| From | Geert Uytterhoeven <> | Date | Sun, 12 Apr 2020 10:44:01 +0200 | Subject | Re: [PATCH AUTOSEL 5.4 095/108] ARM: shmobile: Enable ARM_GLOBAL_TIMER on Cortex-A9 MPCore SoCs |
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Hi Sasha,
On Sun, Apr 12, 2020 at 1:11 AM Sasha Levin <sashal@kernel.org> wrote: > From: Geert Uytterhoeven <geert+renesas@glider.be> > > [ Upstream commit 408324a3c5383716939eea8096a0f999a0665f7e ] > > SH-Mobile AG5 and R-Car H1 SoCs are based on the Cortex-A9 MPCore, which > includes a global timer. > > Enable the ARM global timer on these SoCs, which will be used for: > - the scheduler clock, improving scheduler accuracy from 10 ms to 3 or > 4 ns, > - delay loops, allowing removal of calls to shmobile_init_delay() from > the corresponding machine vectors. > > Note that when using an old DTB lacking the global timer, the kernel > will still work. However, loops-per-jiffies will no longer be preset, > and the delay loop will need to be calibrated during boot.
I.e. to avoid this delay, this patch is best backported after backporting 8443ffd1bbd5be74 ("ARM: dts: r8a7779: Add device node for ARM global timer"), df1a0aac0a533e6f ("ARM: dts: sh73a0: Add device node for ARM global timer").
While the former has been backported to v5.[45]-stable, the latter hasn't, probably because it depends on 61b58e3f6e518c51 ("ARM: dts: sh73a0: Rename twd clock to periph clock")
So please backport the last two commits first. Thanks!
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > Link: https://lore.kernel.org/r/20191211135222.26770-5-geert+renesas@glider.be > Signed-off-by: Sasha Levin <sashal@kernel.org>
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@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
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