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>, Matthias Kaehlcke <mka@chromium.org> Subject: [PATCH 0/4] backlight: Expose brightness curve type through sysfs Date: Thu, 13 Jun 2019 12:43:22 -0700 [thread overview] Message-ID: <20190613194326.180889-1-mka@chromium.org> (raw) 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 is currently opaque to userspace, so userspace often relies on 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 a new sysfs attribute. Matthias Kaehlcke (4): MAINTAINERS: Add entry for stable backlight sysfs ABI documentation backlight: Expose brightness curve type through sysfs backlight: pwm_bl: Set scale type for CIE 1931 curves backlight: pwm_bl: Set scale type for brightness curves specified in the DT .../ABI/testing/sysfs-class-backlight | 32 +++++++++++++++++++ MAINTAINERS | 2 ++ drivers/video/backlight/backlight.c | 22 +++++++++++++ drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++- include/linux/backlight.h | 10 ++++++ 5 files changed, 95 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight -- 2.22.0.rc2.383.gf4fbbf30c2-goog
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>, Matthias Kaehlcke <mka@chromium.org> Subject: [PATCH 0/4] backlight: Expose brightness curve type through sysfs Date: Thu, 13 Jun 2019 19:43:22 +0000 [thread overview] Message-ID: <20190613194326.180889-1-mka@chromium.org> (raw) 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 is currently opaque to userspace, so userspace often relies on 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 a new sysfs attribute. Matthias Kaehlcke (4): MAINTAINERS: Add entry for stable backlight sysfs ABI documentation backlight: Expose brightness curve type through sysfs backlight: pwm_bl: Set scale type for CIE 1931 curves backlight: pwm_bl: Set scale type for brightness curves specified in the DT .../ABI/testing/sysfs-class-backlight | 32 +++++++++++++++++++ MAINTAINERS | 2 ++ drivers/video/backlight/backlight.c | 22 +++++++++++++ drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++- include/linux/backlight.h | 10 ++++++ 5 files changed, 95 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight -- 2.22.0.rc2.383.gf4fbbf30c2-goog
next reply other threads:[~2019-06-13 19:43 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-13 19:43 Matthias Kaehlcke [this message] 2019-06-13 19:43 ` [PATCH 0/4] backlight: Expose brightness curve type through sysfs Matthias Kaehlcke 2019-06-13 19:43 ` [PATCH 1/4] MAINTAINERS: Add entry for stable backlight sysfs ABI documentation Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-19 11:05 ` Daniel Thompson 2019-06-19 11:05 ` Daniel Thompson 2019-06-19 11:05 ` Daniel Thompson 2019-06-13 19:43 ` [PATCH 2/4] backlight: Expose brightness curve type through sysfs Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-13 21:56 ` Matthias Kaehlcke 2019-06-13 21:56 ` Matthias Kaehlcke 2019-06-13 19:43 ` [PATCH 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-19 9:17 ` Enric Balletbo i Serra 2019-06-19 9:17 ` Enric Balletbo i Serra 2019-06-21 12:55 ` Daniel Thompson 2019-06-21 12:55 ` Daniel Thompson 2019-06-27 9:24 ` Lee Jones 2019-06-27 9:24 ` Lee Jones 2019-06-27 9:24 ` Lee Jones 2019-06-27 15:49 ` Daniel Thompson 2019-06-27 15:49 ` Daniel Thompson 2019-06-27 15:49 ` Daniel Thompson 2019-06-13 19:43 ` [PATCH 4/4] backlight: pwm_bl: Set scale type for brightness curves specified in the DT Matthias Kaehlcke 2019-06-13 19:43 ` Matthias Kaehlcke 2019-06-21 13:10 ` Daniel Thompson 2019-06-21 13:10 ` Daniel Thompson 2019-06-24 18:54 ` Matthias Kaehlcke 2019-06-24 18:54 ` Matthias Kaehlcke
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