From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sourav Poddar Subject: Re: [PATCH] ARM: DTS: omap4-sdp: Add regulator for LCD backlight (pwm-backlight) Date: Thu, 28 Nov 2013 15:39:17 +0530 Message-ID: <5297164D.9060400@ti.com> References: <1385630924-16392-1-git-send-email-peter.ujfalusi@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from comal.ext.ti.com ([198.47.26.152]:40539 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750949Ab3K1KJp (ORCPT ); Thu, 28 Nov 2013 05:09:45 -0500 In-Reply-To: <1385630924-16392-1-git-send-email-peter.ujfalusi@ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Peter Ujfalusi , Benoit Cousson Cc: Tony Lindgren , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, tomi.valkeinen@ti.com On Thursday 28 November 2013 02:58 PM, Peter Ujfalusi wrote: > Since in DT booted kernel dummy regulators are no longer supported we need > to provide valid phandle for the regulator needed by the backlight. > On the board VBAT is used to power the LCD backlight(s). > > Signed-off-by: Peter Ujfalusi > --- > Hi, > > This patch is needed for 3.13 to get the LCD backlight to work again. Is this usage of power supply a mandatory requirement? There is a thread which discusses this issue[1]: http://www.spinics.net/lists/arm-kernel/msg288215.html According to the above, regulator framework have support in 3.13-rc1 to returns a dummy regulator if there is none specified in the dts data. Thierry told that there seems to be a bug in regulator in handling these case. Though, I also posted a patch on pwm a couple of days ago[2] [2]: https://patchwork.kernel.org/patch/3246711/ I posted it without "power-supply" by testing it with the solution proposed in [1]. If I dont use the solution[1], it fails for me also.