On Wed, Sep 06, 2023 at 03:48:35PM +0300, Dmitry Baryshkov wrote: > On Wed, 6 Sept 2023 at 15:44, Heikki Krogerus > <heikki.krogerus@xxxxxxxxxxxxxxx> wrote: > > > > On Tue, Sep 05, 2023 at 01:56:59PM +0300, Dmitry Baryshkov wrote: > > > Hi Heikki, > > > > > > On Tue, 5 Sept 2023 at 11:50, Heikki Krogerus > > > <heikki.krogerus@xxxxxxxxxxxxxxx> wrote: > > > > > > > > Hi Dmitry, > > > > > > > > On Mon, Sep 04, 2023 at 12:41:39AM +0300, Dmitry Baryshkov wrote: > > > > > The kdev->fwnode pointer is never set in drm_sysfs_connector_add(), so > > > > > dev_fwnode() checks never succeed, making the respective commit NOP. > > > > > > > > That's not true. The dev->fwnode is assigned when the device is > > > > created on ACPI platforms automatically. If the drm_connector fwnode > > > > member is assigned before the device is registered, then that fwnode > > > > is assigned also to the device - see drm_connector_acpi_find_companion(). > > > > > > > > But please note that even if drm_connector does not have anything in > > > > its fwnode member, the device may still be assigned fwnode, just based > > > > on some other logic (maybe in drivers/acpi/acpi_video.c?). > > > > > > > > > And if drm_sysfs_connector_add() is modified to set kdev->fwnode, it > > > > > breaks drivers already using components (as it was pointed at [1]), > > > > > resulting in a deadlock. Lockdep trace is provided below. > > > > > > > > > > Granted these two issues, it seems impractical to fix this commit in any > > > > > sane way. Revert it instead. > > > > > > > > I think there is already user space stuff that relies on these links, > > > > so I'm not sure you can just remove them like that. If the component > > > > framework is not the correct tool here, then I think you need to > > > > suggest some other way of creating them. > > > > > > The issue (that was pointed out during review) is that having a > > > component code in the framework code can lead to lockups. With the > > > patch #2 in place (which is the only logical way to set kdev->fwnode > > > for non-ACPI systems) probing of drivers which use components and set > > > drm_connector::fwnode breaks immediately. > > > > > > Can we move the component part to the respective drivers? With the > > > patch 2 in place, connector->fwnode will be copied to the created > > > kdev's fwnode pointer. > > > > > > Another option might be to make this drm_sysfs component registration optional. > > > > You don't need to use the component framework at all if there is > > a better way of determining the connection between the DP and its > > Type-C connector (I'm assuming that that's what this series is about). > > You just need the symlinks, not the component. > > The problem is that right now this component registration has become > mandatory. And if I set the kdev->fwnode manually (like in the patch > 2), the kernel hangs inside the component code. > That's why I proposed to move the components to the place where they > are really necessary, e.g. i915 and amd drivers. So why can't we replace the component with the method you are proposing in this series of finding out the Type-C port also with i915, AMD, or whatever driver and platform (that's the only thing that component is used for)? Determining the connection between a DP and its Type-C connector is starting to get really important, so ideally we have a common solution for that. thanks, -- heikki
