I've been doing some work on USB and ended up realizing that
gBS->Stall(1) is taking much longer than it should: on my Juno R2 it's
stalling for 100 us, while on my Raspberry Pi 4 it's 10 us.
This appears to be causing a USB bulk transfer request that asks for a
1ms timeout taking 100ms on the Juno.
I'm measuring the delay with the following code:
UINT64 First = GetPerformanceCounter ();
gBS->Stall (XHC_1_MICROSECOND);
UINT64 Second = GetPerformanceCounter ();
UINT64 FirstNs = GetTimeInNanoSecond (First);
UINT64 SecondNs = GetTimeInNanoSecond (Second);
DEBUG ((DEBUG_INFO, "Stalled for %llu ns (%llu ms)\n", (SecondNs -
FirstNs), (SecondNs - FirstNs) / 1024 / 1024));
I see output such as:
Stalled for 10500 ns (0 ms)
--
Rebecca Cran
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