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@xxxxxxxxxxxxxxx >> 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. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
