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[Qemu-trivial] [PATCH] ohci: set effectively usb frame rate to 1kHz
From: |
Miguel GAIO |
Subject: |
[Qemu-trivial] [PATCH] ohci: set effectively usb frame rate to 1kHz |
Date: |
Thu, 27 Sep 2018 17:19:36 +0200 |
USB frame rate is slightly lower than 1kHz: ie. ~950Hz.
Thus usb-audio device is not able to perform a simple audio playback
without underruns on audio backend.
eg. "-device pci-ohci,id=ohci -device usb-audio,bus=ohci.0" vs PulseAudio
backend. more than 50 underruns are observed per second.
Update ohci_sof_time computation, using QEMU_CLOCK_VIRTUAL in
ohci_usb_start(), and increment by usb_frame_time in ohci_sof()
makes USB frame rate close to 1kHz.
This way, no audio underrun are observed during audio playback.
Signed-off-by: Miguel GAIO <address@hidden>
---
hw/usb/hcd-ohci.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index 98da5f0f04..66656a1133 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -1253,12 +1253,12 @@ static int ohci_service_ed_list(OHCIState *ohci,
uint32_t head, int completion)
/* set a timer for EOF */
static void ohci_eof_timer(OHCIState *ohci)
{
- ohci->sof_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
timer_mod(ohci->eof_timer, ohci->sof_time + usb_frame_time);
}
/* Set a timer for EOF and generate a SOF event */
static void ohci_sof(OHCIState *ohci)
{
+ ohci->sof_time += usb_frame_time;
ohci_eof_timer(ohci);
ohci_set_interrupt(ohci, OHCI_INTR_SF);
}
@@ -1362,6 +1362,7 @@ static int ohci_bus_start(OHCIState *ohci)
* can meet some race conditions
*/
+ ohci->sof_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
ohci_eof_timer(ohci);
return 1;
@@ -1476,6 +1477,9 @@ static uint32_t ohci_get_frame_remaining(OHCIState *ohci)
* set already.
*/
tks = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ohci->sof_time;
+ if (tks < 0) {
+ tks = 0;
+ }
/* avoid muldiv if possible */
if (tks >= usb_frame_time)
--
2.19.0
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