pci: pcie-brcmstb: bring over some robustness improvements from Linux
Since the initial U-Boot driver was ported here from Linux, the latter
has had a few changes for robustness/stability. This patch brings over
two of them:
- Do not attempt to access the configuration space of a PCIe device if
the link has gone down, as that will result in an asynchronous SError
interrupt which will crash U-Boot.
- Wait for the recommended 100ms after PERST# is deasserted.
I sent this patch while debugging a crash involving PCIe, but these
are unrelated improvements. I do not believe that this patch fixes any
real-world bug.
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
diff --git a/drivers/pci/pcie_brcmstb.c b/drivers/pci/pcie_brcmstb.c
index 1de2802..a159952 100644
--- a/drivers/pci/pcie_brcmstb.c
+++ b/drivers/pci/pcie_brcmstb.c
@@ -223,6 +223,10 @@
return 0;
}
+ /* An access to our HW w/o link-up will cause a CPU Abort */
+ if (!brcm_pcie_link_up(pcie))
+ return -EINVAL;
+
/* For devices, write to the config space index register */
idx = PCIE_ECAM_OFFSET(pci_bus, pci_dev, pci_func, 0);
@@ -505,6 +509,12 @@
clrbits_le32(pcie->base + PCIE_RGR1_SW_INIT_1,
RGR1_SW_INIT_1_PERST_MASK);
+ /*
+ * Wait for 100ms after PERST# deassertion; see PCIe CEM specification
+ * sections 2.2, PCIe r5.0, 6.6.1.
+ */
+ mdelay(100);
+
/* Give the RC/EP time to wake up, before trying to configure RC.
* Intermittently check status for link-up, up to a total of 100ms.
*/