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    SubjectRe: [PATCH v2] usb: core: hub: Add quirks for reducing device address timeout
    On Mon, Oct 09, 2023 at 06:14:02PM +0200, Hardik Gajjar wrote:
    > Currently, the timeout for the set address command is fixed at
    > 5 seconds in the xhci driver. This means the host waits up to 5
    > seconds to receive a response for the set_address command from
    > the device.
    >
    > In the automotive context, most smartphone enumerations, including
    > screen projection, should ideally complete within 3 seconds.
    > Achieving this is impossible in scenarios where the set_address is
    > not successful and waits for a timeout.
    >
    > The shortened address device timeout quirks provide the flexibility
    > to align with a 3-second time limit in the event of errors.
    > By swiftly triggering a failure response and swiftly initiating
    > retry procedures, these quirks ensure efficient and rapid recovery,
    > particularly in automotive contexts where rapid smartphone enumeration
    > and screen projection are vital.

    So you have known-broken devices where you want a shorter error timeout?
    But you don't list those devices in this patch adding the quirk
    settings, shouldn't that be required, otherwise this looks like an
    unused quirk.

    > The quirk will set the timeout to 500 ms from 5 seconds.
    >
    > To use the quirk, please write "vendor_id:product_id:p" to
    > /sys/bus/usb/drivers/hub/module/parameter/quirks
    >
    > For example,
    > echo "0x2c48:0x0132:p" > /sys/bus/usb/drivers/hub/module/parameter/quirks"
    >
    > Signed-off-by: Hardik Gajjar <hgajjar@de.adit-jv.com>
    > ---
    > changes since version 1:
    > - implement quirk instead of new API in xhci driver
    > ---
    > drivers/usb/core/hub.c | 15 +++++++++++++--
    > drivers/usb/core/quirks.c | 3 +++
    > drivers/usb/host/xhci-mem.c | 1 +
    > drivers/usb/host/xhci-ring.c | 3 ++-
    > drivers/usb/host/xhci.c | 9 +++++----
    > drivers/usb/host/xhci.h | 1 +
    > include/linux/usb/hcd.h | 3 ++-
    > include/linux/usb/quirks.h | 3 +++
    > 8 files changed, 30 insertions(+), 8 deletions(-)
    >
    > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
    > index 3c54b218301c..975449b03426 100644
    > --- a/drivers/usb/core/hub.c
    > +++ b/drivers/usb/core/hub.c
    > @@ -54,6 +54,9 @@
    > #define USB_TP_TRANSMISSION_DELAY_MAX 65535 /* ns */
    > #define USB_PING_RESPONSE_TIME 400 /* ns */
    >
    > +#define USB_DEFAULT_ADDR_DEVICE_TIMEOUT (HZ * 5) /* 5000ms */
    > +#define USB_SHORT_ADDR_DEVICE_TIMEOUT 125 /* ~500ms */
    > +
    > /* Protect struct usb_device->state and ->children members
    > * Note: Both are also protected by ->dev.sem, except that ->state can
    > * change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
    > @@ -4626,8 +4629,16 @@ EXPORT_SYMBOL_GPL(usb_ep0_reinit);
    > static int hub_set_address(struct usb_device *udev, int devnum)
    > {
    > int retval;
    > + int timeout = USB_DEFAULT_ADDR_DEVICE_TIMEOUT;
    > struct usb_hcd *hcd = bus_to_hcd(udev->bus);
    >
    > + struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
    > +
    > + if (hub->hdev->quirks & USB_QUIRK_SHORT_DEVICE_ADDR_TIMEOUT)
    > + timeout = USB_SHORT_ADDR_DEVICE_TIMEOUT;
    > +
    > + dev_dbg(&udev->dev, "address_device timeout %d\n", timeout);

    Is this debugging code still needed?

