From: Matthias Kaehlcke <mka@chromium.org>
To: Brian Norris <briannorris@google.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>,
Pavel Machek <pavel@ucw.cz>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
Doug Anderson <dianders@google.com>,
Rob Herring <robh+dt@kernel.org>,
Jingoo Han <jingoohan1@gmail.com>,
Richard Purdie <rpurdie@rpsys.net>,
Jacek Anaszewski <jacek.anaszewski@gmail.com>,
Guenter Roeck <groeck@google.com>,
Lee Jones <lee.jones@linaro.org>,
Alexandru Stan <amstan@google.com>,
linux-leds@vger.kernel.org,
devicetree <devicetree@vger.kernel.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
kernel@collabora.com
Subject: Re: [PATCH v3 3/4] backlight: pwm_bl: compute brightness of LED linearly to human eye.
Date: Tue, 11 Jun 2019 15:30:19 -0700 [thread overview]
Message-ID: <20190611223019.GH137143@google.com> (raw)
In-Reply-To: <CA+ASDXOq7KQ+f4KMh0gaC9hvXaxBDdsbiJxiTbeOJ9ZVaeNJag@mail.gmail.com>
On Tue, Jun 11, 2019 at 09:55:30AM -0700, Brian Norris wrote:
> On Tue, Jun 11, 2019 at 3:49 AM Daniel Thompson
> <daniel.thompson@linaro.org> wrote:
> > This is a long standing flaw in the backlight interfaces. AFAIK generic
> > userspaces end up with a (flawed) heuristic.
>
> Bingo! Would be nice if we could start to fix this long-standing flaw.
Agreed!
How could a fix look like, a sysfs attribute? Would a boolean value
like 'logarithmic_scale' or 'linear_scale' be enough or could more
granularity be needed?
The new attribute could be optional (it only exists if explicitly
specified by the driver) or be set to a default based on a heuristic
if not specified and be 'fixed' on a case by case basis. The latter
might violate "don't break userspace" though, so I'm not sure it's a
good idea.
next prev parent reply other threads:[~2019-06-11 22:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 11:30 [PATCH v3 0/4] backlight: pwm_bl: support linear interpolation and brightness to human eye Enric Balletbo i Serra
2018-02-08 11:30 ` [PATCH v3 1/4] backlight: pwm_bl: linear interpolation between brightness-levels Enric Balletbo i Serra
2018-04-06 15:46 ` Daniel Thompson
2018-02-08 11:30 ` [PATCH v3 2/4] dt-bindings: pwm-backlight: add a num-interpolation-steps property Enric Balletbo i Serra
2018-02-18 22:49 ` Rob Herring
2018-02-08 11:30 ` [PATCH v3 3/4] backlight: pwm_bl: compute brightness of LED linearly to human eye Enric Balletbo i Serra
2018-04-06 15:51 ` Daniel Thompson
2019-06-07 22:19 ` Matthias Kaehlcke
2019-06-08 21:02 ` Pavel Machek
2019-06-10 10:00 ` Enric Balletbo i Serra
2019-06-10 20:39 ` Matthias Kaehlcke
2019-06-10 21:02 ` Enric Balletbo i Serra
2019-06-10 21:54 ` Matthias Kaehlcke
2019-06-10 20:52 ` Matthias Kaehlcke
2019-06-11 10:49 ` Daniel Thompson
2019-06-11 16:55 ` Brian Norris
2019-06-11 22:30 ` Matthias Kaehlcke [this message]
2019-06-12 9:54 ` Pavel Machek
2019-06-12 11:03 ` Daniel Thompson
2019-06-12 19:26 ` Matthias Kaehlcke
2019-06-12 19:47 ` Daniel Thompson
2019-06-12 21:59 ` Matthias Kaehlcke
2019-06-17 13:01 ` Pavel Machek
2019-06-17 20:03 ` Matthias Kaehlcke
[not found] ` <20180208113032.27810-1-enric.balletbo-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
2018-02-08 11:30 ` [PATCH v3 4/4] dt-bindings: pwm-backlight: move brightness-levels to optional Enric Balletbo i Serra
2018-03-19 16:04 ` [PATCH v3 0/4] backlight: pwm_bl: support linear interpolation and brightness to human eye Enric Balletbo Serra
2018-03-20 11:22 ` Daniel Thompson
2018-03-20 12:13 ` Enric Balletbo Serra
2018-04-06 15:54 ` Daniel Thompson
2018-04-09 8:17 ` Lee Jones
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