Messages in this thread | | | Date | Thu, 05 Sep 2013 01:03:59 +0300 | From | Mikko Perttunen <> | Subject | Re: [PATCH v2 3/6] host1x: hdmi: Enable Vdd earlier for hotplug/DDC |
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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.
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