[Skiboot] [PATCH v3 5/8] capp/phb4: Force CAPP to PCIe mode during kernel shutdown

[Frederic Barrat]

Le 08/01/2019 à 10:58, Vaibhav Jain a écrit :
> 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>
> ---
> Change-log
> 
> v3:	Updated code to use struct phb4->capp instead of struct phb->capp.
> ---

The test of OPAL_BUSY to know when to run the state machine looked 
surprising at first, but makes sense after reading the later patches.

Reviewed-by: Frederic Barrat <fbarrat at linux.ibm.com>


>   hw/phb4.c | 34 ++++++++++++++++++++++++++++++++++
>   1 file changed, 34 insertions(+)
> 
> diff --git a/hw/phb4.c b/hw/phb4.c
> index eba9ae3f..229617c5 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 (p->capp)
> +		/* Call phb ops to disable capi */
> +		rc = phb->ops->set_capi_mode(phb, OPAL_PHB_CAPI_MODE_PCIE,
> +				       p->capp->attached_pe);
> +	else
> +		rc = OPAL_SUCCESS;
> +
> +	/* Continue kicking state-machine if in middle of a mode transition */
> +	if (rc == OPAL_BUSY)
> +		rc = phb->slot->ops.run_sm(phb->slot);
> +
> +	phb_unlock(phb);
> +
> +	return rc <= OPAL_SUCCESS;
> +}
> +
>   static int64_t phb4_poll_link(struct pci_slot *slot)
>   {
>   	struct phb4 *p = phb_to_phb4(slot->phb);
> @@ -4492,6 +4523,9 @@ 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 {
>