From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH] backlight: lcd: add driver for raster-type lcd's with gpio controlled panel reset Date: Wed, 11 Jan 2012 17:45:41 +0000 Message-ID: <20120111174540.GE24213@opensource.wolfsonmicro.com> References: <1325778146-27056-1-git-send-email-thomas.abraham@linaro.org> <4F05F509.6020405@metafoo.de> <20120106064929.GB3496@opensource.wolfsonmicro.com> <20120107172826.GA355@opensource.wolfsonmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from opensource.wolfsonmicro.com ([80.75.67.52]:53816 "EHLO opensource.wolfsonmicro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757900Ab2AKRpm (ORCPT ); Wed, 11 Jan 2012 12:45:42 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Thomas Abraham Cc: Lars-Peter Clausen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rpurdie@rpsys.net, linux-samsung-soc@vger.kernel.org, grant.likely@secretlab.ca, rob.herring@calxeda.com, kgene.kim@samsung.com, jg1.han@samsung.com, kyungmin.park@samsung.com, cbou@mail.ru, kwangwoo.lee@gmail.com, augulis.darius@gmail.com, ben-linux@fluff.org, patches@linaro.org On Wed, Jan 11, 2012 at 04:21:57PM +0530, Thomas Abraham wrote: > In the case of Exynos4 based Origen board, buck7 of max8997 supplies > power to the lcd panel. buck7 is capable of supplying power at > different voltage levels but for Origen board, it is required to > supply only 3.3V. The constraints for buck7 can specify 'apply_uV' and > this will ensure that buck7 is configured to supply 3.3V. > But 'apply_uV' seems to be not ideal for regulators that supply power > to lcd panels. It would be better to power lcd panels only when video > data has to be displayed. What makes you say this? Enabling and disabling a regulator are entirely orthogonal to setting the regulator voltage. From mboxrd@z Thu Jan 1 00:00:00 1970 From: broonie@opensource.wolfsonmicro.com (Mark Brown) Date: Wed, 11 Jan 2012 17:45:41 +0000 Subject: [PATCH] backlight: lcd: add driver for raster-type lcd's with gpio controlled panel reset In-Reply-To: References: <1325778146-27056-1-git-send-email-thomas.abraham@linaro.org> <4F05F509.6020405@metafoo.de> <20120106064929.GB3496@opensource.wolfsonmicro.com> <20120107172826.GA355@opensource.wolfsonmicro.com> Message-ID: <20120111174540.GE24213@opensource.wolfsonmicro.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jan 11, 2012 at 04:21:57PM +0530, Thomas Abraham wrote: > In the case of Exynos4 based Origen board, buck7 of max8997 supplies > power to the lcd panel. buck7 is capable of supplying power at > different voltage levels but for Origen board, it is required to > supply only 3.3V. The constraints for buck7 can specify 'apply_uV' and > this will ensure that buck7 is configured to supply 3.3V. > But 'apply_uV' seems to be not ideal for regulators that supply power > to lcd panels. It would be better to power lcd panels only when video > data has to be displayed. What makes you say this? Enabling and disabling a regulator are entirely orthogonal to setting the regulator voltage.