  9:41   ` Lee Jones
2019-09-02  9:41     ` Lee Jones
2019-09-02  9:41     ` Lee Jones
2019-07-09 19:00 ` [PATCH v3 2/4] backlight: Expose brightness curve type through sysfs Matthias Kaehlcke
2019-07-09 19:00   ` Matthias Kaehlcke
2019-07-09 19:00   ` Matthias Kaehlcke
2019-08-07 20:15   ` Matthias Kaehlcke [this message]
2019-08-07 20:15     ` Matthias Kaehlcke
2019-08-16 15:54     ` Daniel Thompson
2019-08-16 15:54       ` Daniel Thompson
2019-08-16 17:53       ` Matthias Kaehlcke
2019-08-16 17:53         ` Matthias Kaehlcke
2019-08-19 10:02         ` Daniel Thompson
2019-08-19 10:02           ` Daniel Thompson
2019-08-19 18:50           ` Matthias Kaehlcke
2019-08-19 18:50             ` Matthias Kaehlcke
2019-08-19 18:50             ` Matthias Kaehlcke
2019-08-20 13:56             ` Daniel Thompson
2019-08-20 13:56               ` Daniel Thompson
2019-08-27  9:44               ` Lee Jones
2019-08-27  9:44                 ` Lee Jones
2019-08-29 14:09                 ` Daniel Thompson
2019-08-29 14:09                   ` Daniel Thompson
2019-08-16 16:51   ` Uwe Kleine-König
2019-08-16 16:51     ` Uwe Kleine-König
2019-08-16 17:51     ` Matthias Kaehlcke
2019-08-16 17:51       ` Matthias Kaehlcke
2019-08-16 19:47       ` Uwe Kleine-König
2019-08-16 19:47         ` Uwe Kleine-König
2019-08-16 19:47         ` Uwe Kleine-König
2019-08-16 21:10         ` Matthias Kaehlcke
2019-08-16 21:10           ` Matthias Kaehlcke
2019-08-19  5:46           ` Uwe Kleine-König
2019-08-19  5:46             ` Uwe Kleine-König
2019-08-19  5:46             ` Uwe Kleine-König
2019-08-19  9:50             ` Daniel Thompson
2019-08-19  9:50               ` Daniel Thompson
2019-08-19  9:50               ` Daniel Thompson
2019-08-19 10:21               ` Uwe Kleine-König
2019-08-19 10:21                 ` Uwe Kleine-König
2019-08-19 10:21                 ` Uwe Kleine-König
2019-08-19 11:16                 ` Daniel Thompson
2019-08-19 11:16                   ` Daniel Thompson
2019-08-19 12:29                   ` Uwe Kleine-König
2019-08-19 12:29                     ` Uwe Kleine-König
2019-08-20 14:49               ` Daniel Vetter
2019-08-20 14:49                 ` Daniel Vetter
2019-08-20 14:49                 ` Daniel Vetter
2019-08-21 14:16                 ` Daniel Thompson
2019-08-21 14:16                   ` Daniel Thompson
2019-08-21 14:16                   ` Daniel Thompson
2019-09-02  9:41   ` Lee Jones
2019-09-02  9:41     ` Lee Jones
2019-07-09 19:00 ` [PATCH v3 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves Matthias Kaehlcke
2019-07-09 19:00   ` Matthias Kaehlcke
2019-09-02  9:41   ` Lee Jones
2019-09-02  9:41     ` Lee Jones
2019-07-09 19:00 ` [PATCH v3 4/4] backlight: pwm_bl: Set scale type for brightness curves specified in the DT Matthias Kaehlcke
2019-07-09 19:00   ` Matthias Kaehlcke
2019-09-02  9:42   ` Lee Jones
2019-09-02  9:42     ` Lee Jones
2019-07-22 23:59 ` [PATCH v3 0/4] backlight: Expose brightness curve type through sysfs Matthias Kaehlcke
2019-07-22 23:59   ` Matthias Kaehlcke
2019-07-25 11:15   ` Lee Jones
2019-07-25 11:15     ` Lee Jones
2019-07-25 17:17     ` Matthias Kaehlcke
2019-07-25 17:17       ` Matthias Kaehlcke
2019-07-25 17:17       ` Matthias Kaehlcke
2019-08-05 10:37       ` Lee Jones
2019-08-05 10:37         ` Lee Jones

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