On 11.6.2024 17.45, joswang wrote:
On Tue, Jun 11, 2024 at 6:01 PM Mathias Nyman
<mathias.nyman@xxxxxxxxxxxxxxx> wrote:
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
As you mentioned，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...
xhci_handle_events()
......
if (event_loop++ > TRBS_PER_SEGMENT / 2) {
if (ir->isoc_bei_interval > AVOID_BEI_INTERVAL_MIN)
ir->isoc_bei_interval = ir->isoc_bei_interval / 2;
}
.......
Yes, and to me this seems reasonable .
If there are over 128 events per interrupt then we should interrupt more often.
Would this work as the default for the Synopsys hosts you are working with?
Thanks
Mathias
