intel_th: Wait until port is in reset before programming it

[ Upstream commit ab1afed ] Some devices don't drain their pipelines if we don't make sure that the corresponding output port is in reset before programming it for a new trace capture, resulting in bits of old trace appearing in the new trace capture. Fix that by explicitly making sure the reset is asserted before programming new trace capture. Reviewed-by: Andy Shevchenko <[email protected]> Signed-off-by: Alexander Shishkin <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
imaami · Jul 20, 2021 · 524449a · 524449a
1 parent da26175
commit 524449a
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diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
@@ -223,6 +223,22 @@ static ssize_t port_show(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR_RO(port);
 
+static void intel_th_trace_prepare(struct intel_th_device *thdev)
+{
+	struct intel_th_device *hub = to_intel_th_hub(thdev);
+	struct intel_th_driver *hubdrv = to_intel_th_driver(hub->dev.driver);
+
+	if (hub->type != INTEL_TH_SWITCH)
+		return;
+
+	if (thdev->type != INTEL_TH_OUTPUT)
+		return;
+
+	pm_runtime_get_sync(&thdev->dev);
+	hubdrv->prepare(hub, &thdev->output);
+	pm_runtime_put(&thdev->dev);
+}
+
 static int intel_th_output_activate(struct intel_th_device *thdev)
 {
 	struct intel_th_driver *thdrv =
@@ -243,6 +259,7 @@ static int intel_th_output_activate(struct intel_th_device *thdev)
 	if (ret)
 		goto fail_put;
 
+	intel_th_trace_prepare(thdev);
 	if (thdrv->activate)
 		ret = thdrv->activate(thdev);
 	else

diff --git a/drivers/hwtracing/intel_th/gth.c b/drivers/hwtracing/intel_th/gth.c
@@ -521,6 +521,21 @@ static void gth_tscu_resync(struct gth_device *gth)
 	iowrite32(reg, gth->base + REG_TSCU_TSUCTRL);
 }
 
+static void intel_th_gth_prepare(struct intel_th_device *thdev,
+				 struct intel_th_output *output)
+{
+	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
+	int count;
+
+	/*
+	 * Wait until the output port is in reset before we start
+	 * programming it.
+	 */
+	for (count = GTH_PLE_WAITLOOP_DEPTH;
+	     count && !(gth_output_get(gth, output->port) & BIT(5)); count--)
+		cpu_relax();
+}
+
 /**
  * intel_th_gth_enable() - enable tracing to an output device
  * @thdev:	GTH device
@@ -742,6 +757,7 @@ static struct intel_th_driver intel_th_gth_driver = {
 	.assign		= intel_th_gth_assign,
 	.unassign	= intel_th_gth_unassign,
 	.set_output	= intel_th_gth_set_output,
+	.prepare	= intel_th_gth_prepare,
 	.enable		= intel_th_gth_enable,
 	.disable	= intel_th_gth_disable,
 	.driver	= {

diff --git a/drivers/hwtracing/intel_th/intel_th.h b/drivers/hwtracing/intel_th/intel_th.h
@@ -140,6 +140,7 @@ intel_th_output_assigned(struct intel_th_device *thdev)
  * @remove:	remove method
  * @assign:	match a given output type device against available outputs
  * @unassign:	deassociate an output type device from an output port
+ * @prepare:	prepare output port for tracing
  * @enable:	enable tracing for a given output device
  * @disable:	disable tracing for a given output device
  * @irq:	interrupt callback
@@ -161,6 +162,8 @@ struct intel_th_driver {
 					  struct intel_th_device *othdev);
 	void			(*unassign)(struct intel_th_device *thdev,
 					    struct intel_th_device *othdev);
+	void			(*prepare)(struct intel_th_device *thdev,
+					   struct intel_th_output *output);
 	void			(*enable)(struct intel_th_device *thdev,
 					  struct intel_th_output *output);
 	void			(*disable)(struct intel_th_device *thdev,