[Intel-gfx] [PATCH-V2 1/2] drm/i915: add callback to enable/disable codec wakeup

[Jani Nikula]

On Tue, 28 Apr 2015, han.lu at intel.com wrote:
> From: "Lu, Han" <han.lu at intel.com>
>
> In SKL, HDMI/DP codec and PCH HD Audio Controller are in different
> power wells, so it's necessary to reset display audio codecs when
> power well on, otherwise display audio codecs will disappear when
> resume from low power state.
> The reset step when power on is:
>     enable codec wakeup -> azx_init_chip() -> disable codec wakeup
>
> The callback is defined in drivers/gpu/drm/i915/.
> The caller is in sound/pci/hda/.

Han Lu, two more things:

First, is there any chance the chicken bit register is mirrored in the
audio device mmio bar? If yes, you could use it directly in the audio
driver, and we could drop patch 1/2...

Second, looking at the audio driver code for the usage of this callback
in patch 2/2, I don't think the locking and refcounting add any
value. Especially since you ignore the refcounting for disable. You're
the only user, and anything beyond that would be broken anyway, with or
without refcounting or locking. In fact, I'd like to push back the
locking and refcounting to audio driver side, where you may realize they
are not needed at all. Thus, I propose this as patch 1/2:

>From b06bf55b94cdbfad8ec35923b2b657674472cce5 Mon Sep 17 00:00:00 2001
From: "Lu, Han" <han.lu at intel.com>
Date: Tue, 28 Apr 2015 17:03:08 +0300
Subject: [PATCH] drm/i915/audio: add codec wakeup override enabled/disable
 callback
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Cc: Jani Nikula <jani.nikula at intel.com>

Add support for enabling codec wakeup override signal to allow
re-enumeration of the controller on SKL after resume from low power
state.

v3 by Jani: Simplify to only support toggling the appropriate chicken
bit.

Signed-off-by: Lu, Han <han.lu at intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h    |  3 +++
 drivers/gpu/drm/i915/intel_audio.c | 27 +++++++++++++++++++++++++++
 include/drm/i915_component.h       |  1 +
 3 files changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 36805b64036b..435c372d001e 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6881,6 +6881,9 @@ enum skl_disp_power_wells {
 #define   AUDIO_CP_READY(trans)		((1 << 1) << ((trans) * 4))
 #define   AUDIO_ELD_VALID(trans)	((1 << 0) << ((trans) * 4))
 
+#define HSW_AUD_CHICKENBIT			0x65f10
+#define   SKL_AUD_CODEC_WAKE_SIGNAL		(1 << 15)
+
 /* HSW Power Wells */
 #define HSW_PWR_WELL_BIOS			0x45400 /* CTL1 */
 #define HSW_PWR_WELL_DRIVER			0x45404 /* CTL2 */
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index f72e93a45e11..ceb232870d5a 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -474,6 +474,32 @@ static void i915_audio_component_put_power(struct device *dev)
 	intel_display_power_put(dev_to_i915(dev), POWER_DOMAIN_AUDIO);
 }
 
+static void i915_audio_component_codec_wake_override(struct device *dev,
+						     bool enable)
+{
+	struct drm_i915_private *dev_priv = dev_to_i915(dev);
+	u32 tmp;
+
+	if (!IS_SKYLAKE(dev_priv))
+		return;
+
+	/*
+	 * Enable/disable generating the codec wake signal, overriding the
+	 * internal logic to generate the codec wake to controller.
+	 */
+	tmp = I915_READ(HSW_AUD_CHICKENBIT);
+	tmp &= ~SKL_AUD_CODEC_WAKE_SIGNAL;
+	I915_WRITE(HSW_AUD_CHICKENBIT, tmp);
+	usleep_range(1000, 1500);
+
+	if (enable) {
+		tmp = I915_READ(HSW_AUD_CHICKENBIT);
+		tmp |= SKL_AUD_CODEC_WAKE_SIGNAL;
+		I915_WRITE(HSW_AUD_CHICKENBIT, tmp);
+		usleep_range(1000, 1500);
+	}
+}
+
 /* Get CDCLK in kHz  */
 static int i915_audio_component_get_cdclk_freq(struct device *dev)
 {
@@ -495,6 +521,7 @@ static const struct i915_audio_component_ops i915_audio_component_ops = {
 	.owner		= THIS_MODULE,
 	.get_power	= i915_audio_component_get_power,
 	.put_power	= i915_audio_component_put_power,
+	.codec_wake_override = i915_audio_component_codec_wake_override,
 	.get_cdclk_freq	= i915_audio_component_get_cdclk_freq,
 };
 
diff --git a/include/drm/i915_component.h b/include/drm/i915_component.h
index 3e2f22e5bf3c..c9a8b64aa33b 100644
--- a/include/drm/i915_component.h
+++ b/include/drm/i915_component.h
@@ -31,6 +31,7 @@ struct i915_audio_component {
 		struct module *owner;
 		void (*get_power)(struct device *);
 		void (*put_power)(struct device *);
+		void (*codec_wake_override)(struct device *, bool enable);
 		int (*get_cdclk_freq)(struct device *);
 	} *ops;
 };
-- 
2.1.4