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Merge branch 'pci/doe'

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- 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()
This commit is contained in:
Bjorn Helgaas
2024-11-25 13:40:43 -06:00
parent d957ff7aca 86efc62d03
commit 73bdd7304a
1 changed files with 13 additions and 1 deletions
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14
drivers/pci/doe.c
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@@ -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;