intel_th: gth: Fix the window switching sequence

Commit 8116db57 ("intel_th: Add switch triggering support") added
a trigger assertion of the CTS, but forgot to de-assert it at the end
of the sequence. This results in window switches randomly not happening.

Fix that by de-asserting the trigger at the end of the window switch
sequence.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Fixes: 8116db57 ("intel_th: Add switch triggering support")
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191028070651.9770-2-alexander.shishkin@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/intel_th/gth.c

@@ -626,6 +626,9 @@ static void intel_th_gth_switch(struct intel_th_device *thdev,
 	if (!count)
 		dev_dbg(&thdev->dev, "timeout waiting for CTS Trigger\n");
 
+	/* De-assert the trigger */
+	iowrite32(0, gth->base + REG_CTS_CTL);
+
 	intel_th_gth_stop(gth, output, false);
 	intel_th_gth_start(gth, output);
 }