[Skiboot] [PATCH skiboot] hw/phb3/naples: Disable D-states

[David Gibson]

On Fri, Jan 11, 2019 at 03:06:52PM +1100, Alexey Kardashevskiy wrote:
> Putting "Mellanox Technologies MT27700 Family [ConnectX-4] [15b3:1013]"
> (more precisely, the second of 2 its PCI functions, no matter in what
> order) into the D3 state causes EEH with the "PCT timeout" error.
> This has been noticed on garrison machines only and firestones do not
> seem to have this issue.
> 
> This disables D-states changing for devices on root buses on Naples by
> installing a config space access filter (copied from PHB4).
> 
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

Um.. what case is this trying to affect?  hw/phb3.c is only used with
pnv machines which are unlikely to be using passed through devices.

> ---
>  hw/phb3.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/hw/phb3.c b/hw/phb3.c
> index 771ccfc..04c8b78 100644
> --- a/hw/phb3.c
> +++ b/hw/phb3.c
> @@ -573,6 +573,22 @@ static void phb3_endpoint_init(struct phb *phb,
>  	pci_cfg_write32(phb, bdfn, aercap + PCIECAP_AER_CAPCTL, val32);
>  }
>  
> +static int64_t phb3_pcicfg_no_dstate(void *dev __unused,
> +				     struct pci_cfg_reg_filter *pcrf,
> +				     uint32_t offset, uint32_t len __unused,
> +				     uint32_t *data __unused,  bool write)
> +{
> +	uint32_t loff = offset - pcrf->start;
> +
> +	/* Disable D-state change on children of the PHB. For now we
> +	 * simply block all writes to the PM control/status
> +	 */
> +	if (write && loff >= 4 && loff < 6)
> +		return OPAL_SUCCESS;
> +
> +	return OPAL_PARTIAL;
> +}
> +
>  static void phb3_check_device_quirks(struct phb *phb, struct pci_device *dev)
>  {
>  	struct phb3 *p = phb_to_phb3(phb);
> @@ -601,6 +617,19 @@ static void phb3_check_device_quirks(struct phb *phb, struct pci_device *dev)
>  		else
>  			modectl &= ~PPC_BIT(14);
>  		xscom_write(p->chip_id, p->pe_xscom + 0x0b, modectl);
> +
> +		/*
> +		 * Naples has a problem with D-states at least on Mellanox CX4,
> +		 * disable changing D-state on Naples like we do it for PHB4.
> +		 */
> +		if (PHB3_IS_NAPLES(p) &&
> +		    pci_has_cap(dev, PCI_CFG_CAP_ID_PM, false)) {
> +			pci_add_cfg_reg_filter(dev,
> +					pci_cap(dev, PCI_CFG_CAP_ID_PM, false),
> +					8,
> +					PCI_REG_FLAG_WRITE,
> +					phb3_pcicfg_no_dstate);
> +		}
>  	} else if (dev->primary_bus == 0) {
>  		/*
>  		 * Emulate the prefetchable window of the root port

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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