From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp.nokia.com ([147.243.1.48]:60496 "EHLO mgw-sa02.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755212Ab1DFJ0K (ORCPT ); Wed, 6 Apr 2011 05:26:10 -0400 Message-ID: <4D9C31A4.3050705@maxwell.research.nokia.com> Date: Wed, 06 Apr 2011 12:25:56 +0300 From: Sakari Ailus MIME-Version: 1.0 To: Nayden Kanchev CC: "linux-media@vger.kernel.org" , Guennadi Liakhovetski , Laurent Pinchart , Hans Verkuil , Cohen David Abraham , Kim HeungJun Subject: Re: [RFC v2] V4L2 API for flash devices References: <4D9C2000.9090500@maxwell.research.nokia.com> <4D9C2670.2000603@mm-sol.com> In-Reply-To: <4D9C2670.2000603@mm-sol.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-ID: Sender: Nayden Kanchev wrote: > Hi Sakari, > > Thanks for the update. I have just one comment about strobe types. Hi Nayden, Thanks for the comments! > > > > On 04/06/2011 11:10 AM, Sakari Ailus wrote: >> - Added an open question on a new control: >> V4L2_CID_FLASH_EXTERNAL_STROBE_WHENCE. >> >> >> > >> 2. External strobe edge / level >> ------------------------------- >> >> No use is seen currently for this, but it may well appear, and the >> hardware supports this. Level based trigger should be used since it is >> more precise. >> >> V4L2_CID_FLASH_EXTERNAL_STROBE_WHENCE >> >> Whether the flash controller considers external strobe as edge, when the >> only limit of the strobe is the timeout on flash controller, or level, >> when the flash strobe will last as long as the strobe signal, or as long >> until the timeout expires. >> >> enum v4l2_flash_external_strobe_whence { >> V4L2_CID_FLASH_EXTERNAL_STROBE_LEVEL, >> V4L2_CID_FLASH_EXTERNAL_STROBE_EDGE, >> }; Removed "CID_": enum v4l2_flash_external_strobe_whence { V4L2_FLASH_EXTERNAL_STROBE_LEVEL, V4L2_FLASH_EXTERNAL_STROBE_EDGE, }; I guess this should be an rw menu control for LED flash? > > I agree that control over the strobe usage (level/edge) is required. > Although we have some bad experience will lack of detailed information > how exactly the flash chip will use those signals. > > For example with AS3645A flash driver strobing by edge produced really > strange flash output - light intensity was changing during the process > and flash was stopped before the HW timeout. > > On the other hand strobing by level didn't cause problems. > > So even if HW supports some functionally we should prevent such > malfunctioning by adding some restrictions in the board code also. I agree. The control should be probably exposed to tell which kind of functionality does the flash chip provide, even if the menu has just one option in it. > I would also rename xxx_STROBE_WHENCE to xxx_STROBE_TYPE but it is just > a suggestion :) Sounds good to me. V4L2_CID_FLASH_STROBE_MODE should be renamed to V4L2_CID_FLASH_STROBE_WHENCE. That proper use of whence IMO. :-) Regards, -- Sakari Ailus sakari.ailus@maxwell.research.nokia.com