linux-kernel - Re: [linux-sunxi] [PATCH] ARM: sunxi: Fix CPU powerdown on A83T

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Message-ID: <20191029012517.eddekmphtxyslevx@core.my.home>
Date:   Tue, 29 Oct 2019 02:25:17 +0100
From:   Ondřej Jirman <megous@...ous.com>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     linux-sunxi <linux-sunxi@...glegroups.com>,
        stable <stable@...r.kernel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        "moderated list:ARM/Allwinner sunXi SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [linux-sunxi] [PATCH] ARM: sunxi: Fix CPU powerdown on A83T

On Tue, Oct 29, 2019 at 09:09:40AM +0800, Chen-Yu Tsai wrote:
> On Tue, Oct 29, 2019 at 5:49 AM Ondrej Jirman <megous@...ous.com> wrote:
> >
> > PRCM_PWROFF_GATING_REG has CPU0 at bit 4 on A83T. So without this
> > patch, instead of gating the CPU0, the whole cluster was power gated,
> > when shutting down first CPU in the cluster.
> >
> > Fixes: 6961275e72a8c1 ("ARM: sun8i: smp: Add support for A83T")
> > Signed-off-by: Ondrej Jirman <megous@...ous.com>
> > Cc: stable@...r.kernel.org
> 
> Acked-by: Chen-Yu Tsai <wens@...e.org>
> 
> Though I distinctly remember the BSP had some code dealing with chip
> revisions in which the two bits were reversed. :(

Actually, it's a bit more complicated. There's a special check in BSP
code (grep for SUN8IW6P1_REV_A) that instead of power gating, just
holds the core in reset for that revision.

regards,
	o.