On 30 March 2016 at 10:05, Peter Chen [off-list ref] wrote:

On Tue, Mar 29, 2016 at 10:23:14AM -0700, Mark Brown wrote:

quoted

On Mon, Mar 28, 2016 at 03:13:51PM +0800, Peter Chen wrote:

quoted

On Mon, Mar 28, 2016 at 02:51:40PM +0800, Baolin Wang wrote:

quoted

quoted

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I am afraid I still not find the user (udc driver) for this framework, I would
like to see how udc driver block the enumeration until the charger detection
has finished, or am I missing something?

quoted

quoted

It is not for udc driver but for power users who want to negotiate
with USB subsystem.

quoted

Then, where is the code the test user to decide what kinds of USB charger
(SDP, CDP, DCP) is connecting now?

Even without detection of CDP and DCP we have configurability within SDP
- there's the 2.5mA suspended limit, the 100mA default limit and the
higher 500mA limit which can be negotiated.

Well, things may be a little complicated.

I try to address your comments, maybe Mark need to do some complements. Thanks.

- First, how to design get_charger_type for each udc driver?
Since the charger detection process affects dp/dm signal, it can't be done
during the enumeration or after that. So, the detection process can be only
done after vbus has detected and before udc pull up dp.

Then, when the get_charger_type do real charger detection? My suggestion is,
if the charger type is unknown, we do real one, else, we just return the
stored type value.

I think that is why we let udc driver to implement the
'gadget->ops->get_charger_type()' callback, which can be controlled by
udc driver.

- Second, When to notify charger IC to charger:
For SDP and CDP, it needs to notify charger IC after set configuration
has finished.
For DCP (and ACA, I am not sure), can notify charger IC after charger
detection has finished or later.

So, when we get charger is present, we need to notify charger IC at once
for DCP (and ACA); But for SDP and CDP, we need to let the gadget
composite core to notify charger IC after set configuration has finished,
like the patch 2/4 does.

But mostly charger IC is separate with gadget, so the charger IC
doesn't need to worry about the gadget status.

- Third, since composite driver covers 500mA (and more for CDP) after set
configuration and 2mA after suspend, and vbus handler covers connect
and disconnect. I can't see any reasons we need to notify gadget state
for power driver, do we really need to have usb_charger_plug_by_gadget?

In some solutions, gadget does not negotiate with the current. They
just send out one signal to power driver to set the current when the
gadget state is changed (plugin or not). So we need to check the
charger state by the gadget state to notify the charger IC to set
current.

--
Best Regards,
eter Chen

-- 
Baolin.wang
Best Regards
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