From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.nelson@boundarydevices.com (Eric Nelson) Date: Mon, 06 Jan 2014 19:31:53 -0700 Subject: [PATCH RFC 27/46] imx-drm: convert to componentised device support In-Reply-To: <20140106174606.GG27432@n2100.arm.linux.org.uk> References: <20140102212528.GD7383@n2100.arm.linux.org.uk> <1388767737.19394.32.camel@pizza.hi.pengutronix.de> <20140103170724.GT7383@n2100.arm.linux.org.uk> <1388770004.19394.42.camel@pizza.hi.pengutronix.de> <52C70C1A.3090108@boundarydevices.com> <1389030088.5590.30.camel@pizza.hi.pengutronix.de> <20140106174606.GG27432@n2100.arm.linux.org.uk> Message-ID: <52CB6719.6040604@boundarydevices.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. Regards, Eric