    > /*
    > * The host controller will choose the device address,
    > * instead of the core having chosen it earlier
    > @@ -4639,11 +4650,11 @@ static int hub_set_address(struct usb_device *udev, int devnum)
    > if (udev->state != USB_STATE_DEFAULT)
    > return -EINVAL;
    > if (hcd->driver->address_device)
    > - retval = hcd->driver->address_device(hcd, udev);
    > + retval = hcd->driver->address_device(hcd, udev, timeout);
    > else
    > retval = usb_control_msg(udev, usb_sndaddr0pipe(),
    > USB_REQ_SET_ADDRESS, 0, devnum, 0,
    > - NULL, 0, USB_CTRL_SET_TIMEOUT);
    > + NULL, 0, jiffies_to_msecs(timeout));
    > if (retval == 0) {
    > update_devnum(udev, devnum);
    > /* Device now using proper address. */
    > diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
    > index 15e9bd180a1d..01ed26bd41f0 100644
    > --- a/drivers/usb/core/quirks.c
    > +++ b/drivers/usb/core/quirks.c
    > @@ -138,6 +138,9 @@ static int quirks_param_set(const char *value, const struct kernel_param *kp)
    > case 'o':
    > flags |= USB_QUIRK_HUB_SLOW_RESET;
    > break;
    > + case 'p':
    > + flags |= USB_QUIRK_SHORT_DEVICE_ADDR_TIMEOUT;
    > + break;
    > /* Ignore unrecognized flag characters */
    > }
    > }
    > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
    > index 8714ab5bf04d..492433fdac77 100644
    > --- a/drivers/usb/host/xhci-mem.c
    > +++ b/drivers/usb/host/xhci-mem.c
    > @@ -1729,6 +1729,7 @@ struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
    > }
    >
    > command->status = 0;
    > + command->timeout = 0;
    > INIT_LIST_HEAD(&command->cmd_list);
    > return command;
    > }
    > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
    > index 1dde53f6eb31..0bd19a1efdec 100644
    > --- a/drivers/usb/host/xhci-ring.c
    > +++ b/drivers/usb/host/xhci-ring.c
    > @@ -4301,7 +4301,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
    > /* if there are no other commands queued we start the timeout timer */
    > if (list_empty(&xhci->cmd_list)) {
    > xhci->current_cmd = cmd;
    > - xhci_mod_cmd_timer(xhci, XHCI_CMD_DEFAULT_TIMEOUT);
    > + xhci_mod_cmd_timer(xhci, (cmd->timeout) ? cmd->timeout :
    > + XHCI_CMD_DEFAULT_TIMEOUT);
    > }
    >
    > list_add_tail(&cmd->cmd_list, &xhci->cmd_list);
    > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
    > index e1b1b64a0723..1d088ceb2b74 100644
    > --- a/drivers/usb/host/xhci.c
    > +++ b/drivers/usb/host/xhci.c
    > @@ -4002,7 +4002,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
    > * SetAddress request to the device.
    > */
    > static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
    > - enum xhci_setup_dev setup)
    > + enum xhci_setup_dev setup, int timeout)

    What is the units of timeout here?

    > {
    > const char *act = setup == SETUP_CONTEXT_ONLY ? "context" : "address";
    > unsigned long flags;
    > @@ -4059,6 +4059,7 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
    > }
    >
    > command->in_ctx = virt_dev->in_ctx;
    > + command->timeout = timeout;
    >
    > slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
    > ctrl_ctx = xhci_get_input_control_ctx(virt_dev->in_ctx);
    > @@ -4185,14 +4186,14 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
    > return ret;
    > }
    >
    > -static int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
    > +static int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev, int timeout)
    > {
    > - return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ADDRESS);
    > + return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ADDRESS, timeout);
    > }
    >
    > static int xhci_enable_device(struct usb_hcd *hcd, struct usb_device *udev)
    > {
    > - return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ONLY);
    > + return xhci_setup_device(hcd, udev, SETUP_CONTEXT_ONLY, 0);

    0 is no timeout at all? Or max timeout? Where is this documented?

    And why is this only added to the xhci driver and not all other host
    controllers?

    > }
    >
    > /*
    > diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
    > index 7e282b4522c0..ebdca8dd01c2 100644
    > --- a/drivers/usb/host/xhci.h
    > +++ b/drivers/usb/host/xhci.h
    > @@ -818,6 +818,7 @@ struct xhci_command {
    > struct completion *completion;
    > union xhci_trb *command_trb;
    > struct list_head cmd_list;
    > + int timeout;

    What is the units here.

    > };
    >
    > /* drop context bitmasks */
    > diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
    > index 61d4f0b793dc..b0fda87ad3a2 100644
    > --- a/include/linux/usb/hcd.h
    > +++ b/include/linux/usb/hcd.h
    > @@ -373,7 +373,8 @@ struct hc_driver {
    > */
    > void (*reset_bandwidth)(struct usb_hcd *, struct usb_device *);
    > /* Returns the hardware-chosen device address */
    > - int (*address_device)(struct usb_hcd *, struct usb_device *udev);
    > + int (*address_device)(struct usb_hcd *, struct usb_device *udev,
    > + int timeout);

    Again, units please.

    > /* prepares the hardware to send commands to the device */
    > int (*enable_device)(struct usb_hcd *, struct usb_device *udev);
    > /* Notifies the HCD after a hub descriptor is fetched.
    > diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
    > index eeb7c2157c72..0cb464e3eaf4 100644
    > --- a/include/linux/usb/quirks.h
    > +++ b/include/linux/usb/quirks.h
    > @@ -72,4 +72,7 @@
    > /* device has endpoints that should be ignored */
    > #define USB_QUIRK_ENDPOINT_IGNORE BIT(15)
    >
    > +/* short device address timeout */
    > +#define USB_QUIRK_SHORT_DEVICE_ADDR_TIMEOUT BIT(16)

    Don't you also need to have a Documentation/ update for the new
    user/kernel api you are adding?

    thanks,

    greg k-h

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