linux-kernel - Re: [PATCH v4 2/3] dt-bindings: usb: dwc3: Add snps,host-vbus-glitches-quirk avoid vbus glitch

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Date: Tue, 30 Jan 2024 14:25:43 -0500
From: Frank Li <Frank.li@....com>
To: Conor Dooley <conor@...nel.org>
Cc: thinh.nguyen@...opsys.com, balbi@...nel.org, devicetree@...r.kernel.org,
	gregkh@...uxfoundation.org, imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	mark.rutland@....com, mathias.nyman@...el.com, pku.leo@...il.com,
	ran.wang_1@....com, robh+dt@...nel.org,
	sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v4 2/3] dt-bindings: usb: dwc3: Add
 snps,host-vbus-glitches-quirk avoid vbus glitch

On Tue, Jan 30, 2024 at 06:28:25PM +0000, Conor Dooley wrote:
> Hey,
> 
> This version seems to be the lastest (v4) for this binding, but went out
> prior to discussion actually finishing on the v1!! of this patch, even
> ignoring Rob's comment today.
> Please wait for conversations to resolve before sending new versions.
> I, at least, do not get paid for what I do here, so I often need well
> more than a day before I can get around to clearing my review queue.
> On Wed, Jan 24, 2024 at 10:25:24AM -0500, Frank Li wrote:
> 
> > From: Ran Wang <ran.wang_1@....com>
> > 
> > When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS
> > (or its control signal) will turn on immediately on related Root Hub
> > ports. Then the VBUS will be de-asserted for a little while during xhci
> > reset (conducted by xhci driver) for a little while and back to normal.
> > 
> > This VBUS glitch might cause some USB devices emuration fail if kernel
> > boot with them connected. One SW workaround which can fix this is to
> > program all PORTSC[PP] to 0 to turn off VBUS immediately after setting
> > host mode in DWC3 driver(per signal measurement result, it will be too
> > late to do it in xhci-plat.c or xhci.c).
> > 
> > Signed-off-by: Ran Wang <ran.wang_1@....com>
> > Reviewed-by: Peter Chen <peter.chen@....com>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> 
> Where is your changelog?

Sorry forget add it this patch.

> 
> >  Documentation/devicetree/bindings/usb/snps,dwc3.yaml | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
> > index 203a1eb66691f..8f5d250070c78 100644
> > --- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
> > +++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
> > @@ -273,6 +273,13 @@ properties:
> >        with an external supply.
> >      type: boolean
> >  
> > +  snps,host-vbus-glitches-quirk:
> 
> I specifically recall saying no to adding "-quirk" here, but that
> might've been after this patch was sent.

Your comment is at v0 version. I told you there are v4. 

> 
> > +    description:
> > +      When set, power off all Root Hub ports immediately after
> > +      setting host mode to avoid vbus (negative) glitch happen in later
> > +      xhci reset. And the vbus will back to 5V automatically when reset done.
> > +    type: boolean
> 
> Rob commented today on the v1 conversation:
> https://lore.kernel.org/all/20240130181322.GA2079185-robh@kernel.org/
> 
> Please respond (there) to his comment.

Okay I will reply at v1 thread.

> 
> Thanks,
> Conor.
> 
> >    snps,is-utmi-l1-suspend:
> >      description:
> >        True when DWC3 asserts output signal utmi_l1_suspend_n, false when
> > -- 
> > 2.34.1
> >