From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761456Ab3IDWEN (ORCPT ); Wed, 4 Sep 2013 18:04:13 -0400 Received: from mail.kapsi.fi ([217.30.184.167]:42221 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757147Ab3IDWEL (ORCPT ); Wed, 4 Sep 2013 18:04:11 -0400 Message-ID: <5227AE4F.8050603@kapsi.fi> Date: Thu, 05 Sep 2013 01:03:59 +0300 From: Mikko Perttunen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130806 Thunderbird/17.0.8 MIME-Version: 1.0 To: Stephen Warren CC: Mikko Perttunen , thierry.reding@gmail.com, tbergstrom@nvidia.com, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/6] host1x: hdmi: Enable Vdd earlier for hotplug/DDC References: <1377704922-2824-1-git-send-email-mperttunen@nvidia.com> <1377704922-2824-4-git-send-email-mperttunen@nvidia.com> <52277F90.40109@wwwdotorg.org> In-Reply-To: <52277F90.40109@wwwdotorg.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 82.130.34.11 X-SA-Exim-Mail-From: mikko.perttunen@kapsi.fi X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/04/2013 09:44 PM, Stephen Warren wrote: > On 08/28/2013 09:48 AM, Mikko Perttunen wrote: >> The Vdd regulator used to be enabled only at tegra_output_hdmi_enable, >> which is called after a sink is detected. However, the HDMI hotplug pin >> works by returning the voltage supplied by the Vdd pin, so this meant >> that the hotplug pin was never asserted and the sink was not detected >> unless the Vdd regulator was set to be always on. >> >> This patch moves the enable to the tegra_hdmi_drm_init function to make >> sure the regulator will get enabled. > > The DT binding document isn't very clear on this topic (and should be > fixed): What is this regulator intended to control? If this regulator > solely controls the supply to the hotplug detection circuit, this change > makes sense. If the regulator mainly supplies something else (e.g. part > of the HDMI core on the Tegra chip), then perhaps this change isn't > correct. The correct approach might be to introduce another (optional) > regulator specifically for the hotplug circuit. Presumably both DT > properties vdd-supply and hotplug-supply could point at the same > regulator if that's the way the HW was wired up. > -- > To unsubscribe from this list: send the line "unsubscribe linux-tegra" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > AFAICT, it controls the Vdd pin on the HDMI port, so it just affects the hotplug pin and the DDC I2C bus power.