On Wed, May 09, 2018 at 03:00:38PM +0200, Boris Brezillon wrote: > Hello, > > This is a new attempt at fixing the "panel is missing" issue (described > in this thread [1]). I lost track of Eric's proposal, but I recently > proposed to address this problem through a new ->detect() hook in the > panel_funcs interface [2], which was rejected. > > So here is a new version based on the feedback I had from Daniel, > Thierry and Rob. > > The idea is to allow of_drm_find_panel() to return -ENODEV and let the > DRM driver decide what to do with that (silently ignore the missing > component and register the DRM device, or fail to register the DRM > device). > > Patch 1 changes the semantic of of_drm_find_panel() so that it returns > an ERR_PTR() instead of NULL when the panel is not found. This way > we'll be able to differentiate the "panel is missing" from "panel has > not been probed yet" errors. > > Patch 2 and 3 are adding new tests in of_drm_find_panel() and > drm_of_find_panel_or_bridge() to return -ENODEV when the status > property of the DT node is not set to "okay". > > Patch 4 is patching the VC4 DSI encoder driver to gracefully handle the > -ENODEV case and allow the registration of the DRM device when the DSI > device is disabled. > > Note that patch 6 which was modifying the panel status prop from the > I2C driver has been dropped because I'm not sure yet how to solve the > "force probe of deferred-probe devices even if no new devices have been > bound to drivers" problem. Anyway, even without this patch, the series > still makes sense to handle the case where devices are described in the > DT but marked "disabled" (either at compilation time or tweaked by the > bootloader). > > Regards, > > Boris > > Changes in v3: > - Dropped patch 1 since it's been acked by Thierry and should be > applied soon (either through the drm-tegra or drm-misc tree) > - Dropped patch 6 because we are still discussing who should mark > the device "disabled" or "fail" and how we should trigger the > re-probe of deferred-probe devices in this case > > Changes in v2: > - Everything :-) > > [1]https://lists.freedesktop.org/archives/dri-devel/2017-November/157688.html > [2]https://www.spinics.net/lists/dri-devel/msg174808.html I don't exactly remember what we decided should be the merge path for this, but I suspect someone else was supposed to pick it up because I ended up acking these patches. However, since this hasn't been applied yet, I decided to go ahead and apply this to drm-misc-next. Thierry
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