intel_reg_dumper: enable the power well

The intel_reg_dumper tool reads a lot of display registers. If we
don't turn on the power well, dmesg will get flooded with tons of
messages about unclaimed registers. So here we enable the "Debug"
power well register and then restore its state later. It's impossible
to guarantee that other things won't mess with the debug register
between our put and get calls, but at least we're trying our best to
keep things working fine, and it's the debug register anyway.

As far as I know, nothing else uses the Debug register for anything,
so we should be safe for now.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

1 files changed, 42 insertions, 1 deletions

diff --git a/tools/intel_reg_dumper.c b/tools/intel_reg_dumper.c
index 56504694..1d44660f 100644
--- a/tools/intel_reg_dumper.c
+++ b/tools/intel_reg_dumper.c
@@ -2798,6 +2798,43 @@ intel_dump_other_regs(void)
 	}
 }
 
+/*
+ * This program reads a lot of display registers. If we don't turn on the power
+ * well, dmesg will get flooded with tons of messages about unclaimed registers.
+ * So here we enable the "Debug" power well register and then restore its state
+ * later. It's impossible to guarantee that other things won't mess with the
+ * debug register between our put and get calls, but at least we're trying our
+ * best to keep things working fine, and it's the debug register anyway.
+ */
+static uint32_t power_well_get(void)
+{
+	uint32_t ret;
+	int i;
+
+	if (!IS_HASWELL(devid))
+		return 0;
+
+	ret = INREG(HSW_PWR_WELL_CTL4) & HSW_PWR_WELL_ENABLE;
+
+	OUTREG(HSW_PWR_WELL_CTL4, HSW_PWR_WELL_ENABLE);
+
+	for (i = 0; i < 20; i++) {
+		if (INREG(HSW_PWR_WELL_CTL4) & HSW_PWR_WELL_STATE)
+			break;
+		usleep(1000);
+	}
+
+	return ret;
+}
+
+static void power_well_put(uint32_t power_well)
+{
+	if (!IS_HASWELL(devid))
+		return;
+
+	OUTREG(HSW_PWR_WELL_CTL4, power_well);
+}
+
 static void print_usage(void)
 {
 	printf("Usage: intel_reg_dumper [options] [file]\n"
@@ -2813,7 +2850,7 @@ int main(int argc, char** argv)
 	struct pci_device *pci_dev;
 	int opt, n_args;
 	char *file = NULL, *reg_name = NULL;
-	uint32_t reg_val;
+	uint32_t reg_val, power_well;
 
 	while ((opt = getopt(argc, argv, "d:h")) != -1) {
 		switch (opt) {
@@ -2874,6 +2911,8 @@ int main(int argc, char** argv)
 			intel_check_pch();
 	}
 
+	power_well = power_well_get();
+
 	if (IS_HASWELL(devid)) {
 		intel_dump_regs(haswell_debug_regs);
 	} else if (IS_GEN5(devid) || IS_GEN6(devid) || IS_IVYBRIDGE(devid)) {
@@ -2890,6 +2929,8 @@ int main(int argc, char** argv)
 	if (IS_GEN6(devid) || IS_GEN7(devid))
 		intel_dump_regs(gen6_rp_debug_regs);
 
+	power_well_put(power_well);
+
 	intel_register_access_fini();
 	return 0;
 }