On Tue, Jun 18, 2019 at 12:53 PM Chen-Yu Tsai [off-list ref] wrote:

On Tue, Jun 18, 2019 at 3:12 PM Jagan Teki [off-list ref] wrote:

quoted

On Mon, Jun 17, 2019 at 6:31 PM Chen-Yu Tsai [off-list ref] wrote:

quoted

On Mon, Jun 17, 2019 at 7:45 PM Maxime Ripard [off-list ref] wrote:

quoted

On Fri, Jun 14, 2019 at 10:13:20PM +0530, Jagan Teki wrote:

quoted

TCON TOP have clock gates for TV0, TV1, dsi and right
now these are register during bind call.

Of which, dsi clock gate would required during DPHY probe
but same can miss to get since tcon top is not bound at
that time.

To solve, this circular dependency move the clock gate
registration from bind to probe so-that DPHY can get the
dsi gate clock on time.

It's not really clear to me what the circular dependency is?

if you have a chain that is:

tcon-top +-> DSI
         +-> D-PHY

There's no loop, right?

Looking at how the DTSI patch structures things (without going into
whether it is correct or accurate):

The D-PHY is not part of the component graph. However it requests
the DSI gate clock from the TCON-TOP.

The TCON-TOP driver, in its current form, only registers the clocks
it provides at component bind time. Thus the D-PHY can't successfully
probe until the TCON-TOP has been bound.

The DSI interface requires the D-PHY to bind. It will return -EPROBE_DEFER
if it cannot request it. This in turn goes into the error path of
component_bind_all, which unbinds all previous components.

So it's actually

    D-PHY -> TCON-TOP -> DSI
      ^                   |
      |--------------------

I've not checked, but I suspect there's no possibility of having other
drivers probe (to deal with deferred probing) within component_bind_all.
Otherwise we shouldn't run into this weird circular dependency issue.

So the question for Jagan is that is this indeed the case? Does this
patch solve it, or at least work around it.

Yes, this is what I was mentioned in initial version, since the "dsi"
gate in tcon top is registering during bind, the dphy of dsi
controller won't get the associated clock for "mod" so it is keep on
returning -EPROBE_DEFER. By moving the clock gate registration to
probe, everything bound as expected.

I believe you failed to mention the DSI block, which is the part that
completes the circular dependency. Don't expect others to have full
awareness of the context. You have to provide it in your commit log.

I have mentioned DPHY and yes it is possible to give more information
will update in next version, no problem. thanks for mentioning that.

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