Hi Simon,

On Mon, Oct 27, 2014 at 2:08 AM, Simon Horman [off-list ref] wrote:

On Thu, Oct 23, 2014 at 01:31:14PM +0200, Geert Uytterhoeven wrote:

quoted

The D4 power domain contains the Coresight-ETM hardware block.
As long as the ARM debug/perf code doesn't use resource management with
runtime PM support, the D4 power domain must be kept powered to avoid a
crash during resume from s2ram (dbg_cpu_pm_notify() calls
reset_ctrl_regs() unconditionally, causing an undefined instruction
oops).

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Untested on real hardware, but a similar workaround is needed on r8a7740.

I have hardware in the form of a Mackerel board and I'm happy
to test this if it would help and you give me some guidance on how to do so.

That would be great!

Test procedure:
  1. echo 0 > /sys/module/printk/parameters/console_suspend
  2. echo mem > /sys/power/state
  3. [ Wake up by pressing a key on the serial console.
        There's no other wake-up source on mackerel? ]

Without my patch, I expect it to crash during resume in reset_ctrl_regs().

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds