Dear Christopher,
Thank you for the patch.
Am 07.08.24 um 02:30 schrieb christopher.s.h...@intel.com:
From: Christopher S M Hall <christopher.s.h...@intel.com>
Writing to clear the PTM status 'valid' bit while the PTM cycle is
triggered results in unreliable PTM operation. To fix this, clear the
PTM 'trigger' and status after each PTM transaction.
I do not understand, why the *valid* bit is not needed anymore, and why
it’s the trigger bit seems to do the same task. It’d be great if you
elaborated.
Is that also documented in the dataheet?
The issue can be reproduced with the following:
$ sudo phc2sys -R 1000 -O 0 -i tsn0 -m
Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to
quickly reproduce the issue.
PHC2SYS exits with:
"ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction
fails
Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Signed-off-by: Christopher S M Hall <christopher.s.h...@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkow...@linux.intel.com>
---
drivers/net/ethernet/intel/igc/igc_defines.h | 1 +
drivers/net/ethernet/intel/igc/igc_ptp.c | 70 ++++++++++++--------
2 files changed, 42 insertions(+), 29 deletions(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h
b/drivers/net/ethernet/intel/igc/igc_defines.h
index 511384f3ec5c..ec191d26c650 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -583,6 +583,7 @@
#define IGC_PTM_STAT_T4M1_OVFL BIT(3) /* T4 minus T1 overflow
*/
#define IGC_PTM_STAT_ADJUST_1ST BIT(4) /* 1588 timer adjusted
during 1st PTM cycle */
#define IGC_PTM_STAT_ADJUST_CYC BIT(5) /* 1588 timer adjusted
during non-1st PTM cycle */
+#define IGC_PTM_STAT_ALL GENMASK(5, 0) /* Used to clear
all status */
/* PCIe PTM Cycle Control */
#define IGC_PTM_CYCLE_CTRL_CYC_TIME(msec) ((msec) & 0x3ff) /* PTM Cycle
Time (msec) */
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c
b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 946edbad4302..00cc80d8d164 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -974,11 +974,38 @@ static void igc_ptm_log_error(struct igc_adapter
*adapter, u32 ptm_stat)
}
}
+static void igc_ptm_trigger(struct igc_hw *hw)
+{
+ u32 ctrl;
+
+ /* To "manually" start the PTM cycle we need to set the
+ * trigger (TRIG) bit
+ */
+ ctrl = rd32(IGC_PTM_CTRL);
+ ctrl |= IGC_PTM_CTRL_TRIG;
+ wr32(IGC_PTM_CTRL, ctrl);
+ /* Perform flush after write to CTRL register otherwise
+ * transaction may not start
+ */
+ wrfl();
+}
+
+static void igc_ptm_reset(struct igc_hw *hw)
+{
+ u32 ctrl;
+
+ ctrl = rd32(IGC_PTM_CTRL);
+ ctrl &= ~IGC_PTM_CTRL_TRIG;
+ wr32(IGC_PTM_CTRL, ctrl);
+ /* Write to clear all status */
+ wr32(IGC_PTM_STAT, IGC_PTM_STAT_ALL);
+}
+
static int igc_phc_get_syncdevicetime(ktime_t *device,
struct system_counterval_t *system,
void *ctx)
{
- u32 stat, t2_curr_h, t2_curr_l, ctrl;
+ u32 stat, t2_curr_h, t2_curr_l;
struct igc_adapter *adapter = ctx;
struct igc_hw *hw = &adapter->hw;
int err, count = 100;
@@ -994,25 +1021,13 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
* are transitory. Repeating the process returns valid
* data eventually.
*/
-
- /* To "manually" start the PTM cycle we need to clear and
- * then set again the TRIG bit.
- */
- ctrl = rd32(IGC_PTM_CTRL);
- ctrl &= ~IGC_PTM_CTRL_TRIG;
- wr32(IGC_PTM_CTRL, ctrl);
- ctrl |= IGC_PTM_CTRL_TRIG;
- wr32(IGC_PTM_CTRL, ctrl);
-
- /* The cycle only starts "for real" when software notifies
- * that it has read the registers, this is done by setting
- * VALID bit.
- */
- wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
+ igc_ptm_trigger(hw);
err = readx_poll_timeout(rd32, IGC_PTM_STAT, stat,
stat, IGC_PTM_STAT_SLEEP,
IGC_PTM_STAT_TIMEOUT);
+ igc_ptm_reset(hw);
+
if (err < 0) {
netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT
register\n");
return err;
@@ -1021,15 +1036,7 @@ static int igc_phc_get_syncdevicetime(ktime_t *device,
if ((stat & IGC_PTM_STAT_VALID) == IGC_PTM_STAT_VALID)
break;
- if (stat & ~IGC_PTM_STAT_VALID) {
- /* An error occurred, log it. */
- igc_ptm_log_error(adapter, stat);
- /* The STAT register is write-1-to-clear (W1C),
- * so write the previous error status to clear it.
- */
- wr32(IGC_PTM_STAT, stat);
- continue;
- }
+ igc_ptm_log_error(adapter, stat);
Could this refactoring be a separate commit?
} while (--count);
if (!count) {
@@ -1255,7 +1262,7 @@ void igc_ptp_stop(struct igc_adapter *adapter)
void igc_ptp_reset(struct igc_adapter *adapter)
{
struct igc_hw *hw = &adapter->hw;
- u32 cycle_ctrl, ctrl;
+ u32 cycle_ctrl, ctrl, stat;
unsigned long flags;
u32 timadj;
@@ -1290,14 +1297,19 @@ void igc_ptp_reset(struct igc_adapter *adapter)
ctrl = IGC_PTM_CTRL_EN |
IGC_PTM_CTRL_START_NOW |
IGC_PTM_CTRL_SHRT_CYC(IGC_PTM_SHORT_CYC_DEFAULT) |
- IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT) |
- IGC_PTM_CTRL_TRIG;
+ IGC_PTM_CTRL_PTM_TO(IGC_PTM_TIMEOUT_DEFAULT);
wr32(IGC_PTM_CTRL, ctrl);
/* Force the first cycle to run. */
- wr32(IGC_PTM_STAT, IGC_PTM_STAT_VALID);
+ igc_ptm_trigger(hw);
+
+ if (readx_poll_timeout_atomic(rd32, IGC_PTM_STAT, stat,
+ stat, IGC_PTM_STAT_SLEEP,
+ IGC_PTM_STAT_TIMEOUT))
+ netdev_err(adapter->netdev, "Timeout reading IGC_PTM_STAT
register\n");
I’d add the timeout value to the message.
+ igc_ptm_reset(hw);
break;
default:
/* No work to do. */
Kind regards,
Paul
