RE: [PATCH v2] PCI: cadence: Clear FLR in device capabilities register

[Parshuram Raju Thombare <pthombar@cadence.com>]

Ping !

Regards,
Parshuram Thombare

>-----Original Message-----
>From: Parshuram Raju Thombare <pthombar@cadence.com>
>Sent: Tuesday, November 16, 2021 1:09 PM
>To: bhelgaas@google.com; kishon@ti.com; Tom Joseph
><tjoseph@cadence.com>; lorenzo.pieralisi@arm.com; robh@kernel.org;
>kw@linux.com
>Cc: linux-omap@vger.kernel.org; linux-pci@vger.kernel.org; linux-arm-
>kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Milind Parab
><mparab@cadence.com>; Parshuram Raju Thombare
><pthombar@cadence.com>
>Subject: [PATCH v2] PCI: cadence: Clear FLR in device capabilities register
>
>From: Parshuram Thombare <pthombar@cadence.com>
>
>Clear FLR (Function Level Reset) from device capabilities
>registers for all physical functions.
>
>During FLR, the Margining Lane Status and Margining Lane Control
>registers should not be reset, as per PCIe specification.
>However, the controller incorrectly resets these registers upon FLR.
>This causes PCISIG compliance FLR test to fail. Hence preventing
>all functions from advertising FLR support if flag quirk_disable_flr
>is set.
>
>Signed-off-by: Parshuram Thombare <pthombar@cadence.com>
>---
>Changes since v1:
>Changes suggested by Bjorn in the description.
>
>---
> drivers/pci/controller/cadence/pci-j721e.c       |  3 +++
> drivers/pci/controller/cadence/pcie-cadence-ep.c | 18 +++++++++++++++++-
> drivers/pci/controller/cadence/pcie-cadence.h    |  3 +++
> 3 files changed, 23 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/pci/controller/cadence/pci-j721e.c
>b/drivers/pci/controller/cadence/pci-j721e.c
>index ffb176d..635e36c 100644
>--- a/drivers/pci/controller/cadence/pci-j721e.c
>+++ b/drivers/pci/controller/cadence/pci-j721e.c
>@@ -70,6 +70,7 @@ struct j721e_pcie_data {
> 	enum j721e_pcie_mode	mode;
> 	unsigned int		quirk_retrain_flag:1;
> 	unsigned int		quirk_detect_quiet_flag:1;
>+	unsigned int		quirk_disable_flr:1;
> 	u32			linkdown_irq_regfield;
> 	unsigned int		byte_access_allowed:1;
> };
>@@ -308,6 +309,7 @@ static int cdns_ti_pcie_config_write(struct pci_bus *bus,
>unsigned int devfn,
> static const struct j721e_pcie_data j7200_pcie_ep_data = {
> 	.mode = PCI_MODE_EP,
> 	.quirk_detect_quiet_flag = true,
>+	.quirk_disable_flr = true,
> };
>
> static const struct j721e_pcie_data am64_pcie_rc_data = {
>@@ -510,6 +512,7 @@ static int j721e_pcie_probe(struct platform_device
>*pdev)
> 			goto err_get_sync;
> 		}
> 		ep->quirk_detect_quiet_flag = data->quirk_detect_quiet_flag;
>+		ep->quirk_disable_flr = data->quirk_disable_flr;
>
> 		cdns_pcie = &ep->pcie;
> 		cdns_pcie->dev = dev;
>diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c
>b/drivers/pci/controller/cadence/pcie-cadence-ep.c
>index 88e05b9..4b1c4bc 100644
>--- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
>+++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
>@@ -565,7 +565,8 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
> 	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
> 	struct cdns_pcie *pcie = &ep->pcie;
> 	struct device *dev = pcie->dev;
>-	int ret;
>+	int max_epfs = sizeof(epc->function_num_map) * 8;
>+	int ret, value, epf;
>
> 	/*
> 	 * BIT(0) is hardwired to 1, hence function 0 is always enabled
>@@ -573,6 +574,21 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
> 	 */
> 	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, epc-
>>function_num_map);
>
>+	if (ep->quirk_disable_flr) {
>+		for (epf = 0; epf < max_epfs; epf++) {
>+			if (!(epc->function_num_map & BIT(epf)))
>+				continue;
>+
>+			value = cdns_pcie_ep_fn_readl(pcie, epf,
>+
>	CDNS_PCIE_EP_FUNC_DEV_CAP_OFFSET +
>+					PCI_EXP_DEVCAP);
>+			value &= ~PCI_EXP_DEVCAP_FLR;
>+			cdns_pcie_ep_fn_writel(pcie, epf,
>+
>	CDNS_PCIE_EP_FUNC_DEV_CAP_OFFSET +
>+					PCI_EXP_DEVCAP, value);
>+		}
>+	}
>+
> 	ret = cdns_pcie_start_link(pcie);
> 	if (ret) {
> 		dev_err(dev, "Failed to start link\n");
>diff --git a/drivers/pci/controller/cadence/pcie-cadence.h
>b/drivers/pci/controller/cadence/pcie-cadence.h
>index 262421e..e978e7c 100644
>--- a/drivers/pci/controller/cadence/pcie-cadence.h
>+++ b/drivers/pci/controller/cadence/pcie-cadence.h
>@@ -123,6 +123,7 @@
>
> #define CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET	0x90
> #define CDNS_PCIE_EP_FUNC_MSIX_CAP_OFFSET	0xb0
>+#define CDNS_PCIE_EP_FUNC_DEV_CAP_OFFSET	0xc0
> #define CDNS_PCIE_EP_FUNC_SRIOV_CAP_OFFSET	0x200
>
> /*
>@@ -357,6 +358,7 @@ struct cdns_pcie_epf {
>  *        minimize time between read and write
>  * @epf: Structure to hold info about endpoint function
>  * @quirk_detect_quiet_flag: LTSSM Detect Quiet min delay set as quirk
>+ * @quirk_disable_flr: Disable FLR (Function Level Reset) quirk flag
>  */
> struct cdns_pcie_ep {
> 	struct cdns_pcie	pcie;
>@@ -372,6 +374,7 @@ struct cdns_pcie_ep {
> 	spinlock_t		lock;
> 	struct cdns_pcie_epf	*epf;
> 	unsigned int		quirk_detect_quiet_flag:1;
>+	unsigned int		quirk_disable_flr:1;
> };
>
>
>--
>1.9.1