On Mon, Oct 09, 2023 at 03:16:25PM -0400, Alan Stern wrote: > 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. > > What will you do about scenarios where the Set-Address completes very > quickly but the following Get-Device-Descriptor times out after 5 > seconds? Or any of the other transfers involved in device > initialization and enumeration? This issue occurs when the device first enumerates as full speed and then as a high-speed device. It appears that the set_address request is issued as soon as the device is detected as full speed. However, during the progress of the set_address request, the device changes its state from full speed to high speed, causing the set_address request to become stuck until it times out. Stress testing of USB devices indicates that the problem is specific to the set_address request. Other requests, such as device descriptor requests, consistently fail immediately with a protocol error in almost all cases. > > > 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. > > > > 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@xxxxxxxxxxxxxx> > > --- > > 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 */ > > That number, 125, is meaningless. It's in units of jiffies, which vary > from one system to another. If you want the timeout to be about 500 ms, > you should write it as (HZ / 2). Good Point, Thanks, I will update in patch v3 > > Alan Stern
