diff mbox series

[net-next,v3] net: mvpp2: tai: warn once if we fail to update our timestamp

Message ID E1tM8cA-006t1i-KF@rmk-PC.armlinux.org.uk (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series [net-next,v3] net: mvpp2: tai: warn once if we fail to update our timestamp | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 8 of 8 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 23 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-12-15--09-00 (tests: 795)

Commit Message

Russell King (Oracle) Dec. 13, 2024, 4:34 p.m. UTC 
The hardware timestamps for packets contain a truncated seconds field,
only containing two bits of seconds. In order to provide the full
number of seconds, we need to keep track of the full hardware clock by
reading it every two seconds.

However, if we fail to read the clock, we silently ignore the error.
Print a warning indicating that the PP2 TAI clock timestamps have
become unreliable.

Reviewed-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
--
v2: correct dev_warn_once() indentation
v3: add '\n'
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Richard Cochran Dec. 14, 2024, 5:14 a.m. UTC | #1 
On Fri, Dec 13, 2024 at 04:34:06PM +0000, Russell King wrote:
> The hardware timestamps for packets contain a truncated seconds field,
> only containing two bits of seconds. In order to provide the full
> number of seconds, we need to keep track of the full hardware clock by
> reading it every two seconds.
> 
> However, if we fail to read the clock, we silently ignore the error.
> Print a warning indicating that the PP2 TAI clock timestamps have
> become unreliable.

Rather than printing a warning that user space might not read, why not
set a flag and stop delivering time stamps until the upper bits are
available once again?

Thanks,
Richard
diff mbox series

Patch

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
index 95862aff49f1..d4e8708a9c76 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
@@ -54,6 +54,7 @@ 
 #define TCSR_CAPTURE_0_VALID		BIT(0)
 
 struct mvpp2_tai {
+	struct device *dev;
 	struct ptp_clock_info caps;
 	struct ptp_clock *ptp_clock;
 	void __iomem *base;
@@ -303,7 +304,8 @@  static long mvpp22_tai_aux_work(struct ptp_clock_info *ptp)
 {
 	struct mvpp2_tai *tai = ptp_to_tai(ptp);
 
-	mvpp22_tai_gettimex64(ptp, &tai->stamp, NULL);
+	if (mvpp22_tai_gettimex64(ptp, &tai->stamp, NULL) < 0)
+		dev_warn_once(tai->dev, "PTP timestamps are unreliable\n");
 
 	return msecs_to_jiffies(2000);
 }
@@ -401,6 +403,7 @@  int mvpp22_tai_probe(struct device *dev, struct mvpp2 *priv)
 
 	spin_lock_init(&tai->lock);
 
+	tai->dev = dev;
 	tai->base = priv->iface_base;
 
 	/* The step size consists of three registers - a 16-bit nanosecond step