On 7/18/2023 19:45, Bjorn Helgaas wrote:
[+cc Paul, Vinicius, Kai-Heng, Guilherme]
On Mon, Jul 17, 2023 at 08:19:27PM +0300, Sasha Neftin wrote:
With the 10us interval, we were seeing PTM transactions taking around 12us.
With the 1us interval, PTM dialogs took around 2us. Checked with the PCIe
sniffer.
Fixes: a90ec8483732 ("igc: Add support for PTP getcrosststamp()")
Suggested-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
Signed-off-by: Sasha Neftin <sasha.neftin@xxxxxxxxx>
---
drivers/net/ethernet/intel/igc/igc_defines.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index 44a507029946..c3722f524ea7 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -549,7 +549,7 @@
#define IGC_PTM_CTRL_SHRT_CYC(usec) (((usec) & 0x2f) << 2)
#define IGC_PTM_CTRL_PTM_TO(usec) (((usec) & 0xff) << 8)
-#define IGC_PTM_SHORT_CYC_DEFAULT 10 /* Default Short/interrupted cycle interval */
+#define IGC_PTM_SHORT_CYC_DEFAULT 1 /* Default short cycle interval */
Not related to *this* patch, but from looking at igc_ptp_reset(),
where IGC_PTM_SHORT_CYC_DEFAULT is used,
/* PCIe PTM Control */
#define IGC_PTM_CTRL_START_NOW BIT(29) /* Start PTM Now */
#define IGC_PTM_CTRL_EN BIT(30) /* Enable PTM */
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;
wr32(IGC_PTM_CTRL, ctrl);
Obviously this must be implementation-specific PTM configuration,
which is fine. But I assume even though this sets IGC_PTM_CTRL_EN and
IGC_PTM_CTRL_START_NOW, the device will not actually send PTM Request
messages unless the architected PTM Enable bit in the PTM Capability
is set (PCIe r6.0, sec 7.9.15.3). Right?
Right.
I'm asking because Kai-Heng has been working on issues where
Unsupported Request errors are reported because some devices seem to
send PTM Requests when we don't think they should. See
https://lore.kernel.org/r/20230714050541.2765246-1-kai.heng.feng@xxxxxxxxxxxxx
I know. This is a different problem. (I can not reproduce, we will try
to get HP dock). We will think how to help here.
#define IGC_PTM_CYC_TIME_DEFAULT 5 /* Default PTM cycle time */
#define IGC_PTM_TIMEOUT_DEFAULT 255 /* Default timeout for PTM errors */
