Messages in this thread | | | Date | Wed, 20 Jul 2022 14:12:21 +0100 | From | Sudeep Holla <> | Subject | Re: [PATCH v5] amba: Remove deferred device addition |
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On Tue, Jul 19, 2022 at 11:20:10AM -0700, Saravana Kannan wrote: > The uevents generated for an amba device need PID and CID information > that's available only when the amba device is powered on, clocked and > out of reset. So, if those resources aren't available, the information > can't be read to generate the uevents. To workaround this requirement, > if the resources weren't available, the device addition was deferred and > retried periodically. > > However, this deferred addition retry isn't based on resources becoming > available. Instead, it's retried every 5 seconds and causes arbitrary > probe delays for amba devices and their consumers. > > Also, maintaining a separate deferred-probe like mechanism is > maintenance headache. > > With this commit, instead of deferring the device addition, we simply > defer the generation of uevents for the device and probing of the device > (because drivers needs PID and CID to match) until the PID and CID > information can be read. This allows us to delete all the amba specific > deferring code and also avoid the arbitrary probing delays. > > Cc: Rob Herring <robh@kernel.org> > Cc: Ulf Hansson <ulf.hansson@linaro.org> > Cc: Saravana Kannan <saravanak@google.com> > Cc: Linus Walleij <linus.walleij@linaro.org> > Cc: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
on Juno with linux-next(which had the reported issue [1]) + this patch(which fixes the issue)
-- Regards, Sudeep
[1] https://lore.kernel.org/all/20220701150848.75eeprptmb5beip7@bogus/
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