Re: [PATCH v2 2/2] phy: qcom-usb-hs: Add qcom,dp-manual-pullup logic

[Bryan O'Donoghue]

On 29/12/2022 21:02, Stephan Gerhold wrote:
> On Thu, Dec 29, 2022 at 08:45:15PM +0100, Stephan Gerhold wrote:
> > On Thu, Dec 29, 2022 at 06:34:10PM +0000, Bryan O'Donoghue wrote:
> > > Downstream has a flag called qcom,dp-manual-pullup which informs the
> > > downstream driver if it should toggle ULPI_MISC_A_VBUSVLDEXTSEL and
> > > ULPI_MISC_A_VBUSVLDEXT.
> > >
> > > Downstream states:
> > >
> > > "qcom,dp-manual-pullup: If present, vbus is not routed to USB
> > >          controller/phy and controller driver therefore enables pull-up
> > >          explicitly before starting controller using usbcmd run/stop bit."
> > >
> > > Working with a system that has both an external Type-C port controller and
> > > an internal USB Hub results in a situation where VBUS is not connected to
> > > the SoC.
> > >
> > > In this case we still need to set the DP pullup.
> > >
> > > This patch enables and disables the DP pullup on PHY power_on and power_off
> > > respectively if the DT has declared the bool "qcom,enable-vbus-pullup"
> > > effectively replicating the downstream logic to the same effect.
> > >
> > > Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
> > [...]
> >
> > An alternative that I've occasionally used for early bring-up is to
> > simply use a dummy extcon driver [1] that permanently reports active
> > VBUS. The end result is the same. While it's clearly a hack perhaps this
> > makes it a bit more clear that ideally you really should try to assign
> > an extcon device, to avoid keeping the USB controller and PHY on
> > permanently.
>
> BTW another nice trick that should work in all almost all cases is to
> use the state of the PMIC USB_IN pin as VBUS detection. All battery-
> powered devices I have seen route the USB VBUS to PM8916 USB_IN. And
> even many boards like DB410c seem to do that or at least permanently
> supply 5V there. In all these cases the &pm8916_usbin extcon will
> report a VBUS state that should make USB work.
>
> Have you tried using that on your MSM8939 board with the Type-C setup?
>
> &pm8916_usbin {
> 	status = "okay";
> };
>
> &usb {
> 	status = "okay";
> 	usb-role-switch;
> 	extcon = <&pm8916_usbin>;
> };
>
> &usb_hs_phy {
> 	extcon = <&pm8916_usbin>;
> };
>
> Stephan

I checked USBIN before my last email reply.

Its possible its connected but its not there on the 8939 schematic I have.

---
bod