Re: [PATCH 7/8] usb: dwc3: qcom: Start USB in 'host mode' on the SDM845

Lee Jones
2019-06-05T08:34:59Z

On Wed, 05 Jun 2019, Bjorn Andersson wrote:

> On Tue 04 Jun 03:44 PDT 2019, Lee Jones wrote:
>
> > When booting with Device Tree, the current default boot configuration
> > table option, the request to boot via 'host mode' comes from the
> > "dr_mode" property.
>
> This has been the default on the MTP, but this is changing as this is
> causing issues when connected downstream from a hub (the typical
> development case for the primary USB port of a phone like device) and
> more importantly we don't have support for the PMIC blocks that control
> VBUS.

My point is not about which mode is currently chosen. It's more about
the capability of choosing which mode is appropriate for a given
system via DT.

> Once these issues are resolved the dr_mode would be "otg".

OTG doesn't work on this H/W, so we need to specify "host" mode.

> > A property of the same name can be used inside
> > ACPI tables too. However it is missing from the SDM845's ACPI tables
> > so we have to supply this information using Platform Device Properites
> > instead.
> >
>
> Afaict this would install a fall-back property, so in the case that we
> have specified dr_mode in DT (or ACPI) that would take precedence. So

That's correct.

> the commit message should reflect that this redefines the default choice
> to be "host", rather than "otg".

No problem.

> Which is in conflict with what's described for dr_mode in
> Documentation/devicetree/bindings/usb/generic.txt

This implementation only affects ACPI based platforms. When booting
with DT, the description in that DT related document is still
accurate.

> And this driver is used on a range of different Qualcomm platforms, so I
> don't think this is SDM845 specific.

ACPI based platforms?

All the ones I've seen use the XHCI USB driver directly ("PNP0D10").

> > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > ---
> > drivers/usb/dwc3/dwc3-qcom.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> > index 349bf549ee44..f21fdd6cdd1a 100644
> > --- a/drivers/usb/dwc3/dwc3-qcom.c
> > +++ b/drivers/usb/dwc3/dwc3-qcom.c
> > @@ -468,6 +468,11 @@ static const struct acpi_device_id dwc3_qcom_acpi_match[] = {
> > };
> > MODULE_DEVICE_TABLE(acpi, dwc3_qcom_acpi_match);
> >
> > +static const struct property_entry dwc3_qcom_acpi_properties[] = {
> > + PROPERTY_ENTRY_STRING("dr_mode", "host"),
> > + {}
> > +};
> > +
> > static int dwc3_qcom_probe(struct platform_device *pdev)
> > {
> > struct device_node *np = pdev->dev.of_node, *dwc3_np;
> > @@ -603,6 +608,13 @@ static int dwc3_qcom_probe(struct platform_device *pdev)
> > goto platform_unalloc;
> > }
> >
> > + ret = platform_device_add_properties(qcom->dwc3,
> > + dwc3_qcom_acpi_properties);
> > + if (ret < 0) {
> > + dev_err(&pdev->dev, "failed to add properties\n");
> > + goto platform_unalloc;
> > + }
> > +
> > ret = platform_device_add(qcom->dwc3);
> > if (ret) {
> > dev_err(&pdev->dev, "failed to add device\n");

--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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