diff options
Diffstat (limited to 'drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c')
| -rw-r--r-- | drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c index a2a2d923e60c..df1fc6c719f3 100644 --- a/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_pci.c @@ -21,12 +21,16 @@ #define PUNIT_MAILBOX_BUSY_BIT 31 /* - * The average time to complete some commands is about 40us. The current - * count is enough to satisfy 40us. But when the firmware is very busy, this - * causes timeout occasionally. So increase to deal with some worst case - * scenarios. Most of the command still complete in few us. + * The average time to complete mailbox commands is less than 40us. Most of + * the commands complete in few micro seconds. But the same firmware handles + * requests from all power management features. + * We can create a scenario where we flood the firmware with requests then + * the mailbox response can be delayed for 100s of micro seconds. So define + * two timeouts. One for average case and one for long. + * If the firmware is taking more than average, just call cond_resched(). */ -#define OS_MAILBOX_RETRY_COUNT 100 +#define OS_MAILBOX_TIMEOUT_AVG_US 40 +#define OS_MAILBOX_TIMEOUT_MAX_US 1000 struct isst_if_device { struct mutex mutex; @@ -35,11 +39,13 @@ struct isst_if_device { static int isst_if_mbox_cmd(struct pci_dev *pdev, struct isst_if_mbox_cmd *mbox_cmd) { - u32 retries, data; + s64 tm_delta = 0; + ktime_t tm; + u32 data; int ret; /* Poll for rb bit == 0 */ - retries = OS_MAILBOX_RETRY_COUNT; + tm = ktime_get(); do { ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE, &data); @@ -48,11 +54,14 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) { ret = -EBUSY; + tm_delta = ktime_us_delta(ktime_get(), tm); + if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US) + cond_resched(); continue; } ret = 0; break; - } while (--retries); + } while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US); if (ret) return ret; @@ -74,7 +83,8 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, return ret; /* Poll for rb bit == 0 */ - retries = OS_MAILBOX_RETRY_COUNT; + tm_delta = 0; + tm = ktime_get(); do { ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE, &data); @@ -83,6 +93,9 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) { ret = -EBUSY; + tm_delta = ktime_us_delta(ktime_get(), tm); + if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US) + cond_resched(); continue; } @@ -96,7 +109,7 @@ static int isst_if_mbox_cmd(struct pci_dev *pdev, mbox_cmd->resp_data = data; ret = 0; break; - } while (--retries); + } while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US); return ret; } |