ALSA: hda - restore BCLK M/N value as per CDCLK for HSW/BDW display HDA controller

For HSW/BDW display HD-A controller, hda_set_bclk() is defined to set BCLK
by programming the M/N values as per the core display clock (CDCLK) queried from
i915 display driver.

And the audio driver will also set BCLK in azx_first_init() since the display
driver can turn off the shared power in boot phase if only eDP is connected
and M/N values will be lost and must be reprogrammed.

Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 55 insertions, 0 deletions

diff --git a/sound/pci/hda/hda_i915.c b/sound/pci/hda/hda_i915.c
index e9e8a4a4a9a1..8b4940ba33d6 100644
--- a/sound/pci/hda/hda_i915.c
+++ b/sound/pci/hda/hda_i915.c
@@ -20,10 +20,20 @@
 #include <linux/module.h>
 #include <sound/core.h>
 #include <drm/i915_powerwell.h>
+#include "hda_priv.h"
 #include "hda_i915.h"
 
+/* Intel HSW/BDW display HDA controller Extended Mode registers.
+ * EM4 (M value) and EM5 (N Value) are used to convert CDClk (Core Display
+ * Clock) to 24MHz BCLK: BCLK = CDCLK * M / N
+ * The values will be lost when the display power well is disabled.
+ */
+#define ICH6_REG_EM4			0x100c
+#define ICH6_REG_EM5			0x1010
+
 static int (*get_power)(void);
 static int (*put_power)(void);
+static int (*get_cdclk)(void);
 
 int hda_display_power(bool enable)
 {
@@ -38,6 +48,43 @@ int hda_display_power(bool enable)
 		return put_power();
 }
 
+void haswell_set_bclk(struct azx *chip)
+{
+	int cdclk_freq;
+	unsigned int bclk_m, bclk_n;
+
+	if (!get_cdclk)
+		return;
+
+	cdclk_freq = get_cdclk();
+	switch (cdclk_freq) {
+	case 337500:
+		bclk_m = 16;
+		bclk_n = 225;
+		break;
+
+	case 450000:
+	default: /* default CDCLK 450MHz */
+		bclk_m = 4;
+		bclk_n = 75;
+		break;
+
+	case 540000:
+		bclk_m = 4;
+		bclk_n = 90;
+		break;
+
+	case 675000:
+		bclk_m = 8;
+		bclk_n = 225;
+		break;
+	}
+
+	azx_writew(chip, EM4, bclk_m);
+	azx_writew(chip, EM5, bclk_n);
+}
+
+
 int hda_i915_init(void)
 {
 	int err = 0;
@@ -55,6 +102,10 @@ int hda_i915_init(void)
 		return -ENODEV;
 	}
 
+	get_cdclk = symbol_request(i915_get_cdclk_freq);
+	if (!get_cdclk)	/* may have abnormal BCLK and audio playback rate */
+		pr_warn("hda-i915: get_cdclk symbol get fail\n");
+
 	pr_debug("HDA driver get symbol successfully from i915 module\n");
 
 	return err;
@@ -70,6 +121,10 @@ int hda_i915_exit(void)
 		symbol_put(i915_release_power_well);
 		put_power = NULL;
 	}
+	if (get_cdclk) {
+		symbol_put(i915_get_cdclk_freq);
+		get_cdclk = NULL;
+	}
 
 	return 0;
 }