drm/i915/dvo: implement get_hw_state

Similar to the sdvo code we poke the dvo encoder whether the output is
active. Safe that dvo encoders are not standardized, so this requires
a new callback into the dvo chip driver.

Hence implement that for all 6 dvo drivers.

v2: With the newly added ns2501 we now have 6 dvo drivers instead of
just 5 ...

Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/dvo_ns2501.c b/drivers/gpu/drm/i915/dvo_ns2501.c
index c4d9f2f..c4a255b 100644
--- a/drivers/gpu/drm/i915/dvo_ns2501.c
+++ b/drivers/gpu/drm/i915/dvo_ns2501.c
@@ -493,6 +493,20 @@
 }
 
 /* set the NS2501 power state */
+static bool ns2501_get_hw_state(struct intel_dvo_device *dvo)
+{
+	unsigned char ch;
+
+	if (!ns2501_readb(dvo, NS2501_REG8, &ch))
+		return false;
+
+	if (ch & NS2501_8_PD)
+		return true;
+	else
+		return false;
+}
+
+/* set the NS2501 power state */
 static void ns2501_dpms(struct intel_dvo_device *dvo, bool enable)
 {
 	bool ok;
@@ -568,6 +582,7 @@
 	.mode_valid = ns2501_mode_valid,
 	.mode_set = ns2501_mode_set,
 	.dpms = ns2501_dpms,
+	.get_hw_state = ns2501_get_hw_state,
 	.dump_regs = ns2501_dump_regs,
 	.destroy = ns2501_destroy,
 };