Re: [PATCH] arm64: dts: imx8mp: add cpuidle state "cpu-pd-wait"

Laurent Pinchart
2025-04-15T15:47:27Z

Hi Catalin,

On Tue, Apr 15, 2025 at 03:42:22PM +0000, POPESCU Catalin wrote:
> Hi Jai,
>
> This issue was already reported by Stefan. The problem is that I don't
> have a Debix board to investigate.
> The main difference b/w WFI and cpu-pd-wait is that the first doesn't
> call PSCI/TF-A. So, the issue looks to be related to some settings in
> the TF-A.

Jai, are you using mainline U-Boot and TF-A, or a downstream version of
either (or both) ?

> What I don't get is why I don't see this issue neither on our IMX8MP
> specific design nor on the EVK, which uses the same PHY as the Debix board.
>
> On 14/04/2025 14:07, Jai Luthra wrote:
> > On Oct 21, 2024 at 17:42:34 +0800, Shawn Guo wrote:
> >> On Mon, Oct 07, 2024 at 03:44:24PM +0200, Catalin Popescu wrote:
> >>> So far, only WFI is supported on i.MX8mp platform. Add support for
> >>> deeper cpuidle state "cpu-pd-wait" that would allow for better power
> >>> usage during runtime. This is a port from NXP downstream kernel.
> >>>
> > Since the introduction of this patch in mainline, I am facing sluggish
> > network performance with my Debix Model-A board with i.MX8mp SoC.
> >
> > The network latency jumps to >1s after almost every other packet:
> >
> > PING debix (10.0.42.5) 56(84) bytes of data.
> > 64 bytes from debix (10.0.42.5): icmp_seq=1 ttl=64 time=1008 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=2 ttl=64 time=0.488 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=3 ttl=64 time=1025 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=4 ttl=64 time=0.810 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=5 ttl=64 time=590 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=6 ttl=64 time=0.351 ms
> > ^C
> > --- debix ping statistics ---
> > 7 packets transmitted, 6 received, 14.2857% packet loss, time 6126ms
> > rtt min/avg/max/mdev = 0.351/437.416/1024.755/459.370 ms, pipe 2
> > darkapex at freya in ~
> >
> > If I revert the patch, or disable the deeper cpuidle state through
> > sysfs, the issue goes away.
> >
> > # echo 1 > /sys/devices/system/cpu/cpu$i/cpuidle/state1/disable
> >
> > PING debix (10.0.42.5) 56(84) bytes of data.
> > 64 bytes from debix (10.0.42.5): icmp_seq=1 ttl=64 time=0.482 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=2 ttl=64 time=2.28 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=3 ttl=64 time=2.26 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=4 ttl=64 time=0.848 ms
> > 64 bytes from debix (10.0.42.5): icmp_seq=5 ttl=64 time=0.406 ms
> > ^C
> > --- debix ping statistics ---
> > 5 packets transmitted, 5 received, 0% packet loss, time 4051ms
> > rtt min/avg/max/mdev = 0.406/1.255/2.280/0.842 ms
> >
> >>> Signed-off-by: Catalin Popescu <catalin.popescu@leica-geosystems.com>
> >>
> >> Applied, thanks!

--
Regards,

Laurent Pinchart