commit a0e7df335afd2a8a8a688251ffee375b58b6517c
author Alexander Shishkin <alexander.shishkin@linux.intel.com> Fri Feb 24 16:09:40 2017 +0200
committer Alexander Shishkin <alexander.shishkin@linux.intel.com> Fri Aug 25 18:48:00 2017 +0300
tree 6639e55ee5fb65286bde48fdbfa6f4ab16890077
parent 29e15e83a99cdc13d0d38de558fbea641f8fdda8

intel_th: Perform time resync on capture start

On some devices (TH 2.x devices at the moment), the internal time counter
is initially not synchronized to the global crystal clock, so the time
stamps it produces will not be useful. In this case, the driver needs
to force the time counter resync.

This applies the workaround to relevant devices.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

drivers/hwtracing/intel_th/gth.c

diff --git a/drivers/hwtracing/intel_th/gth.c b/drivers/hwtracing/intel_th/gth.c
index 7d9d667..018678e 100644
--- a/drivers/hwtracing/intel_th/gth.c
+++ b/drivers/hwtracing/intel_th/gth.c
@@ -285,16 +285,16 @@
  */
 static int intel_th_gth_reset(struct gth_device *gth)
 {
-	u32 scratchpad;
+	u32 reg;
 	int port, i;
 
-	scratchpad = ioread32(gth->base + REG_GTH_SCRPD0);
-	if (scratchpad & SCRPD_DEBUGGER_IN_USE)
+	reg = ioread32(gth->base + REG_GTH_SCRPD0);
+	if (reg & SCRPD_DEBUGGER_IN_USE)
 		return -EBUSY;
 
 	/* Always save/restore STH and TU registers in S0ix entry/exit */
-	scratchpad |= SCRPD_STH_IS_ENABLED | SCRPD_TRIGGER_IS_ENABLED;
-	iowrite32(scratchpad, gth->base + REG_GTH_SCRPD0);
+	reg |= SCRPD_STH_IS_ENABLED | SCRPD_TRIGGER_IS_ENABLED;
+	iowrite32(reg, gth->base + REG_GTH_SCRPD0);
 
 	/* output ports */
 	for (port = 0; port < 8; port++) {
@@ -512,6 +512,15 @@
 	iowrite32(reg, gth->base + REG_GTH_SCRPD0);
 }
 
+static void gth_tscu_resync(struct gth_device *gth)
+{
+	u32 reg;
+
+	reg = ioread32(gth->base + REG_TSCU_TSUCTRL);
+	reg &= ~TSUCTRL_CTCRESYNC;
+	iowrite32(reg, gth->base + REG_TSCU_TSUCTRL);
+}
+
 /**
  * intel_th_gth_enable() - enable tracing to an output device
  * @thdev:	GTH device
@@ -524,6 +533,7 @@
 				struct intel_th_output *output)
 {
 	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
+	struct intel_th *th = to_intel_th(thdev);
 	u32 scr = 0xfc0000, scrpd;
 	int master;
 
@@ -539,6 +549,9 @@
 	output->active = true;
 	spin_unlock(&gth->gth_lock);
 
+	if (INTEL_TH_CAP(th, tscu_enable))
+		gth_tscu_resync(gth);
+
 	scrpd = ioread32(gth->base + REG_GTH_SCRPD0);
 	scrpd |= output->scratchpad;
 	iowrite32(scrpd, gth->base + REG_GTH_SCRPD0);