[PATCH v2] usb: check for companion controller in uclass

[Marek Vasut]

On 9/1/23 14:12, Fabrice Gasnier wrote:
> On 9/1/23 12:48, Marek Vasut wrote:
>> On 9/1/23 11:52, Fabrice Gasnier wrote:
>>> EHCI is usually used with companion controller (like OHCI) as companion
>>> controller. This information on the companion is missing currently in
>>> companion drivers.
>>> So, if the usb-uclass isn't aware, it may scan busses in any order: OHCI
>>> first, then EHCI.
>>> This is seen on STM32MP1 where DT probing makes the probe order to occur
>>> by increasing address (OHCI address < EHCI address).
>>>
>>> When a low speed or full-speed device is plugged in, it's not detected as
>>> EHCI should first detect it, and give ownership (handover) to OHCI.
>>>
>>> Current situation on STM32MP1 (with a low speed device plugged-in)
>>> STM32MP> usb start
>>> starting USB...
>>> Bus usb at 5800c000: USB OHCI 1.0
>>> Bus usb at 5800d000: USB EHCI 1.00
>>> scanning bus usb at 5800c000 for devices... 1 USB Device(s) found
>>> scanning bus usb at 5800d000 for devices... 1 USB Device(s) found
>>>      scanning usb for storage devices... 0 Storage Device(s) found
>>>
>>> The "companion" property in the device tree allow to retrieve companion
>>> controller information, from the EHCI node. This allow marking the
>>> companion driver as such.
>>>
>>> With this patch (same low speed device plugged in):
>>> STM32MP> usb start
>>> starting USB...
>>> Bus usb at 5800c000: USB OHCI 1.0
>>> Bus usb at 5800d000: USB EHCI 1.00
>>> scanning bus usb at 5800d000 for devices... 1 USB Device(s) found
>>> scanning bus usb at 5800c000 for devices... 2 USB Device(s) found
>>>      scanning usb for storage devices... 0 Storage Device(s) found
>>> STM32MP> usb tree
>>> USB device tree:
>>> 1  Hub (12 Mb/s, 0mA)
>>> |   U-Boot Root Hub
>>> |
>>> +-2  Human Interface (1.5 Mb/s, 100mA)
>>>      HP HP USB 1000dpi Laser Mouse
>>>
>>> 1  Hub (480 Mb/s, 0mA)
>>>    u-boot EHCI Host Controller
>>>
>>> This also optimize bus scan when a High speed device is plugged in, as
>>> the usb-uclass skips OHCI in this case:
>>>
>>> STM32MP> usb reset
>>> resetting USB...
>>> Bus usb at 5800c000: USB OHCI 1.0
>>> Bus usb at 5800d000: USB EHCI 1.00
>>> scanning bus usb at 5800d000 for devices... 2 USB Device(s) found
>>>      scanning usb for storage devices... 1 Storage Device(s) found
>>> STM32MP> usb tree
>>> USB device tree:
>>> 1  Hub (480 Mb/s, 0mA)
>>> |  u-boot EHCI Host Controller
>>> |
>>> +-2  Mass Storage (480 Mb/s, 200mA)
>>>      SanDisk Cruzer Blade 03003432021922011407
>>>
>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier at foss.st.com>
>>> ---
>>>
>>> Changes in v2:
>>> - move companion probing from generic ehci driver to usb-uclass, after
>>>     Marek's questions on design choice.
>>> - rename commit title to follow this change
>>>
>>> ---
>>>    drivers/usb/host/usb-uclass.c | 36 +++++++++++++++++++++++++++++++++++
>>>    1 file changed, 36 insertions(+)
>>>
>>> diff --git a/drivers/usb/host/usb-uclass.c
>>> b/drivers/usb/host/usb-uclass.c
>>> index 02c0138a2065..e238eee8c84d 100644
>>> --- a/drivers/usb/host/usb-uclass.c
>>> +++ b/drivers/usb/host/usb-uclass.c
>>> @@ -249,6 +249,37 @@ static void remove_inactive_children(struct
>>> uclass *uc, struct udevice *bus)
>>>        }
>>>    }
>>>    +static int usb_probe_companion(struct udevice *bus)
>>> +{
>>> +    struct udevice *companion_dev;
>>> +    int ret;
>>> +
>>> +    /*
>>> +     * Enforce optional companion controller is marked as such in
>>> order to
>>> +     * 1st scan the primary controller, before the companion controller
>>> +     * (ownership is given to companion when low or full speed devices
>>> +     * have been detected).
>>> +     */
>>> +    ret = uclass_get_device_by_phandle(UCLASS_USB, bus, "companion",
>>> &companion_dev);
>>> +    if (!ret) {
>>> +        struct usb_bus_priv *companion_bus_priv;
>>> +
>>> +        debug("%s is the companion of %s\n", companion_dev->name,
>>> bus->name);
>>> +        companion_bus_priv = dev_get_uclass_priv(companion_dev);
>>> +        companion_bus_priv->companion = true;
>>> +    } else if (ret && ret != -ENOENT && ret != -ENODEV) {
>>> +        /*
>>> +         * Treat everything else than no companion or disabled
>>> +         * companion as an error. (It may not be enabled on boards
>>> +         * that have a High-Speed HUB to handle FS and LS traffic).
>>> +         */
>>> +        printf("Failed to get companion (ret=%d)\n", ret);
>>> +        return ret;
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>>    int usb_init(void)
>>>    {
>>>        int controllers_initialized = 0;
>>> @@ -299,6 +330,11 @@ int usb_init(void)
>>>                printf("probe failed, error %d\n", ret);
>>>                continue;
>>>            }
>>> +
>>> +        ret = usb_probe_companion(bus);
>>
>> Shouldn't this ^ be in separate uclass_foreach_dev(bus, uc) {} loop
>> before this device_probe() loop , so that when the probe of the
>> controller is called, its ->companion is already set ?
> 
> The point is to have the companion flag set before scanning the bus.
> Generic OHCI or EHCI drivers don't care about this flag.
> 
> Scanning is performed right after this first loop (low-level), in two
> subsequent steps: primary controllers (2nd step), then companions if
> necessary (3rd step).

Thanks for clarifying, in that case:

Reviewed-by: Marek Vasut <marex at denx.de>

Is this a fix for this release (currently rc3) or next release ?