Hi Thierry, å¨ 09/03/2015 05:04 PM, Thierry Reding åé: > On Thu, Sep 03, 2015 at 12:27:47PM +0800, Yakir Yang wrote: >> Hi Rob, >> >> å¨ 09/03/2015 04:17 AM, Rob Herring åé: >>> On Tue, Sep 1, 2015 at 1:14 AM, Yakir Yang <ykk at rock-chips.com> wrote: >>>> Some edp screen do not have hpd signal, so we can't just return >>>> failed when hpd plug in detect failed. >>> This is a property of the panel (or connector perhaps), so this >>> property should be located there. At least, it is a common issue and >>> not specific to this chip. We could have an HDMI connector and failed >>> to hook up HPD for example. A connector node is also where hpd-gpios >>> should be located instead (and are already defined by >>> ../bindings/video/hdmi-connector.txt). Perhaps we need a eDP connector >>> binding, too. >> Yep, I agree with your front point, it is a property of panel, not specific >> to eDP controller, so this code should handle in connector logic. > From your description it sounds more like this is in fact a property of > the panel. Or maybe I should say "quirk". If the panel doesn't generate > the HPD signal, then that should be a property of the panel, not the > connector. The eDP specification mandates that connectors have a HPD > signal, though it allows the "HPD conductor in the connector cable" to > be omitted if not used by the source. I'd consider the cable to belong > to the panel rather than the connector, so absence of HPD, either > because the cable doesn't have the conductor or because the panel does > not generate the signal, should be a quirk of the panel. > > That said you could have a panel that supports HPD connected via a cable > that doesn't transmit it, so this would be a per-board variant and hence > should be a device tree property rather than hard-coded in some panel > driver. > > Conversely, if the panel isn't capable of generating an HPD signal, then > I don't think it would be appropriate to make it a DT property. It would > be better to hard-code it in the driver, lest someone forget to set the > property in DT and get stuck with a device that isn't operational.
Oh, you're right, if it's a cable quirk, then DT property would be okay, if it is a problem of panel, then maybe hard-code in driver would be better. After look up for the document of panel "innolux,n116bge", I haven't see any description of hot plug signal, and even not found in PIN ASSIGNMENT. So I believe it's a panel problem, that's to say it should handle in panel driver. Hmm... But I don't know how to cover the whole hpd situation in panel detect, it looks complicate *_* And Russell have remind that DRM .force is another way to handle this one, but I haven't understand it very well. I see we need make connector->force = DRM_FORCE_ON, then we can enable eDP in connector->funcs->force(). But I don't how to handle connector->force automatically without DT property, could some guys help here :-D Thanks, - Yakir -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20150906/101724d1/attachment-0001.html>
