[15/16] PCI/DPC: Wait for reset complete

Commit Message

Keith Busch Aug. 31, 2018, 9:26 p.m. UTC

DPC is only for error recovery. Since we're not removing the topology
and relying on link state interrupts to re-enumerate anymore, the dpc
reset handler has to implement the required reset timings and checks.

Signed-off-by: Keith Busch <[e-mail]>
---
 drivers/pci/pcie/dpc.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

Comments

Sinan Kaya Aug. 31, 2018, 10:15 p.m. UTC | #1

On 8/31/2018 2:26 PM, Keith Busch wrote:
> 	/*
> +	 * PCIe 4.0r1 6.6.1, a component must enter LTSSM Detect within 20ms,
> +	 * after which we should expect an link active if the reset was
> +	 * successful. If so, software must wait a minimum 100ms before sending
> +	 * configuration requests to devices downstream this port.
> +	 *
> +	 * If the link fails to activate, either the device was physically
> +	 * removed or the link is permanently failed.
> +	 */
> +	msleep(20);
> +	if (!pcie_wait_for_link(pdev, true))
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	msleep(100);

Can you move these wait statements and spec reference inside the 
pcie_wait_for_link() function?

Nit. There are some whitespace changes in this file.

Patch

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 93ce26191a2b..34bac3e2beac 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -66,32 +66,38 @@  static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
 
 static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
 {
-	struct dpc_dev *dpc;
-	struct pcie_device *pciedev;
-	struct device *devdpc;
-
-	u16 cap;
+	struct device *dev = pcie_port_find_device(pdev, PCIE_PORT_SERVICE_DPC);
+	struct pcie_device *pciedev = to_pcie_device(dev);
+	struct dpc_dev *dpc = get_service_data(pciedev);
+	u16 cap = dpc->cap_pos;
 
 	/*
 	 * DPC disables the Link automatically in hardware, so it has
 	 * already been reset by the time we get here.
-	 */
-	devdpc = pcie_port_find_device(pdev, PCIE_PORT_SERVICE_DPC);
-	pciedev = to_pcie_device(devdpc);
-	dpc = get_service_data(pciedev);
-	cap = dpc->cap_pos;
-
-	/*
+	 *
 	 * Wait until the Link is inactive, then clear DPC Trigger Status
 	 * to allow the Port to leave DPC.
 	 */
 	pcie_wait_for_link(pdev, false);
-
 	if (dpc->rp_extensions && dpc_wait_rp_inactive(dpc))
 		return PCI_ERS_RESULT_DISCONNECT;
 
 	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
 			      PCI_EXP_DPC_STATUS_TRIGGER);
+	/*
+	 * PCIe 4.0r1 6.6.1, a component must enter LTSSM Detect within 20ms,
+	 * after which we should expect an link active if the reset was
+	 * successful. If so, software must wait a minimum 100ms before sending
+	 * configuration requests to devices downstream this port.
+	 *
+	 * If the link fails to activate, either the device was physically
+	 * removed or the link is permanently failed.
+	 */
+	msleep(20);
+	if (!pcie_wait_for_link(pdev, true))
+		return PCI_ERS_RESULT_DISCONNECT;
+	msleep(100);
+
 	if (pdev->subordinate)
 		pdev->subordinate->error_state = pci_channel_io_normal;
 	return PCI_ERS_RESULT_RECOVERED;