On Thu, Mar 13, 2025 at 12:56:56PM +0100, Luca Ceresoli wrote: > Hello Maxime, > > On Fri, 7 Feb 2025 12:47:51 +0100 > Maxime Ripard <mripard@xxxxxxxxxx> wrote: > > On Thu, Feb 06, 2025 at 07:14:29PM +0100, Luca Ceresoli wrote: > > > DRM bridges are currently considered as a fixed element of a DRM card, and > > > thus their lifetime is assumed to extend for as long as the card > > > exists. New use cases, such as hot-pluggable hardware with video bridges, > > > require DRM bridges to be added and removed to a DRM card without tearing > > > the card down. This is possible for connectors already (used by DP MST), so > > > add this possibility to DRM bridges as well. > > > > > > Implementation is based on drm_connector_init() as far as it makes sense, > > > and differs when it doesn't. A difference is that bridges are not exposed > > > to userspace, hence struct drm_bridge does not embed a struct > > > drm_mode_object which would provide the refcount. Instead we add to struct > > > drm_bridge a refcount field (we don't need other struct drm_mode_object > > > fields here) and instead of using the drm_mode_object_*() functions we > > > reimplement from those functions the few lines that drm_bridge needs for > > > refcounting. > > > > > > Also add a new devm_drm_bridge_alloc() macro to allocate a new refcounted > > > bridge. > > > > > > Signed-off-by: Luca Ceresoli <luca.ceresoli@xxxxxxxxxxx> > > > > So, a couple of general comments: > > > > - I've said it a couple of times already, but I really think you're > > making it harder than necessary for you here. This (and only this!) > > should be the very first series you should be pushing. The rest can > > only ever work if that work goes through, and it's already hard enough > > as it is. So, split that patch into a series of its own, get that > > merged, and then we will be able to deal with panels conversion and > > whatever. That's even more true with panels since there's ongoing work > > that will make it easier for you too. So the best thing here is > > probably to wait. > > > > - This patch really needs to be split into several patches, something > > along the lines of: > > > > + Creating devm_drm_bridge_alloc() > > + Adding refcounting > > + Taking the references in all the needed places > > + Converting a bunch of drivers > > After reading Anusha's "[PATCH RFC 0/2] drm/panel: Refcounted panel > allocation" [0] I think I need a clarification about the 4 steps you had > outlined in the above quoted text. Are you suggesting those are four > _series_, and you'd want to see a series only creating > devm_drm_bridge_alloc() as a first step, similarly to Anusha's work? > > That was not my understanding so far, and so I've been working on a > series containing all 4 items, and it's growing very long due to item 3 > needing to touch many dozen drivers which need to put a bridge (many > are identical oneliner patches though). I believe I've clarified it already in Anusha's series, but I think a reasonable series for *early* work would be the bullet points 1, 2, a bit of 3 and a bit of 4. Once the API is agreed upon, 1, 2 and 4 should be in the same series. As you've pointed out, item 3 can be large, so I don't really mind either way. Maxime
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