Merge branch 'pci/doe'
- Wait up to 1 second for DOE Busy bit to clear before writing a request to
the mailbox to avoid failures if the mailbox is still busy from a
previous transfer (Gregory Price)
* pci/doe:
PCI/DOE: Poll DOE Busy bit for up to 1 second in pci_doe_send_req()
diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
index 652d63d..7bd7892 100644
--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -146,6 +146,7 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
{
struct pci_dev *pdev = doe_mb->pdev;
int offset = doe_mb->cap_offset;
+ unsigned long timeout_jiffies;
size_t length, remainder;
u32 val;
int i;
@@ -155,8 +156,19 @@ static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
* someone other than Linux (e.g. firmware) is using the mailbox. Note
* it is expected that firmware and OS will negotiate access rights via
* an, as yet to be defined, method.
+ *
+ * Wait up to one PCI_DOE_TIMEOUT period to allow the prior command to
+ * finish. Otherwise, simply error out as unable to field the request.
+ *
+ * PCIe r6.2 sec 6.30.3 states no interrupt is raised when the DOE Busy
+ * bit is cleared, so polling here is our best option for the moment.
*/
- pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
+ timeout_jiffies = jiffies + PCI_DOE_TIMEOUT;
+ do {
+ pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
+ } while (FIELD_GET(PCI_DOE_STATUS_BUSY, val) &&
+ !time_after(jiffies, timeout_jiffies));
+
if (FIELD_GET(PCI_DOE_STATUS_BUSY, val))
return -EBUSY;
