On Tue, Mar 07, 2023 at 11:09:01AM -0800, Saravana Kannan wrote:
> On Tue, Mar 7, 2023 at 11:02 AM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > From: Saravana Kannan <saravanak@xxxxxxxxxx>
> >
> > [ Upstream commit 67cad5c67019c38126b749621665b6723d3ae7e6 ]
> >
> > fw_devlink uses DL_FLAG_SYNC_STATE_ONLY device link flag for two
> > purposes:
> >
> > 1. To allow a parent device to proxy its child device's dependency on a
> > supplier so that the supplier doesn't get its sync_state() callback
> > before the child device/consumer can be added and probed. In this
> > usage scenario, we need to ignore cycles for ensure correctness of
> > sync_state() callbacks.
> >
> > 2. When there are dependency cycles in firmware, we don't know which of
> > those dependencies are valid. So, we have to ignore them all wrt
> > probe ordering while still making sure the sync_state() callbacks
> > come correctly.
> >
> > However, when detecting dependency cycles, there can be multiple
> > dependency cycles between two devices that we need to detect. For
> > example:
> >
> > A -> B -> A and A -> C -> B -> A.
> >
> > To detect multiple cycles correct, we need to be able to differentiate
> > DL_FLAG_SYNC_STATE_ONLY device links used for (1) vs (2) above.
> >
> > To allow this differentiation, add a DL_FLAG_CYCLE that can be use to
> > mark use case (2). We can then use the DL_FLAG_CYCLE to decide which
> > DL_FLAG_SYNC_STATE_ONLY device links to follow when looking for
> > dependency cycles.
> >
> > Fixes: 2de9d8e0d2fe ("driver core: fw_devlink: Improve handling of cyclic dependencies")
> > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> > Tested-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
> > Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> > Tested-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > Tested-by: Luca Weiss <luca.weiss@xxxxxxxxxxxxx> # qcom/sm7225-fairphone-fp4
> > Link: https://lore.kernel.org/r/20230207014207.1678715-6-saravanak@xxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
>
> These fw_devlink patches weren't tested with 5.15. It's also an
> extensive refactor. So I'm a little worried if it'll be finicky and
> break things in a kernel that's a year old.
>
> Unless someone specifically wants these patches in 5.15, I'd prefer we
> don't pick it up in 5.15.
Good point, I'll go drop this from the 5.15.y queue.
thanks,
greg k-h
