[Skiboot] [PATCH] init: Perform pstates-init before dt blob creation

[Vasant Hegde]

On 07/10/2019 05:59 PM, Gautham R. Shenoy wrote:
> From: "Gautham R. Shenoy" <ego at linux.vnet.ibm.com>
> 
> On FSP based systems (particularly POWER8), we perform
> occ_pstates_init() late in the boot to allow OCC to be loaded. Hence
> this was being performed in platform.exit(). occ_pstates_init() would
> add pstate information into the device-tree.
> 
> A recent commit 9fc0c1287ada ("Move FSP specific op-panel calls to
> platform.exit()") moved the invocation of platform.exit() after the
> creation of device-tree blob. As a result, on FSP based systems, we
> don't have the pstate information in the device-tree, and thus the
> Kernel is unable to perform frequency scaling.
> 
> Fix this by moving occ_pstates_init() out of ibm_fsp_exit() and call
> it before the creation of the device-tree blob.
> 
> Fixes: commit 9fc0c1287ada ("Move FSP specific op-panel calls to
> platform.exit()")
> 
> Signed-off-by: Gautham R. Shenoy <ego at linux.vnet.ibm.com>

Thanks for the fix.

> ---
>   core/init.c                | 6 ++++++
>   platforms/ibm-fsp/common.c | 7 -------
>   2 files changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/core/init.c b/core/init.c
> index d0f28f2..8eb0729 100644
> --- a/core/init.c
> +++ b/core/init.c
> @@ -557,6 +557,12 @@ void __noreturn load_and_boot_kernel(bool is_reboot)
>   		if (!occ_sensors_init())
>   			dts_sensor_create_nodes(sensor_node);
> 
> +		/*
> +		 * OCC takes few secs to boot on FSP systems. Call
> +		 * this as late as as possible to avoid delay.
> +		 */
> +		if (!platform.bmc)
> +			occ_pstates_init();

So you will end up calling occ_pstates_init() on simulators as well. Do you 
really want that?
Today its occ_pstates, tomorrow we may have something else.
IMO we should continue to have all those things inside platform.exit() function 
and move
platform.exit function just before creating dtb.


>   	} else {
>   		/* fdt will be rebuilt */
>   		free(fdt);
> diff --git a/platforms/ibm-fsp/common.c b/platforms/ibm-fsp/common.c
> index 7f7a1f2..6da25d1 100644
> --- a/platforms/ibm-fsp/common.c
> +++ b/platforms/ibm-fsp/common.c
> @@ -186,13 +186,6 @@ void ibm_fsp_exit(void)
>   	/* Wait for FW VPD data read to complete */
>   	fsp_code_update_wait_vpd(true);
> 
> -	/*
> -	 * OCC takes few secs to boot.  Call this as late as
> -	 * as possible to avoid delay.
> -	 */
> -	if (fsp_present())
> -		occ_pstates_init();

Given that its inside fsp exit() function, fsp_present() check is redundant. We 
should cleanup that.

-Vasant