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Date: Fri, 25 May 2018 08:30:09 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Nicolas Boichat <drinkcat@...omium.org>
Cc: linux-usb@...r.kernel.org, Alan Stern <stern@...land.harvard.edu>,
Mathias Nyman <mathias.nyman@...ux.intel.com>,
Felipe Balbi <felipe.balbi@...ux.intel.com>,
Eugene Korenevsky <ekorenevsky@...il.com>,
Peter Chen <peter.chen@....com>,
Daniel Drake <drake@...lessm.com>,
Joe Perches <joe@...ches.com>, Johan Hovold <johan@...nel.org>,
Richard Leitner <richard.leitner@...data.com>,
linux-kernel@...r.kernel.org, groeck@...omium.org
Subject: Re: [PATCH] usb: hub: Per-port setting to use old enumeration scheme
On Wed, May 23, 2018 at 10:16:56AM +0800, Nicolas Boichat wrote:
> The "old" enumeration scheme is considerably faster (it takes
> ~294ms instead of ~439ms to get the descriptor).
>
> It is currently only possible to use the old scheme globally
> (/sys/module/usbcore/parameters/old_scheme_first), which is not
> desirable as the new scheme was introduced to increase compatibility
> with more devices.
>
> However, in our case, we care about time-to-active for a specific
> USB device (which we make the firmware for), on a specific port
> (that is pogo-pin based: not a standard USB port). This new
> sysfs option makes it possible to use the old scheme on a single
> port only.
>
> Signed-off-by: Nicolas Boichat <drinkcat@...omium.org>
> ---
>
> There are other "quirks" that we could add to reduce further
> enumeration time (e.g. reduce USB debounce time, reduce TRSTRCY
> to 10ms instead of 50ms as used currently), but the logic is quite
> similar, so it'd be good to have this reviewed first.
>
> drivers/usb/core/hub.c | 13 +++++++++----
> drivers/usb/core/hub.h | 1 +
> drivers/usb/core/port.c | 23 +++++++++++++++++++++++
> include/linux/usb.h | 7 +++++++
> 4 files changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index c2d993d3816f0..f900f66a62856 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2636,7 +2636,7 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
> #define SET_ADDRESS_TRIES 2
> #define GET_DESCRIPTOR_TRIES 2
> #define SET_CONFIG_TRIES (2 * (use_both_schemes + 1))
> -#define USE_NEW_SCHEME(i) ((i) / 2 == (int)old_scheme_first)
> +#define USE_NEW_SCHEME(i, scheme) ((i) / 2 == (int)scheme)
>
> #define HUB_ROOT_RESET_TIME 60 /* times are in msec */
> #define HUB_SHORT_RESET_TIME 10
> @@ -2651,12 +2651,16 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
> * enumeration failures, so disable this enumeration scheme for USB3
> * devices.
> */
> -static bool use_new_scheme(struct usb_device *udev, int retry)
> +static bool use_new_scheme(struct usb_device *udev, int retry,
> + struct usb_port *port_dev)
> {
> + int old_scheme_first_port =
> + port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME;
> +
> if (udev->speed >= USB_SPEED_SUPER)
> return false;
>
> - return USE_NEW_SCHEME(retry);
> + return USE_NEW_SCHEME(retry, old_scheme_first_port || old_scheme_first);
> }
>
> /* Is a USB 3.0 port in the Inactive or Compliance Mode state?
> @@ -4392,6 +4396,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> {
> struct usb_device *hdev = hub->hdev;
> struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
> + struct usb_port *port_dev = hub->ports[port1 - 1];
> int retries, operations, retval, i;
> unsigned delay = HUB_SHORT_RESET_TIME;
> enum usb_device_speed oldspeed = udev->speed;
> @@ -4513,7 +4518,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
> bool did_new_scheme = false;
>
> - if (use_new_scheme(udev, retry_counter)) {
> + if (use_new_scheme(udev, retry_counter, port_dev)) {
> struct usb_device_descriptor *buf;
> int r = 0;
>
> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> index 4dc769ee9c740..4accfb63f7dcb 100644
> --- a/drivers/usb/core/hub.h
> +++ b/drivers/usb/core/hub.h
> @@ -98,6 +98,7 @@ struct usb_port {
> struct mutex status_lock;
> u32 over_current_count;
> u8 portnum;
> + u32 quirks;
> unsigned int is_superspeed:1;
> unsigned int usb3_lpm_u1_permit:1;
> unsigned int usb3_lpm_u2_permit:1;
> diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
> index 6979bde87d310..4a21431953953 100644
> --- a/drivers/usb/core/port.c
> +++ b/drivers/usb/core/port.c
> @@ -50,6 +50,28 @@ static ssize_t over_current_count_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(over_current_count);
>
> +static ssize_t quirks_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct usb_port *port_dev = to_usb_port(dev);
> +
> + return sprintf(buf, "%08x\n", port_dev->quirks);
> +}
> +
> +static ssize_t quirks_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct usb_port *port_dev = to_usb_port(dev);
> + u32 value;
> +
> + if (kstrtou32(buf, 16, &value))
> + return -EINVAL;
> +
> + port_dev->quirks = value;
> + return count;
> +}
> +static DEVICE_ATTR_RW(quirks);
> +
> static ssize_t usb3_lpm_permit_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> @@ -118,6 +140,7 @@ static DEVICE_ATTR_RW(usb3_lpm_permit);
>
> static struct attribute *port_dev_attrs[] = {
> &dev_attr_connect_type.attr,
> + &dev_attr_quirks.attr,
> &dev_attr_over_current_count.attr,
> NULL,
> };
Oops, you add a new sysfs file, but do not document it anywhere. It
needs to go into Documentation/ABI/ along with the other files,
otherwise no one knows how to use it.
Please fix that up and resend.
thanks,
greg k-h
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