linux-kernel - Re: [RFC PATCH v2 0/2] usb: typec: Add driver for Microchip sama7g5 tcpc

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Message-ID: <b42ddee2-1006-7e46-2df8-156c14c3a2e0@microchip.com>
Date:   Wed, 31 Mar 2021 19:41:15 +0000
From:   <Cristian.Birsan@...rochip.com>
To:     <gregkh@...uxfoundation.org>
CC:     <linux@...ck-us.net>, <heikki.krogerus@...ux.intel.com>,
        <robh+dt@...nel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [RFC PATCH v2 0/2] usb: typec: Add driver for Microchip sama7g5
 tcpc



On 3/31/21 9:21 AM, Greg KH wrote:
> 
> On Tue, Mar 30, 2021 at 11:54:40PM +0300, cristian.birsan@...rochip.com wrote:
>> From: Cristian Birsan <cristian.birsan@...rochip.com>
>>
>> This patch set adds initial driver support for Microchip USB Type-C Port
>> Controller (TCPC) embedded in sama7g5 SoC.
>>
>> The controller does not implement power delivery and the driver uses dummy
>> functions to register the port with TCPM. The current silicon version is
>> not able to trigger interrupts so the driver will poll for changes on
>> CC1/CC2 lines.
>>
>> Support for sink is implemented and tested with an USB device. The plan is
>> to extend the driver and add source support.
> 
> Why are these marked "RFC"?

I sent the patch as RFC because I wanted to gather feedback on it and on how
it fits under Type-C/TCPM subsystem.

> 
> Do you really not think they should be accepted?  Why not, what is left
> to do with them?
> 

I think the driver can be merged after I address the review received on the
mailing list. At the same time, I plan to enhance it with the following:

- add sink detection at power source and check it with USB Host.

- add a way to notify VBUS presence back to USB gadget.  As TCPC needs to
detect VBUS and report it to TCPM, I moved the VBUS detection gpio from the
USB gadget device tree node to TCPC. For now, the gadget always assumes that
VBUS is on. I saw that some USB PHY drivers use a notifier chain. I can
implement something similar.
  
> I do not normally review "RFC" patches as the authors do not think they
> should be merged, and we have plenty of patches that are being asked to
> be merged already :)

Until now I received a review from Heikki Krogerus. I will let this version
of the patch on the mailing list for some time in case there is additional
feedback.

> 
> thanks,
> 
> greg k-h
> 

Regards,
Cristian