From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.nelson@boundarydevices.com (Eric Nelson) Date: Tue, 07 Jan 2014 08:30:41 -0700 Subject: [PATCH RFC 27/46] imx-drm: convert to componentised device support In-Reply-To: <1389094187.4815.24.camel@pizza.hi.pengutronix.de> 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> <52CB6719.6040604@boundarydevices.com> <1389094187.4815.24.camel@pizza.hi.pengutronix.de> Message-ID: <52CC1DA1.8030803@boundarydevices.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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