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Message-ID: <2023100921-likeness-possible-032c@gregkh>
Date: Mon, 9 Oct 2023 19:43:09 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Hardik Gajjar <hgajjar@...adit-jv.com>
Cc: mathias.nyman@...el.com, stern@...land.harvard.edu,
yangyingliang@...wei.com, jinpu.wang@...os.com,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
erosca@...adit-jv.com
Subject: Re: [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@...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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