Re: [PATCH v1 5/8] usb: chipidea: tegra: Support host mode

Dmitry Osipenko
2020-12-16T09:54:38Z

16.12.2020 12:32, Peter Chen пишет:
>
>>>>
>>>> struct tegra_usb_soc_info {
>>>> unsigned long flags;
>>>> + unsigned int txfifothresh;
>>>> + enum usb_dr_mode dr_mode;
>>>> +};
>>>> +
>>>> +static const struct tegra_usb_soc_info tegra20_ehci_soc_info = {
>>>> + .flags = CI_HDRC_REQUIRES_ALIGNED_DMA |
>>>> + CI_HDRC_OVERRIDE_PHY_CONTROL,
>>>> + .dr_mode = USB_DR_MODE_HOST,
>>>> + .txfifothresh = 10,
>>>> +};
>>>> +
>>>> +static const struct tegra_usb_soc_info tegra30_ehci_soc_info = {
>>>> + .flags = CI_HDRC_REQUIRES_ALIGNED_DMA |
>>>> + CI_HDRC_OVERRIDE_PHY_CONTROL
>>>> + .dr_mode = USB_DR_MODE_HOST,
>>>> + .txfifothresh = 16,
>>>> };
>>>>
>>>> static const struct tegra_usb_soc_info tegra_udc_soc_info = {
>>>> - .flags = CI_HDRC_REQUIRES_ALIGNED_DMA,
>>>> + .flags = CI_HDRC_REQUIRES_ALIGNED_DMA |
>>>> + CI_HDRC_OVERRIDE_PHY_CONTROL,
>>>> + .dr_mode = USB_DR_MODE_UNKNOWN,
>>>> };
>>>
>>> What's the usage for this dr_mode? Does these three SoCs only supports
>>> single mode, it usually sets dr_mode at board dts file to indicate USB
>>> role for this board.
>>
>> All Tegra SoCs have three USB controllers. Only one of these three controllers
>> supports peripheral / OTG modes, the other two controllers are fixed to the
>> host mode and device trees do not specify the dr_mode for the host
>> controllers.
>>
>> Hence we need to enforce the dr_mode=host for the host-mode controllers.
>>
>> For UDC the default mode is "unknown" because actual mode comes from a
>> board's device tree.
>>
>
> You could add dr_mode property at usb node of soc.dtsi to fulfill that.

This will break older DTBs, we can't do this.

...
>>>> static int ehci_ci_portpower(struct usb_hcd *hcd, int portnum, bool
>>>> enable) {
>>>> struct ehci_hcd *ehci = hcd_to_ehci(hcd); @@ -160,14 +166,14 @@
>>>> static int host_start(struct ci_hdrc *ci)
>>>> pinctrl_select_state(ci->platdata->pctl,
>>>> ci->platdata->pins_host);
>>>>
>>>> + ci->hcd = hcd;
>>>> +
>>>> ret = usb_add_hcd(hcd, 0, 0);
>>>> if (ret) {
>>>> goto disable_reg;
>>>> } else {
>>>> struct usb_otg *otg = &ci->otg;
>>>>
>>>> - ci->hcd = hcd;
>>>> -
>>>
>>> Why this changed?
>>
>> The ci->hcd is used by tegra_usb_notify_event() to handle reset event and the
>> reset happens once usb_add_hcd() is invoked. Hence we need to pre-assign
>> the hcd pointer, otherwise there will be a NULL dereference.
>
> Get it, please set ci->hcd as NULL at error path.

Ok, thanks.