From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout1.w1.samsung.com ([210.118.77.11]:22328 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbaLDJm7 (ORCPT ); Thu, 4 Dec 2014 04:42:59 -0500 Message-id: <54802C9F.8030101@samsung.com> Date: Thu, 04 Dec 2014 10:42:55 +0100 From: Jacek Anaszewski MIME-version: 1.0 To: Sakari Ailus Cc: linux-leds@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, kyungmin.park@samsung.com, b.zolnierkie@samsung.com, pavel@ucw.cz, cooloney@gmail.com, rpurdie@rpsys.net, s.nawrocki@samsung.com, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org Subject: Re: [PATCH/RFC v9 02/19] Documentation: leds: Add description of LED Flash class extension References: <1417622814-10845-1-git-send-email-j.anaszewski@samsung.com> <1417622814-10845-3-git-send-email-j.anaszewski@samsung.com> <20141203170818.GN14746@valkosipuli.retiisi.org.uk> In-reply-to: <20141203170818.GN14746@valkosipuli.retiisi.org.uk> Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, Thanks for the review. On 12/03/2014 06:08 PM, Sakari Ailus wrote: > Hi Jacek, > > On Wed, Dec 03, 2014 at 05:06:37PM +0100, Jacek Anaszewski wrote: >> The documentation being added contains overall description of the >> LED Flash Class and the related sysfs attributes. >> >> Signed-off-by: Jacek Anaszewski >> Acked-by: Kyungmin Park >> Cc: Bryan Wu >> Cc: Richard Purdie >> --- >> Documentation/leds/leds-class-flash.txt | 50 +++++++++++++++++++++++++++++++ >> 1 file changed, 50 insertions(+) >> create mode 100644 Documentation/leds/leds-class-flash.txt >> >> diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt >> new file mode 100644 >> index 0000000..82e58b1 >> --- /dev/null >> +++ b/Documentation/leds/leds-class-flash.txt >> @@ -0,0 +1,50 @@ >> + >> +Flash LED handling under Linux >> +============================== >> + >> +Some LED devices support two modes - torch and flash. The modes are >> +supported by the LED class (see Documentation/leds/leds-class.txt) >> +and LED Flash class respectively. >> + >> +In order to enable support for flash LEDs CONFIG_LEDS_CLASS_FLASH symbol >> +must be defined in the kernel config. A flash LED driver must register >> +in the LED subsystem with led_classdev_flash_register to gain flash >> +capabilities. >> + >> +Following sysfs attributes are exposed for controlling flash led devices: >> + >> + - flash_brightness - flash LED brightness in microamperes (RW) >> + - max_flash_brightness - maximum available flash LED brightness (RO) >> + - flash_timeout - flash strobe duration in microseconds (RW) >> + - max_flash_timeout - maximum available flash strobe duration (RO) >> + - flash_strobe - flash strobe state (RW) >> + - flash_sync_strobe - one flash device can control more than one >> + sub-led; when this atrribute is set to 1 > > s/atrribute/attribute/ > >> + the flash led will be strobed synchronously >> + with the other one controlled by the same >> + device; flash timeout setting is inherited >> + from the led being strobed explicitly and >> + flash brightness setting of a sub-led's >> + being synchronized is used (RW) > > The flash brightness shouldn't be determined by the strobed LED. If this is > a property of the hardware, then be it, but in general no, it it shouldn't > be an interface requirement. I think this should just say that the strobe is > synchronised. I intended this to sound exactly as you laid it out above, but maybe it is obscure English. "and flash brightness setting of a sub-led >>>being synchronized<<< is used" - from my point of view the led being synchronized is the one that isn't strobed explicitly. But I'm ok with confining ourselves only to saying that strobe is synchronized. > How does the user btw. figure out which flash LEDs may be strobed > synchronously using the LED flash interface? The flash_sync_strobe argument is absent if synchronized strobe is not available for a LED. The driver defines this by setting newly added LED_DEV_CAP_COMPOUND flag. Best Regards, Jacek Anaszewski