On Thu, Dec 13, 2012 at 10:58:55AM -0700, Stephen Warren wrote: > On 12/13/2012 01:57 AM, Thierry Reding wrote: > > On Thu, Dec 13, 2012 at 10:48:55AM +0200, Terje Bergström wrote: > >> On 12.12.2012 18:08, Thierry Reding wrote: > >>> I've briefly discussed this with Stephen on IRC because I > >>> thought I had remembered him objecting to the idea of adding a > >>> dummy device just for this purpose. It turns out, however, that > >>> what he didn't like was to add a dummy node to the DT just to > >>> make this happen, but he has no (strong) objections to a dummy > >>> platform device. > >>> > >>> While I'm not very happy about that solution, I've been going > >>> over it for a week now and haven't come up with any better > >>> alternative that doesn't have its own disadvantages. So perhaps > >>> we should go ahead and implement that. For the host1x driver > >>> this really just means creating a platform device and adding it > >>> to the system, with some of the fields tweaked to make things > >>> work. > >> > >> Even the virtual device is not too beautiful. The problem is that > >> the virtual device is not physical parent for DC, HDMI, etc, so > >> dev_get_drvdata(pdev->dev.parent) returns the data from host1x > >> device, not the virtual device. > >> > >> We'll post with something that goes around this, but it's not > >> going to be too pretty. Let's try to find the solution once we > >> get the code out. > > > > After some more discussion with Stephen on IRC we came to the > > conclusion that the easiest might be to have tegra-drm call into > > host1x with something like: > > > > void host1x_set_drm_device(struct host1x *host1x, struct device > > *dev); > > If host1x is registering the dummy device that causes tegradrm to be > instantiated, then presumably there's no need for the API above, since > host1x will already have the struct device * for tegradrm, since it > created it? Right, that won't be necessary of course. As long as the driver-private data of the device stays NULL until tegra-drm is ready (has finished probing) just getting the struct device from the clients and looking at that should be enough. Thierry
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