According to the most up to date version of the dwc2 databook, the FRINT field of the HFIR register should be programmed to: * 125 us * (PHY clock freq for HS) - 1 * 1000 us * (PHY clock freq for FS/LS) - 1 This is opposed to older versions of the doc that claimed it should be: * 125 us * (PHY clock freq for HS) * 1000 us * (PHY clock freq for FS/LS) In case you didn't spot it, the difference is the "- 1". Let's add the "- 1" to match the newest user manual. It's presumed that the "- 1" should have always been there and that this was always a documentation error. If some hardware needs the "- 1" and other hardware doesn't, we'll have to add a configuration parameter for it in the future. I checked things before and after this patch on rk3288 using a Total Phase Beagle 5000 analyzer. Before this patch, a low speed mouse shows constant Frame Timing Jitter errors. After this patch errors have gone away. Before this patch SOF packets move forward about 1 us per 4 ms. After this patch the SOF packets move backward about 1 us per 255 ms. Some specific SOF timestamps from the analyzer are below. Before: 6.603.790 6.603.916 6.604.041 6.604.166 ... 6.607.541 6.607.667 6.607.792 6.607.917 ... 6.611.417 6.611.543 6.611.668 6.611.793 After: 6.215.159 6.215.284 6.215.408 6.215.533 6.215.658 ... 6.470.658 6.470.783 6.470.907 ... 6.726.032 6.726.157 6.725.281 6.725.406 Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> --- drivers/usb/dwc2/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c index 39a0fa8a4c0a..c7798476e25b 100644 --- a/drivers/usb/dwc2/core.c +++ b/drivers/usb/dwc2/core.c @@ -2251,10 +2251,10 @@ u32 dwc2_calc_frame_interval(struct dwc2_hsotg *hsotg) if ((hprt0 & HPRT0_SPD_MASK) >> HPRT0_SPD_SHIFT == HPRT0_SPD_HIGH_SPEED) /* High speed case */ - return 125 * clock; + return 125 * clock - 1; else /* FS/LS case */ - return 1000 * clock; + return 1000 * clock - 1; } /** -- 2.7.0.rc3.207.g0ac5344 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
