> -----Original Message-----
> From: Francesco Dolcini <francesco@xxxxxxxxxx>
> Sent: Thursday, November 3, 2022 1:59 AM
> To: Jun Li <jun.li@xxxxxxx>
> Cc: Francesco Dolcini <francesco@xxxxxxxxxx>; Jun Li (OSS)
> <jun.li@xxxxxxxxxxx>; Peter Chen <peter.chen@xxxxxxxxxx>;
> linux-usb@xxxxxxxxxxxxxxx; Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Sascha
> Hauer <s.hauer@xxxxxxxxxxxxxx>; Pengutronix Kernel Team
> <kernel@xxxxxxxxxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; dl-linux-imx
> <linux-imx@xxxxxxx>; Felipe Balbi <balbi@xxxxxxxxxx>;
> philippe.schenker@xxxxxxxxxxx; Francesco Dolcini
> <francesco.dolcini@xxxxxxxxxxx>
> Subject: Re: USB runtime PM issues on i.MX6ULL
>
> On Wed, Nov 02, 2022 at 10:12:42AM +0000, Jun Li wrote:
> > > > On Tue, Nov 01, 2022 at 03:10:46AM +0000, Jun Li wrote:
> > > > > > On Mon, Oct 31, 2022 at 01:40:39PM +0000, Jun Li (OSS) wrote:
> > > > > > > > I am debugging some unexpected USB behavior on a i.MX6ULL SOC,
> > > > > > > > chipidea controller ("fsl,imx6ul-usb") and a fsl mxs usbphy
> > > > > > > > ("fsl,imx6ul-usbphy").
> > > > > > > >
> > > > > > > > The HW design has 2 USB interface, the first one is dual-role,
> > > > > > > > while the second one is a host port with NO way to re-read
> the
> > > > > > > > VBUS (USB_OTG2_VBUS is not really connected, there is just
> a
> > > > > > > > capacitor to GND).
> > > > > > >
> > > > > > > How is your USB_OTG1_VBUS status? Can you try to make your
> > > > > > > USB_OTG1_VBUS pad has a valid VBUS voltage, then run your Host
> > > > > > > only port test with runtime PM enabled?
> > > > > >
> > > > > > USB_OTG1_VBUS is tied to GND the same way as USB_OTG2_VBUS, not
> > > > > > really straightforward to do such a test.
> > > > >
> > > > > iMX6ULL need at least one valid VBUS(either from OTG1 or OTG2) as
> > > > > input to power the internal USB LDO if I understand correctly.
> > > > This surprise me a little bit, since
> > > > - the i.MX6ULL datasheet prescribe to keep the VBUS disconnected if
> > > > unused
> > >
> > > I think "unused" here means you do not need/enable the port at all.
> > >
> > > > - downstream NXP kernel seems to work fine ("seems" since we do have
> > > > some patches there, so I could be wrong)
> > >
> > > What do you mean by " downstream NXP kernel seems to work fine"?
> > > The downstream kernel can work on your HW? But upstream kernel
> > > driver does not?
>
> Correct, NXP downstream kernel is working fine, upstream kernel requires
> runtime PM disabled to work correctly.
>
> > > > - disabling runtime pm on upstream Linux kernel make it works
> > > > perfectly, so there is a way in SW to have this HW configuration
> > > > working.
> > >
> > > Again I want to make sure the both VBUS pads(OTG1 and OTG2) voltage
> > > are always at 0v on your HW, can you double check and confirm?
> > > I ask this again because such situation should cause the USB port
> > > Cannot work at any cases, but your current status is: only low
> > > power wakeup cannot work.
> >
> > Could you please check the voltage of pad of VDD_USB_CAP on your HW?
>
> I was about to clarify you this point, it's important and I forgot about
> it, sorry about that!
>
> VDD_USB_CAP in our design is connected to a 3.0V external LDO, voltage
> on both VBUS pads is 0V (FYI: this specific hardware design was validated
> by NXP hardware engineers).
Then the HW design should be fine.
I need find time to try the upstream kernel on my iMX6ULL board to check
this.
Li Jun
>
> Francesco
