linux-kernel - Re: [PATCH 3/3] usb: dwc3: gadget: Add support for disabling U1 and U2 entries

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Date:   Mon, 6 May 2019 20:58:27 +0000
From:   "Claus H. Stovgaard" <cst@...seone.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Anurag Kumar Vulisha <anurag.kumar.vulisha@...inx.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Felipe Balbi <balbi@...nel.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "v.anuragkumar@...il.com" <v.anuragkumar@...il.com>
Subject: Re: [PATCH 3/3] usb: dwc3: gadget: Add support for disabling U1 and
 U2 entries

Hi Thinh and Anurag

On man, 2019-05-06 at 19:21 +0000, Thinh Nguyen wrote:

> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index a1b126f..4f0912c 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1285,6 +1285,10 @@ static void dwc3_get_properties(struct dwc3
> > *dwc)
> >  				"snps,dis_u2_susphy_quirk");
> >  	dwc->dis_enblslpm_quirk = device_property_read_bool(dev,
> >  				"snps,dis_enblslpm_quirk");
> > +	dwc->dis_u1_entry_quirk = device_property_read_bool(dev,
> > +				"snps,dis_u1_entry_quirk");
> > +	dwc->dis_u2_entry_quirk = device_property_read_bool(dev,
> > +				"snps,dis_u2_entry_quirk");
> 
> Please use "-" rather than "_" in the property names.

I have thought about this feature over the weekend, and think the
naming should be changed to something like "snps,bos-u1-exit-lat-in-us" 
and named the same in the code. And then be the value used by the
get_config_params. E.g. the device-tree is used to set the values
directly used for bUxdevExitLat instead of named something not related
to exit latency.

With this the name and function is a 1 to 1 match, and you can among
others set it to 0 for optaining what Anurag wants.

Regarding the disabling of U1 / U2. I send this to Anurag
https://marc.info/?l=linux-usb&m=155683299311954&w=2
Here i created a configfs interface with the names "lpm_U1_disable" and
"lpm_U2_disable" for controlling the DTCL of dwc3, and reject
SET_FEATURE(U1/U2)

Will send this in seperate patch tomorrow, in the hope that Anurags
feature can become a way for controlling exit latency, and my patch
become a way for disabling U1/U2

BR
Claus