[Skiboot] [PATCH v2 5/8] capp/phb4: Force CAPP to PCIe mode during kernel shutdown

[Andrew Donnellan]

On 10/12/18 1:17 am, Vaibhav Jain wrote:
> This patch introduces a new opal syncer for PHB4 named
> phb4_host_sync_reset(). We register this opal syncer when CAPP is
> activated successfully in phb4_set_capi_mode() so that it will be
> called at kernel shutdown during fast-reset.
> 
> During kernel shutdown the function will then repeatedly call
> phb->ops->set_capi_mode() to switch switch CAPP to PCIe mode. In case
> set_capi_mode() indicates its OPAL_BUSY, which indicates that CAPP is
> still transitioning to new state; it calls slot->ops.run_sm() to
> ensure that Opal slot reset state machine makes forward progress.
> 
> Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
> ---
>   hw/phb4.c | 39 +++++++++++++++++++++++++++++++++++++--
>   1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index df483e27..97c77a89 100644
> --- a/hw/phb4.c
> +++ b/hw/phb4.c
> @@ -2768,6 +2768,37 @@ static void phb4_training_trace(struct phb4 *p)
>   	}
>   }
>   
> +/*
> + * This helper is called repeatedly by the host sync notifier mechanism, which
> + * relies on the kernel to regularly poll the OPAL_SYNC_HOST_REBOOT call as it
> + * shuts down.
> + */
> +static bool phb4_host_sync_reset(void *data)
> +{
> +	struct phb4 *p = (struct phb4 *)data;
> +	struct phb *phb = &p->phb;
> +	int64_t rc = 0;
> +
> +	/* Make sure no-one modifies the phb flags while we are active */
> +	phb_lock(phb);
> +
> +	/* Make sure CAPP is attached to the PHB */
> +	if (phb->capp)
> +		/* Call phb ops to disable capi */
> +		rc = phb->ops->set_capi_mode(phb, OPAL_PHB_CAPI_MODE_PCIE,
> +				       phb->capp->attached_pe);
> +	else
> +		rc = OPAL_SUCCESS;

This code is fine, but I'm assuming that set_capi_mode() will still 
return OPAL_SUCCESS if the CAPP isn't attached, right?

...

>   static int64_t phb4_poll_link(struct pci_slot *slot)
>   {
>   	struct phb4 *p = phb_to_phb4(slot->phb);
> @@ -4419,7 +4450,7 @@ static int64_t phb4_init_capp(struct phb4 *p)
>   		capp->capp_xscom_offset = CAPP1_REG_OFFSET;
>   	}
>   
> -	capp->attached_pe = phb4_get_reserved_pe_number(phb);
> +	capp->attached_pe = phb4_get_reserved_pe_number(&p->phb);
>   
>   	/* Load capp microcode into the capp unit */
>   	load_capp_ucode(p);
> @@ -4462,7 +4493,8 @@ static int64_t phb4_set_capi_mode(struct phb *phb, uint64_t mode,
>   			break;
>   		}
>   
> -		xscom_read(p->chip_id, CAPP_ERR_STATUS_CTRL + offset, &reg);
> +		xscom_read(p->chip_id, CAPP_ERR_STATUS_CTRL +
> +			   capp->capp_xscom_offset, &reg);

These two hunks need to be moved to previous patches - snowpatch is 
reporting this breaks bisection.

With that fixed:

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

>   		if ((reg & PPC_BIT(5))) {
>   			PHBERR(p, "CAPP: recovery failed (%016llx)\n", reg);
>   			ret = OPAL_HARDWARE;
> @@ -4492,6 +4524,9 @@ static int64_t phb4_set_capi_mode(struct phb *phb, uint64_t mode,
>   					       CAPP_MAX_STQ_ENGINES |
>   					       CAPP_MIN_DMA_READ_ENGINES);
>   		if (ret == OPAL_SUCCESS) {
> +			/* register notification on system shutdown */
> +			opal_add_host_sync_notifier(&phb4_host_sync_reset, p);
> +
>   			/* Disable fast reboot for CAPP */
>   			disable_fast_reboot("CAPP being enabled");
>   		} else {
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited