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SubjectRe: [PATCH v2 1/2] PCI: iproc: Add CRS check in config read
On Tue, Feb 05, 2019 at 10:27:00AM +0530, Srinath Mannam wrote:
> In the current implementation, config read output data 0xffff0001 is
> assumed as CRS completion. But sometimes 0xffff0001 can be a valid data.
>
> IPROC PCIe host controller has a register to show config read request
> status flags like SC, UR, CRS and CA. So that extra check is added to
> confirm the CRS using status flags before reissue config read.
>
> Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
> ---
> drivers/pci/controller/pcie-iproc.c | 23 +++++++++++++++++++++--
> 1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
> index c20fd6b..b882255 100644
> --- a/drivers/pci/controller/pcie-iproc.c
> +++ b/drivers/pci/controller/pcie-iproc.c
> @@ -60,6 +60,10 @@
> #define APB_ERR_EN_SHIFT 0
> #define APB_ERR_EN BIT(APB_ERR_EN_SHIFT)
>
> +#define CFG_RD_SUCCESS 0
> +#define CFG_RD_UR 1
> +#define CFG_RD_CRS 2
> +#define CFG_RD_CA 3
> #define CFG_RETRY_STATUS 0xffff0001
> #define CFG_RETRY_STATUS_TIMEOUT_US 500000 /* 500 milliseconds */
>
> @@ -289,6 +293,9 @@ enum iproc_pcie_reg {
> IPROC_PCIE_IARR4,
> IPROC_PCIE_IMAP4,
>
> + /* config read status */
> + IPROC_PCIE_CFG_RD_STATUS,
> +
> /* link status */
> IPROC_PCIE_LINK_STATUS,
>
> @@ -350,6 +357,7 @@ static const u16 iproc_pcie_reg_paxb_v2[] = {
> [IPROC_PCIE_IMAP3] = 0xe08,
> [IPROC_PCIE_IARR4] = 0xe68,
> [IPROC_PCIE_IMAP4] = 0xe70,
> + [IPROC_PCIE_CFG_RD_STATUS] = 0xee0,

So, with the *current* code, on controllers that does not support this
register you won't be able to get any HW whose config space register
value reads 0xffff0001 to work, is that correct ?

Lorenzo

> [IPROC_PCIE_LINK_STATUS] = 0xf0c,
> [IPROC_PCIE_APB_ERR_EN] = 0xf40,
> };
> @@ -474,10 +482,12 @@ static void __iomem *iproc_pcie_map_ep_cfg_reg(struct iproc_pcie *pcie,
> return (pcie->base + offset);
> }
>
> -static unsigned int iproc_pcie_cfg_retry(void __iomem *cfg_data_p)
> +static unsigned int iproc_pcie_cfg_retry(struct iproc_pcie *pcie,
> + void __iomem *cfg_data_p)
> {
> int timeout = CFG_RETRY_STATUS_TIMEOUT_US;
> unsigned int data;
> + u32 status;
>
> /*
> * As per PCIe spec r3.1, sec 2.3.2, CRS Software Visibility only
> @@ -498,6 +508,15 @@ static unsigned int iproc_pcie_cfg_retry(void __iomem *cfg_data_p)
> */
> data = readl(cfg_data_p);
> while (data == CFG_RETRY_STATUS && timeout--) {
> + /*
> + * CRS state is set in CFG_RD status register
> + * This will handle the case where CFG_RETRY_STATUS is
> + * valid config data.
> + */
> + status = iproc_pcie_read_reg(pcie, IPROC_PCIE_CFG_RD_STATUS);
> + if (status != CFG_RD_CRS)
> + return data;
> +
> udelay(1);
> data = readl(cfg_data_p);
> }
> @@ -576,7 +595,7 @@ static int iproc_pcie_config_read(struct pci_bus *bus, unsigned int devfn,
> if (!cfg_data_p)
> return PCIBIOS_DEVICE_NOT_FOUND;
>
> - data = iproc_pcie_cfg_retry(cfg_data_p);
> + data = iproc_pcie_cfg_retry(pcie, cfg_data_p);
>
> *val = data;
> if (size <= 2)
> --
> 2.7.4
>

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