Hi Philipp,
On 01/07/2014 04:29 AM, Philipp Zabel wrote:
Am Montag, den 06.01.2014, 19:31 -0700 schrieb Eric Nelson:
Hi Russell,
On 01/06/2014 10:46 AM, Russell King - ARM Linux wrote:
On Mon, Jan 06, 2014 at 06:41:28PM +0100, Philipp Zabel wrote:
Hi Eric,
Am Freitag, den 03.01.2014, 12:14 -0700 schrieb Eric Nelson:
This is an issue we've seen before. The SABRE Lite board has
a voltage divider on the HPD pins and some monitors (esp. DVI
monitors) either don't drive things high enough to assert HPD or
bounce with connect/disconnect.
Yes, I used a DVI monitor.
We've instrumented our 3.0.35 kernels to use the RX_SENSE bits
instead.
Reacting to RX_SENSE0 instead of HPD seems to work.
However, it's non-compliant, because HPD can be lowered and raised by
the sink when it changes its EDID data (eg, because you're connected
through a switch and the routing has been changed.)
So, reacting to RX_SENSE0 instead of HPD has to be a work-around enabled
only for those boards which are broken in this regard.
I understand. We'll need to carry some patches for a while though,
since there are lots of these boards in the wild.
Could you point me to your changes? Maybe this could be added to
mainline as a quirk enabled by a device tree property on sabrelite only.
We only have them for 3.0.35 at the moment.
Here's the patch to use RXSENSE instead of HPD
https://github.com/boundarydevices/linux-imx6/commit/c0439e262bb6c23887d96466b2ab7916aa0488d9
A follow-up patch disables the disconnect detection entirely
unless requested:
https://github.com/boundarydevices/linux-imx6/commit/d9cd79d11ff9f7a7f89cbc94b68757b67cdfe5fc
Regards,
Eric
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