[Linuxptp-devel] [PATCH v2 2/4] Drop support for old kernels returning zero frequency.

[Miroslav L. <mli...@re...>]

Kernels before 3.10 had a bug in reading of the system clock frequency,
which was worked around by commit da347d7a36f2 ("ptp4l: Set clock
frequency on start").

Drop this workaround and support for the old kernels to make
clockadj_get_freq() useful.

Signed-off-by: Miroslav Lichvar <mli...@re...>
---
 clock.c   | 7 -------
 phc2sys.c | 4 ----
 ts2phc.c  | 7 -------
 3 files changed, 18 deletions(-)

diff --git a/clock.c b/clock.c
index d37bb87..46ac9c2 100644
--- a/clock.c
+++ b/clock.c
@@ -1144,12 +1144,6 @@ struct clock *clock_create(enum clock_type type, struct config *config,
 
 	if (c->clkid != CLOCK_INVALID) {
 		fadj = (int) clockadj_get_freq(c->clkid);
-		/* Due to a bug in older kernels, the reading may silently fail
-		   and return 0. Set the frequency back to make sure fadj is
-		   the actual frequency of the clock. */
-		if (!c->free_running) {
-			clockadj_set_freq(c->clkid, fadj);
-		}
 		/* Disable write phase mode if not implemented by driver */
 		if (c->write_phase_mode && !phc_has_writephase(c->clkid)) {
 			pr_err("clock does not support write phase mode");
@@ -1755,7 +1749,6 @@ int clock_switch_phc(struct clock *c, int phc_index)
 		return -1;
 	}
 	fadj = (int) clockadj_get_freq(clkid);
-	clockadj_set_freq(clkid, fadj);
 	servo = servo_create(c->config, c->servo_type, -fadj, max_adj, 0);
 	if (!servo) {
 		pr_err("Switching PHC, failed to create clock servo");
diff --git a/phc2sys.c b/phc2sys.c
index 8d2624f..ebc43e5 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -128,10 +128,6 @@ static struct servo *servo_add(struct phc2sys_private *priv,
 
 	clockadj_init(clock->clkid);
 	ppb = clockadj_get_freq(clock->clkid);
-	/* The reading may silently fail and return 0, reset the frequency to
-	   make sure ppb is the actual frequency of the clock. */
-	if (!priv->free_running)
-		clockadj_set_freq(clock->clkid, ppb);
 	if (clock->clkid == CLOCK_REALTIME) {
 		sysclk_set_leap(0);
 		max_ppb = sysclk_max_freq();
diff --git a/ts2phc.c b/ts2phc.c
index f7a57e4..f345370 100644
--- a/ts2phc.c
+++ b/ts2phc.c
@@ -129,13 +129,6 @@ static struct servo *ts2phc_servo_create(struct ts2phc_private *priv,
 	int fadj, max_adj;
 
 	fadj = (int) clockadj_get_freq(clock->clkid);
-	/* Due to a bug in older kernels, the reading may silently fail
-	 * and return 0. Set the frequency back to make sure fadj is
-	 * the actual frequency of the clock.
-	 */
-	if (!clock->no_adj) {
-		clockadj_set_freq(clock->clkid, fadj);
-	}
 
 	max_adj = phc_max_adj(clock->clkid);
 
-- 
2.37.3