From: Pali Rohár pali@kernel.org
commit 223dec14a05337a4155f1deed46d2becce4d00fd upstream.
Commit 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value") fixed handling of CRS response and when CRSSVE flag was not enabled it marked CRS response as failed transaction (due to simplicity).
But pci-aardvark.c driver is already waiting up to the PIO_RETRY_CNT count for PIO config response and so we can with a small change implement re-issuing of config requests as described in PCIe base specification.
This change implements re-issuing of config requests when response is CRS. Set upper bound of wait cycles to around PIO_RETRY_CNT, afterwards the transaction is marked as failed and an all-ones value is returned as before.
We do this by returning appropriate error codes from function advk_pcie_check_pio_status(). On CRS we return -EAGAIN and caller then reissues transaction.
Link: https://lore.kernel.org/r/20211005180952.6812-10-kabel@kernel.org Signed-off-by: Pali Rohár pali@kernel.org Signed-off-by: Marek Behún kabel@kernel.org Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Reviewed-by: Marek Behún kabel@kernel.org Signed-off-by: Marek Behún kabel@kernel.org --- drivers/pci/controller/pci-aardvark.c | 67 +++++++++++++++++---------- 1 file changed, 43 insertions(+), 24 deletions(-)
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 6eea7d5aac26..ff243be8410c 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -692,6 +692,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 u32 reg; unsigned int status; char *strcomp_status, *str_posted; + int ret;
reg = advk_readl(pcie, PIO_STAT); status = (reg & PIO_COMPLETION_STATUS_MASK) >> @@ -716,6 +717,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 case PIO_COMPLETION_STATUS_OK: if (reg & PIO_ERR_STATUS) { strcomp_status = "COMP_ERR"; + ret = -EFAULT; break; } /* Get the read result */ @@ -723,9 +725,11 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 *val = advk_readl(pcie, PIO_RD_DATA); /* No error */ strcomp_status = NULL; + ret = 0; break; case PIO_COMPLETION_STATUS_UR: strcomp_status = "UR"; + ret = -EOPNOTSUPP; break; case PIO_COMPLETION_STATUS_CRS: if (allow_crs && val) { @@ -743,6 +747,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 */ *val = CFG_RD_CRS_VAL; strcomp_status = NULL; + ret = 0; break; } /* PCIe r4.0, sec 2.3.2, says: @@ -758,21 +763,24 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 * Request and taking appropriate action, e.g., complete the * Request to the host as a failed transaction. * - * To simplify implementation do not re-issue the Configuration - * Request and complete the Request as a failed transaction. + * So return -EAGAIN and caller (pci-aardvark.c driver) will + * re-issue request again up to the PIO_RETRY_CNT retries. */ strcomp_status = "CRS"; + ret = -EAGAIN; break; case PIO_COMPLETION_STATUS_CA: strcomp_status = "CA"; + ret = -ECANCELED; break; default: strcomp_status = "Unknown"; + ret = -EINVAL; break; }
if (!strcomp_status) - return 0; + return ret;
if (reg & PIO_NON_POSTED_REQ) str_posted = "Non-posted"; @@ -782,7 +790,7 @@ static int advk_pcie_check_pio_status(struct advk_pcie *pcie, bool allow_crs, u3 dev_dbg(dev, "%s PIO Response Status: %s, %#x @ %#x\n", str_posted, strcomp_status, reg, advk_readl(pcie, PIO_ADDR_LS));
- return -EFAULT; + return ret; }
static int advk_pcie_wait_pio(struct advk_pcie *pcie) @@ -790,13 +798,13 @@ static int advk_pcie_wait_pio(struct advk_pcie *pcie) struct device *dev = &pcie->pdev->dev; int i;
- for (i = 0; i < PIO_RETRY_CNT; i++) { + for (i = 1; i <= PIO_RETRY_CNT; i++) { u32 start, isr;
start = advk_readl(pcie, PIO_START); isr = advk_readl(pcie, PIO_ISR); if (!start && isr) - return 0; + return i; udelay(PIO_RETRY_DELAY); }
@@ -1068,6 +1076,7 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where, int size, u32 *val) { struct advk_pcie *pcie = bus->sysdata; + int retry_count; bool allow_crs; u32 reg; int ret; @@ -1110,16 +1119,22 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, /* Program the data strobe */ advk_writel(pcie, 0xf, PIO_WR_DATA_STRB);
- /* Clear PIO DONE ISR and start the transfer */ - advk_writel(pcie, 1, PIO_ISR); - advk_writel(pcie, 1, PIO_START); + retry_count = 0; + do { + /* Clear PIO DONE ISR and start the transfer */ + advk_writel(pcie, 1, PIO_ISR); + advk_writel(pcie, 1, PIO_START);
- ret = advk_pcie_wait_pio(pcie); - if (ret < 0) - goto try_crs; + ret = advk_pcie_wait_pio(pcie); + if (ret < 0) + goto try_crs; + + retry_count += ret; + + /* Check PIO status and get the read result */ + ret = advk_pcie_check_pio_status(pcie, allow_crs, val); + } while (ret == -EAGAIN && retry_count < PIO_RETRY_CNT);
- /* Check PIO status and get the read result */ - ret = advk_pcie_check_pio_status(pcie, allow_crs, val); if (ret < 0) goto fail;
@@ -1151,6 +1166,7 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn, struct advk_pcie *pcie = bus->sysdata; u32 reg; u32 data_strobe = 0x0; + int retry_count; int offset; int ret;
@@ -1192,19 +1208,22 @@ static int advk_pcie_wr_conf(struct pci_bus *bus, u32 devfn, /* Program the data strobe */ advk_writel(pcie, data_strobe, PIO_WR_DATA_STRB);
- /* Clear PIO DONE ISR and start the transfer */ - advk_writel(pcie, 1, PIO_ISR); - advk_writel(pcie, 1, PIO_START); + retry_count = 0; + do { + /* Clear PIO DONE ISR and start the transfer */ + advk_writel(pcie, 1, PIO_ISR); + advk_writel(pcie, 1, PIO_START);
- ret = advk_pcie_wait_pio(pcie); - if (ret < 0) - return PCIBIOS_SET_FAILED; + ret = advk_pcie_wait_pio(pcie); + if (ret < 0) + return PCIBIOS_SET_FAILED;
- ret = advk_pcie_check_pio_status(pcie, false, NULL); - if (ret < 0) - return PCIBIOS_SET_FAILED; + retry_count += ret;
- return PCIBIOS_SUCCESSFUL; + ret = advk_pcie_check_pio_status(pcie, false, NULL); + } while (ret == -EAGAIN && retry_count < PIO_RETRY_CNT); + + return ret < 0 ? PCIBIOS_SET_FAILED : PCIBIOS_SUCCESSFUL; }
static struct pci_ops advk_pcie_ops = {