On Mon, Feb 10, 2025 at 06:12:03PM +0100, Luca Ceresoli wrote: > Hello Maxime, Dmitry, > > On Mon, 10 Feb 2025 16:23:44 +0200 > Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > On Mon, 10 Feb 2025 at 14:31, Maxime Ripard <mripard@xxxxxxxxxx> > > wrote: > > > > > > On Fri, Feb 07, 2025 at 09:54:06PM +0200, Dmitry Baryshkov wrote: > > > > On Fri, Feb 07, 2025 at 12:47:51PM +0100, Maxime Ripard wrote: > > > > > Hi, > > > > > > > > > > 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. > > The idea you proposed was to handle the issues current panel bridge > code adds to the hotplug work by adding a .destroy callback and some > more devm magic. I explored the idea but even after some clarifications > from you it still didn't appear clearly doable and correct to me. And > even in the case it were perfectly correct and doable, it is based on > adding more complexity and "magic" on top of a topic that is already > hard to understand: panel_bridge lifetime. Not really, no. I told you several time that you shouldn't deal with panels yet. > So I opted for the other way: rework panel_bridge code so its lifetime > is clear and as one would expect (panel_bridge lifetime == panel > lifetime). > > Possibly more work for me, but now it's done and it's in these patches > so why waiting? No, it's not done. You have the same issue with panels than you are trying to fix with bridges: it's allocated through devm so they'll get destroyed too soon. The panel_bridge might work fine now, but the panel won't. So it's more work, more scope-creep, and more discussions. For example, I'm really not convinced on moving the drm_panel code under bridge. Splitting it up will allow you to at least merge the parts that are somewhat agreed upon. But do however you want :) Maxime
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