[Skiboot] [PATCH] slw: use only lite stop states for P9 DD1

[Michael Neuling]

On Fri, 2017-02-17 at 23:07 +0530, Vaidyanathan Srinivasan wrote:
> From: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
> 
> POWER9 DD1 chip can work with lite stop states now. These
> STOP states have ESL=EC=0 and provide fast entry/exit.
> 
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
> Signed-off-by: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
> ---
>  hw/slw.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/hw/slw.c b/hw/slw.c
> index 81e4e4a..2415019 100644
> --- a/hw/slw.c
> +++ b/hw/slw.c
> @@ -649,6 +649,8 @@ void add_cpu_idle_state_properties(void)
>  	u32 *residency_ns_buf;
>  	u32 *flags_buf;
>  
> +	bool only_lite = false;
> +
>  	prlog(PR_DEBUG, "CPU idle state device tree init\n");
>  
>  	/* Create /ibm,opal/power-mgt if it doesn't exist already */
> @@ -683,6 +685,9 @@ void add_cpu_idle_state_properties(void)
>  		if (!stop_levels)
>  			prerror("SLW: No stop levels available. Power saving
> is disabled!\n");
>  
> +		/* Force only lite states for DD1.0 */
> +		if (chip->ec_level == 0x10)
> +			only_lite = true;
>  	} else if (chip->type == PROC_CHIP_P8_MURANO ||
>  	    chip->type == PROC_CHIP_P8_VENICE ||
>  	    chip->type == PROC_CHIP_P8_NAPLES) {
> @@ -757,10 +762,15 @@ void add_cpu_idle_state_properties(void)
>  			supported_states_mask |= OPAL_PM_WINKLE_ENABLED;
>  	}
>  	for (i = 0; i < nr_states; i++) {
> +		u64 esl = states[i].pm_ctrl_reg_val & OPAL_PM_PSSCR_ESL;
> +
>  		/* For each state, check if it is one of the supported
> states. */
>  		if (!(states[i].flags & supported_states_mask))
>  			continue;
>  
> +		if (only_lite && esl)
> +			continue;
> +

Can we just check the ec_level here and eliminate the only_lite variable?

Mikey

>  		/* We can only use the stop levels that HB has made available
> */
>  		if (has_stop_inst) {
>  			u32 level = 31 - (states[i].pm_ctrl_reg_val &
> @@ -770,6 +780,8 @@ void add_cpu_idle_state_properties(void)
>  				continue;
>  		}
>  
> +		prlog(PR_NOTICE, "SLW: Enabling: %s\n", states[i].name);
> +
>  		/*
>  		 * If a state is supported add each of its property
>  		 * to its corresponding property buffer.