From: Stanislav Spassov <stanspas@xxxxxxxxx>
_DSM Function 9 returns device readiness durations in microseconds.
Without this fix, integer truncation could cause msleep()-ing for up to
999us less than actually requested by the firmware.
Specifically, if the firmware specifies a 500us delay, msleep(0) would
be invoked by the users of the delay values optimized here.
Signed-off-by: Stanislav Spassov <stanspas@xxxxxxxxx>
---
drivers/pci/pci-acpi.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a8fa13d6089d..508924377bff 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -1219,6 +1219,11 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev,
acpi_handle handle)
{
struct pci_host_bridge *bridge = pci_find_host_bridge(pdev->bus);
+ /*
+ * _DSM 9 provides values in microseconds, but the kernel uses msleep()
+ * when waiting, so the code below rounds up when setting value in ms
+ */
+ u64 value_us;
int value;
union acpi_object *obj, *elements;
@@ -1233,12 +1238,18 @@ static void pci_acpi_optimize_delay(struct pci_dev *pdev,
if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 5) {
elements = obj->package.elements;
if (elements[0].type == ACPI_TYPE_INTEGER) {
- value = (int)elements[0].integer.value / 1000;
+ value_us = elements[0].integer.value;
+ value = (int)(value_us / 1000);
+ if (value_us % 1000 > 0)
+ value++;
if (value < PCI_PM_D3COLD_WAIT)
pdev->d3cold_delay = value;
}
if (elements[3].type == ACPI_TYPE_INTEGER) {
- value = (int)elements[3].integer.value / 1000;
+ value_us = elements[3].integer.value;
+ value = (int)(value_us / 1000);
+ if (value_us % 1000 > 0)
+ value++;
if (value < PCI_PM_D3_WAIT)
pdev->d3_delay = value;
}
--
2.25.1
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
