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HDMI sinks are permitted to de-assert and re-assert the HPD signal to indicate that their EDID has been updated, which may not involve a change of video information. An example of where such a situation can arise is when an AV receiver is connected between the source and the display device. Events which can cause the HPD to be deasserted include: * turning on or switching to standby the AV receiver. * turning on or switching to standby the display device. Each of these can change the entire EDID data, or just a part of the EDID data - it's up to the connected HDMI sink to do what they desire here. For example - with the AV receiver and display device both in standby, a source connected to the AV receiver may provide its own EDID to the source. - turning on the display device causes the display device's EDID to be made available in an unmodified form to the source. - subsequently turning on the AV receiver then provides a modified version of the display device's EDID. Moreover, HPD doesn't tell us whether something is actually listening on the HDMI TDMS signals. The phy gives us a set of RXSENSE indications which tell us whether there is a sink connected to the TMDS signals. Currently, we use the HPD signal to enable or disable the HDMI block, which is questionable when HPD is used in this manner. Using the RXSENSE would be more appropriate, but there is some bad behaviour which needs to be coped with. The iMX6 implementation lets the TMDS signals float when the phy is "powered down", which cause spurious interrupts. Rather than just using RXSENSE, use RXSENSE and HPD becoming both active to signal the presence of a device, but loss of RXSENSE to indicate that the device has been unplugged. The side effect of this change is that a sink deasserting the HPD signal to cause a re-read of the EDID data will not cause the bridge to immediately disable the video signal. Tested-by: Philipp Zabel <p.zabel@pengutronix.de> Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> |
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| dw_hdmi.c | ||
| dw_hdmi.h | ||
| Kconfig | ||
| Makefile | ||
| nxp-ptn3460.c | ||
| parade-ps8622.c | ||