Subject: [PATCH - v4] PCI: keystone: add a pci quirk to limit mrrs

From: [email-masked] (Murali Karicheri)
Date: Thu, 11 Sep 2014 15:07:30 -0400

On 09/08/2014 01:03 PM, Murali Karicheri wrote:
> Keystone PCI controller has a limitation that memory read request
> size must not exceed 256 bytes. This is a hardware limitation and
> add a quirk to force this limit on all downstream devices by
> updating mrrs.
>
> Signed-off-by: Murali Karicheri<[email-masked]>
> ---
>    -v4: re-send removing extra lines
>    -v3: added check for vendor id and use pci_matc_id() to do matching
>    -v2: made the quirk happens after tuning
>    -v1: changed printk to indicate PCI bdf
>
>   drivers/pci/host/pci-keystone.c |   45 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 45 insertions(+)
>
> diff --git a/drivers/pci/host/pci-keystone.c b/drivers/pci/host/pci-keystone.c
> index c1cfaef..ff8ed25 100644
> --- a/drivers/pci/host/pci-keystone.c
> +++ b/drivers/pci/host/pci-keystone.c
> @@ -42,8 +42,53 @@
>   /* DEV_STAT_CTRL */
>   #define PCIE_CAP_BASE		0x70
>
> +/* PCIE controller device IDs */
> +#define PCIE_RC_K2HK		0xb008
> +#define PCIE_RC_K2E		0xb009
> +#define PCIE_RC_K2L		0xb00a
> +
>   #define to_keystone_pcie(x)	container_of(x, struct keystone_pcie, pp)
>
> +static void quirk_limit_mrrs(struct pci_dev *dev)
> +{
> +	struct pci_bus *bus = dev->bus;
> +	struct pci_dev *bridge = bus->self;
> +	static const struct pci_device_id rc_pci_devids[] = {
> +		{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2HK),
> +		 .class = PCI_CLASS_BRIDGE_PCI<<  8, .class_mask = ~0, },
> +		{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2E),
> +		 .class = PCI_CLASS_BRIDGE_PCI<<  8, .class_mask = ~0, },
> +		{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2L),
> +		 .class = PCI_CLASS_BRIDGE_PCI<<  8, .class_mask = ~0, },
> +		{ 0, },
> +	};
> +
> +	if (pci_is_root_bus(bus))
> +		return;
> +
> +	/* look for the host bridge */
> +	while (!pci_is_root_bus(bus)) {
> +		bridge = bus->self;
> +		bus = bus->parent;
> +	}
> +
> +	if (bridge) {
> +		/*
> +		 * Keystone PCI controller has a h/w limitation of
> +		 * 256 bytes maximum read request size. It can't handle
> +		 * anything higher than this. So force this limit on
> +		 * all downstream devices
> +		 */
> +		if (pci_match_id(rc_pci_devids, bridge)) {
> +			if (pcie_get_readrq(dev)>  256) {
> +				dev_info(&dev->dev, "limiting mrrs to 256\n");
> +				pcie_set_readrq(dev, 256);
> +			}
> +		}
> +	}
> +}
> +DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, quirk_limit_mrrs);
> +
>   static int ks_pcie_establish_link(struct keystone_pcie *ks_pcie)
>   {
>   	struct pcie_port *pp =&ks_pcie->pp;
Bjorn,

If this version looks good, could you please apply this to host-keystone?

Thanks

Murali