linux-kernel - Re: [PATCH v2 1/3] ARC: mcip: halt GFRC together with ARC cores

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Date:   Fri, 23 Feb 2018 17:38:04 -0800
From:   Vineet Gupta <Vineet.Gupta1@...opsys.com>
To:     Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Alexey Brodkin" <Alexey.Brodkin@...opsys.com>
Subject: Re: [PATCH v2 1/3] ARC: mcip: halt GFRC together with ARC cores

On 02/23/2018 08:41 AM, Eugeniy Paltsev wrote:
> Currently GFRC is running regardless state of ARC cores in the SMP cluster.
> That means even if ARC cores are halted when doing JTAG debugging GFRC
> [our source of wall-time] continues to run giving us unexpected warnings
> once we allow ARC cores to run due to some tasks being stuck for too
> long.
>
> Starting from ARC HS v3.0 it's possible to tie GFRC to state of up-to 4
> ARC cores with help of GFRC's CORE register where we set a mask for
> cores which state we need to rely on.
>
> We update cpu mask every time new cpu came online instead of using
> hardcoded one or using mask generated from "possible_cpus" as we
> want it set correctly even if we run kernel on HW which has fewer cores
> than expected (or we launch kernel via debugger and kick fever cores
> than HW has)
>
> Signed-off-by: Alexey Brodkin<abrodkin@...opsys.com>
> Signed-off-by: Eugeniy Paltsev<Eugeniy.Paltsev@...opsys.com>

Acked-by: vineet Gupta <vgupta@...opsys.com>