Hi Geert,
On Wed, Jan 22, 2020 at 08:31:44AM +0100, Geert Uytterhoeven wrote:
> On Wed, Jan 22, 2020 at 3:34 AM Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> wrote:
> >
> > So, what's specific to R-Car3, based on my testing, is that the issue
> > can only be reproduced if the printk storm originates on CPU0 (it does
> > not matter if from interrupt or task context, both have been tested). If
> > the printk storm is initiated on any other CPU (there are 7 secondary
> > ones on R-Car H3), there is no regression in the audio quality/latency.
>
> The secure stuff is running on CPU0, isn't it?
> Is that a coincidence?
Nobody has ruled this out so far. As a side note, except for the ARMv8
generic IPs, there seems to be quite poor IRQ balancing between the
CPU cores of R-Car H3 (although this might be unrelated to the issue):
$ cat /proc/interrupts | egrep -v "(0[ ]*){8}"
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
3: 55879 17835 14132 33882 6626 4331 6710 4532 GICv2 30 Level arch_timer
16: 1 0 0 0 0 0 0 0 GICv2 38 Level e6052000.gpio
32: 203 0 0 0 0 0 0 0 GICv2 51 Level e66d8000.i2c
33: 95 0 0 0 0 0 0 0 GICv2 205 Level e60b0000.i2c
94: 19339 0 0 0 0 0 0 0 GICv2 71 Level eth0:ch0:rx_be
112: 20599 0 0 0 0 0 0 0 GICv2 89 Level eth0:ch18:tx_be
118: 2 0 0 0 0 0 0 0 GICv2 95 Level eth0:ch24:emac
122: 442092 0 0 0 0 0 0 0 GICv2 196 Level e6e88000.serial:mux
124: 2776685 0 0 0 0 0 0 0 GICv2 352 Level ec700000.dma-controller:0
160: 2896 0 0 0 0 0 0 0 GICv2 197 Level ee100000.sd
161: 5652 0 0 0 0 0 0 0 GICv2 199 Level ee140000.sd
162: 147 0 0 0 0 0 0 0 GICv2 200 Level ee160000.sd
197: 5 0 0 0 0 0 0 0 GICv2 384 Level ec500000.sound
208: 1 0 0 0 0 0 0 0 gpio-rcar 11 Level e6800000.ethernet-ffffffff:00
IPI0: 12701 366358 545059 1869017 9817 8065 9327 10644 Rescheduling interrupts
IPI1: 21 34 111 86 238 191 149 161 Function call interrupts
IPI5: 16422 709 509 637 0 0 3346 0 IRQ work interrupts
BTW/FYI, I raised a bug report to Renesas and specifically asked them
to approach you, hoping that your massive experience in the serial
drivers will help. If you arrive to any conclusions in that context,
we would be delighted to hear from you.
--
Best Regards
Eugeniu Rosca
