linux-kernel - RE: [PATCH v2 1/2] dt-bindings: usb: dwc3-xilinx: Add documentation for Versal DWC3 Controller

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Date:   Fri, 25 Sep 2020 06:07:02 +0000
From:   Manish Narani <MNARANI@...inx.com>
To:     Felipe Balbi <balbi@...nel.org>, Rob Herring <robh@...nel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Michal Simek <michals@...inx.com>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        git <git@...inx.com>
Subject: RE: [PATCH v2 1/2] dt-bindings: usb: dwc3-xilinx: Add documentation
 for Versal DWC3 Controller

Hi Rob/Felipe,

Thanks for the review.

> -----Original Message-----
> From: Felipe Balbi <balbi@...nel.org>
> Sent: Thursday, September 24, 2020 12:47 PM
> To: Rob Herring <robh@...nel.org>; Manish Narani <MNARANI@...inx.com>
> Cc: gregkh@...uxfoundation.org; Michal Simek <michals@...inx.com>;
> p.zabel@...gutronix.de; linux-usb@...r.kernel.org;
> devicetree@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org; git <git@...inx.com>
> Subject: Re: [PATCH v2 1/2] dt-bindings: usb: dwc3-xilinx: Add
> documentation for Versal DWC3 Controller
> 
> Rob Herring <robh@...nel.org> writes:
> 
> > On Thu, Sep 10, 2020 at 12:33:04AM +0530, Manish Narani wrote:
> >> Add documentation for Versal DWC3 controller. Add required property
> >> 'reg' for the same. Also add optional properties for snps,dwc3.
> >>
> >> Signed-off-by: Manish Narani <manish.narani@...inx.com>
> >> ---
> >>  .../devicetree/bindings/usb/dwc3-xilinx.txt   | 20 +++++++++++++++++--
> >>  1 file changed, 18 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/usb/dwc3-xilinx.txt
> b/Documentation/devicetree/bindings/usb/dwc3-xilinx.txt
> >> index 4aae5b2cef56..219b5780dbee 100644
> >> --- a/Documentation/devicetree/bindings/usb/dwc3-xilinx.txt
> >> +++ b/Documentation/devicetree/bindings/usb/dwc3-xilinx.txt
> >> @@ -1,7 +1,8 @@
> >>  Xilinx SuperSpeed DWC3 USB SoC controller
> >>
> >>  Required properties:
> >> -- compatible:	Should contain "xlnx,zynqmp-dwc3"
> >> +- compatible:	May contain "xlnx,zynqmp-dwc3" or "xlnx,versal-
> dwc3"
> >> +- reg:		Base address and length of the register control block
> >>  - clocks:	A list of phandles for the clocks listed in clock-names
> >>  - clock-names:	Should contain the following:
> >>    "bus_clk"	 Master/Core clock, have to be >= 125 MHz for SS
> >> @@ -13,12 +14,24 @@ Required child node:
> >>  A child node must exist to represent the core DWC3 IP block. The name of
> >>  the node is not important. The content of the node is defined in dwc3.txt.
> >>
> >> +Optional properties for snps,dwc3:
> >> +- dma-coherent:	Enable this flag if CCI is enabled in design. Adding this
> >> +		flag configures Global SoC bus Configuration Register and
> >> +		Xilinx USB 3.0 IP - USB coherency register to enable CCI.
> >> +- snps,enable-hibernation: Add this flag to enable hibernation support
> for
> >> +		peripheral mode.
> >
> > This belongs in the DWC3 binding. It also implies that hibernation is
> > not supported by any other DWC3 based platform. Can't this be implied by
> > the compatible string (in the parent)?

Rob, We can move this to dwc3 bindings. If Felipe is okay with below response.

> 
> hibernation support is detectable in runtime, and we've been using that.

Felipe, Yes, this flag is to control the enable/disable hibernation.
I did not see has_hibernation flag being set anywhere in the driver.
Can we control the hibernation enable/disable through DT entry? See below:
-----
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 2eb34c8b4065..1baf44d8d566 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -769,8 +769,15 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc)
                        reg &= ~DWC3_GCTL_DSBLCLKGTNG;
                break;
        case DWC3_GHWPARAMS1_EN_PWROPT_HIB:
-               /* enable hibernation here */
-               dwc->nr_scratch = DWC3_GHWPARAMS4_HIBER_SCRATCHBUFS(hwparams4);
+               if (!device_property_read_bool(dwc->dev,
+                                              "snps,enable-hibernation")) {
+                       dev_dbg(dwc->dev, "Hibernation not enabled\n");
+               } else {
+                       /* enable hibernation here */
+                       dwc->nr_scratch =
+                               DWC3_GHWPARAMS4_HIBER_SCRATCHBUFS(hwparams4);
+                       dwc->has_hibernation = 1;
+               }

                /*
                 * REVISIT Enabling this bit so that host-mode hibernation
-----

Please provide your inputs.

Thanks,
Manish