From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH v2 3/6] host1x: hdmi: Enable Vdd earlier for hotplug/DDC Date: Wed, 04 Sep 2013 16:24:26 -0600 Message-ID: <5227B31A.3070404@wwwdotorg.org> References: <1377704922-2824-1-git-send-email-mperttunen@nvidia.com> <1377704922-2824-4-git-send-email-mperttunen@nvidia.com> <52277F90.40109@wwwdotorg.org> <5227AE4F.8050603@kapsi.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5227AE4F.8050603-/1wQRMveznE@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mikko Perttunen Cc: Mikko Perttunen , thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, tbergstrom-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 09/04/2013 04:03 PM, Mikko Perttunen wrote: > 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-u79uwXL29TY76Z2rM5mHXA@public.gmane.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. Ah OK, then this code change makes sense. It'd be useful to put what you just wrote into the binding doc. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756460Ab3IDWYc (ORCPT ); Wed, 4 Sep 2013 18:24:32 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:38519 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753309Ab3IDWYa (ORCPT ); Wed, 4 Sep 2013 18:24:30 -0400 Message-ID: <5227B31A.3070404@wwwdotorg.org> Date: Wed, 04 Sep 2013 16:24:26 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Mikko Perttunen 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> <5227AE4F.8050603@kapsi.fi> In-Reply-To: <5227AE4F.8050603@kapsi.fi> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/04/2013 04:03 PM, Mikko Perttunen wrote: > 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. Ah OK, then this code change makes sense. It'd be useful to put what you just wrote into the binding doc.