linux-kernel - Re: [PATCH v6] usb: Reduce the 'SET_ADDRESS' request timeout with a new quirk

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Date:   Thu, 26 Oct 2023 16:08:09 +0300
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Hardik Gajjar <hgajjar@...adit-jv.com>, gregkh@...uxfoundation.org,
        stern@...land.harvard.edu, mathias.nyman@...el.com
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        erosca@...adit-jv.com
Subject: Re: [PATCH v6] usb: Reduce the 'SET_ADDRESS' request timeout with a
 new quirk

On 26.10.2023 13.15, Hardik Gajjar wrote:
> This patch introduces a new USB quirk,
> USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT, which modifies the timeout value
> for the 'SET_ADDRESS' request. The standard timeout for USB request/command
> is 5000 ms, as recommended in the USB 3.2 specification (section 9.2.6.1).
> 
> However, certain scenarios, such as connecting devices through an APTIV
> hub, can lead to timeout errors when the device enumerates as full speed
> initially and later switches to high speed during chirp negotiation.
> 
> In such cases, USB analyzer logs reveal that the bus suspends for
> 5 seconds due to incorrect chirp parsing and resumes only after two
> consecutive timeout errors trigger a hub driver reset.
> 
> Packet(54) Dir(?) Full Speed J(997.100 us) Idle(  2.850 us)
> _______| Time Stamp(28 . 105 910 682)
> _______|_____________________________________________________________Ch0
> Packet(55) Dir(?) Full Speed J(997.118 us) Idle(  2.850 us)
> _______| Time Stamp(28 . 106 910 632)
> _______|_____________________________________________________________Ch0
> Packet(56) Dir(?) Full Speed J(399.650 us) Idle(222.582 us)
> _______| Time Stamp(28 . 107 910 600)
> _______|_____________________________________________________________Ch0
> Packet(57) Dir Chirp J( 23.955 ms) Idle(115.169 ms)
> _______| Time Stamp(28 . 108 532 832)
> _______|_____________________________________________________________Ch0
> Packet(58) Dir(?) Full Speed J (Suspend)( 5.347 sec) Idle(  5.366 us)
> _______| Time Stamp(28 . 247 657 600)
> _______|_____________________________________________________________Ch0
> 
> This 5-second delay in device enumeration is undesirable, particularly
> in automotive applications where quick enumeration is crucial
> (ideally within 3 seconds).
> 
> The newly introduced quirks provide the flexibility to align with a
> 3-second time limit, as required in specific contexts like automotive
> applications.
> 
> By reducing the 'SET_ADDRESS' request timeout to 500 ms, the
> system can respond more swiftly to errors, initiate rapid recovery, and
> ensure efficient device enumeration. This change is vital for scenarios
> where rapid smartphone enumeration and screen projection are essential.
> 
> 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/parameters/quirks"
> 
> Signed-off-by: Hardik Gajjar <hgajjar@...adit-jv.com>
> ---

For the xhci parts:

Reviewed-by: Mathias Nyman <mathias.nyman@...ux.intel.com>