Re: [RFC 1/1] usb: host: xhci-plat: add enable XHCI-AVOID-BEI quirk by dts

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 6.6.2024 17.08, joswang wrote:
On Wed, Jun 5, 2024 at 6:31 PM Mathias Nyman
<mathias.nyman@xxxxxxxxxxxxxxx> wrote:
...

I was thinking of turning XHCI_AVOID_BEI behavior into the new default, so no
quirk flag would be needed:

Currently without the quirk flag:

- ISOC TRBs trigger interrupt if TRB is the last in the TD

Currently with XHCI_AVOID_BEI quirk flag:

- ISOC TRBs trigger interrupt if TRB is the last in the TD
- Interrupt is additionally triggered every 32 isoc TRB (initially).
- if more than 128 events are processed in one interrupt then the
    32 is halved, and we trigger an interrupts every 16th isoc TRB, and so
    on, 16 -> 8...

I would remove the quirk flag, and make all controllers interrupt
behave as if it was set. i.e. interrupt at least every 32 isoc TRB

Thank you for your detailed analysis.
Excuse me, I have a question, do you mean to set "Currently with
XHCI_AVOID_BEI quirk flag" as the default behavior?

Yes, unless it causes some issues or there are strong objections


Is there an actual real world case where interrupting every 32nd ISOC TRB is
too often?

I mean that if the XHCI_AVOID_BEI quirk flag is set, an interrupt will
be triggered every 8 TRBs, which makes the interrupts seem to be quite
frequent.
Thanks
Jos


It should start with interrupting every 32nd isoc TD, not 8th

#define AVOID_BEI_INTERVAL_MAX   32

ir->isoc_bei_interval = AVOID_BEI_INTERVAL_MAX;

Thanks
Mathias




[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux