linux-kernel - Re: [PATCH v3 1/3] powernv:idle: Add IDLE_STATE_ENTER_SEQ

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Date:   Tue, 29 Nov 2016 21:42:20 +1100
From:   Balbir Singh <bsingharora@...il.com>
To:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michael Neuling <mikey@...ling.org>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>
Cc:     "\"linuxppc-dev"@lists.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, "skiboot\""@lists.ozlabs.org
Subject: Re: [PATCH v3 1/3] powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro



On 10/11/16 18:54, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>
> 
> Currently all the low-power idle states are expected to wake up
> at reset vector 0x100. Which is why the macro IDLE_STATE_ENTER_SEQ
> that puts the CPU to an idle state and never returns.
> 
> On ISA_300, when the ESL and EC bits in the PSSCR are zero, the
> CPU is expected to wake up at the next instruction of the idle
> instruction.
> 
> This patch adds a new macro named IDLE_STATE_ENTER_SEQ_NORET for the

I think something like IDLE_STATE_ENTER_SEQ_LOSE_CTX would be better?

> no-return variant and reuses the name IDLE_STATE_ENTER_SEQ
> for a variant that allows resuming operation at the instruction next
> to the idle-instruction.
> 
<snip>
> +
> +#define	IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST)			\
> +	IDLE_STATE_ENTER_SEQ(IDLE_INST)                         \

So we start off with both as the same?

>  	b	.
>  #endif /* CONFIG_PPC_P7_NAP */
<snip>
Balbir