drm/i915/audio: Fix audio time stamp programming for DP

Intel hardware is capable of programming the Maud/Naud SDPs on its
own based on real-time clocks. While doing so, it takes care
of any deviations from the theoretical values. Programming the registers
explicitly with static values can interfere with this logic. Therefore,
let the HW decide the Maud and Naud SDPs on it's own.

Cc: stable@vger.kernel.org # v5.17
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8097Co-developed-by: Kai Vehmanen <kai.vehmanen@intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240430091825.733499-1-chaitanya.kumar.borah@intel.com

drivers/gpu/drm/i915/display/intel_audio.c

@@ -76,19 +76,6 @@ struct intel_audio_funcs {
 				       struct intel_crtc_state *crtc_state);
 };
 
-/* DP N/M table */
-#define LC_810M	810000
-#define LC_540M	540000
-#define LC_270M	270000
-#define LC_162M	162000
-
-struct dp_aud_n_m {
-	int sample_rate;
-	int clock;
-	u16 m;
-	u16 n;
-};
-
 struct hdmi_aud_ncts {
 	int sample_rate;
 	int clock;
@@ -96,60 +83,6 @@ struct hdmi_aud_ncts {
 	int cts;
 };
 
-/* Values according to DP 1.4 Table 2-104 */
-static const struct dp_aud_n_m dp_aud_n_m[] = {
-	{ 32000, LC_162M, 1024, 10125 },
-	{ 44100, LC_162M, 784, 5625 },
-	{ 48000, LC_162M, 512, 3375 },
-	{ 64000, LC_162M, 2048, 10125 },
-	{ 88200, LC_162M, 1568, 5625 },
-	{ 96000, LC_162M, 1024, 3375 },
-	{ 128000, LC_162M, 4096, 10125 },
-	{ 176400, LC_162M, 3136, 5625 },
-	{ 192000, LC_162M, 2048, 3375 },
-	{ 32000, LC_270M, 1024, 16875 },
-	{ 44100, LC_270M, 784, 9375 },
-	{ 48000, LC_270M, 512, 5625 },
-	{ 64000, LC_270M, 2048, 16875 },
-	{ 88200, LC_270M, 1568, 9375 },
-	{ 96000, LC_270M, 1024, 5625 },
-	{ 128000, LC_270M, 4096, 16875 },
-	{ 176400, LC_270M, 3136, 9375 },
-	{ 192000, LC_270M, 2048, 5625 },
-	{ 32000, LC_540M, 1024, 33750 },
-	{ 44100, LC_540M, 784, 18750 },
-	{ 48000, LC_540M, 512, 11250 },
-	{ 64000, LC_540M, 2048, 33750 },
-	{ 88200, LC_540M, 1568, 18750 },
-	{ 96000, LC_540M, 1024, 11250 },
-	{ 128000, LC_540M, 4096, 33750 },
-	{ 176400, LC_540M, 3136, 18750 },
-	{ 192000, LC_540M, 2048, 11250 },
-	{ 32000, LC_810M, 1024, 50625 },
-	{ 44100, LC_810M, 784, 28125 },
-	{ 48000, LC_810M, 512, 16875 },
-	{ 64000, LC_810M, 2048, 50625 },
-	{ 88200, LC_810M, 1568, 28125 },
-	{ 96000, LC_810M, 1024, 16875 },
-	{ 128000, LC_810M, 4096, 50625 },
-	{ 176400, LC_810M, 3136, 28125 },
-	{ 192000, LC_810M, 2048, 16875 },
-};
-
-static const struct dp_aud_n_m *
-audio_config_dp_get_n_m(const struct intel_crtc_state *crtc_state, int rate)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(dp_aud_n_m); i++) {
-		if (rate == dp_aud_n_m[i].sample_rate &&
-		    crtc_state->port_clock == dp_aud_n_m[i].clock)
-			return &dp_aud_n_m[i];
-	}
-
-	return NULL;
-}
-
 static const struct {
 	int clock;
 	u32 config;
@@ -387,47 +320,17 @@ hsw_dp_audio_config_update(struct intel_encoder *encoder,
 			   const struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
-	struct i915_audio_component *acomp = i915->display.audio.component;
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
-	enum port port = encoder->port;
-	const struct dp_aud_n_m *nm;
-	int rate;
-	u32 tmp;
-
-	rate = acomp ? acomp->aud_sample_rate[port] : 0;
-	nm = audio_config_dp_get_n_m(crtc_state, rate);
-	if (nm)
-		drm_dbg_kms(&i915->drm, "using Maud %u, Naud %u\n", nm->m,
-			    nm->n);
-	else
-		drm_dbg_kms(&i915->drm, "using automatic Maud, Naud\n");
-
-	tmp = intel_de_read(i915, HSW_AUD_CFG(cpu_transcoder));
-	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
-	tmp &= ~AUD_CONFIG_PIXEL_CLOCK_HDMI_MASK;
-	tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
-	tmp |= AUD_CONFIG_N_VALUE_INDEX;
 
-	if (nm) {
-		tmp &= ~AUD_CONFIG_N_MASK;
-		tmp |= AUD_CONFIG_N(nm->n);
-		tmp |= AUD_CONFIG_N_PROG_ENABLE;
-	}
-
-	intel_de_write(i915, HSW_AUD_CFG(cpu_transcoder), tmp);
-
-	tmp = intel_de_read(i915, HSW_AUD_M_CTS_ENABLE(cpu_transcoder));
-	tmp &= ~AUD_CONFIG_M_MASK;
-	tmp &= ~AUD_M_CTS_M_VALUE_INDEX;
-	tmp &= ~AUD_M_CTS_M_PROG_ENABLE;
-
-	if (nm) {
-		tmp |= nm->m;
-		tmp |= AUD_M_CTS_M_VALUE_INDEX;
-		tmp |= AUD_M_CTS_M_PROG_ENABLE;
-	}
+	/* Enable time stamps. Let HW calculate Maud/Naud values */
+	intel_de_rmw(i915, HSW_AUD_CFG(cpu_transcoder),
+		     AUD_CONFIG_N_VALUE_INDEX |
+		     AUD_CONFIG_PIXEL_CLOCK_HDMI_MASK |
+		     AUD_CONFIG_UPPER_N_MASK |
+		     AUD_CONFIG_LOWER_N_MASK |
+		     AUD_CONFIG_N_PROG_ENABLE,
+		     AUD_CONFIG_N_VALUE_INDEX);
 
-	intel_de_write(i915, HSW_AUD_M_CTS_ENABLE(cpu_transcoder), tmp);
 }
 
 static void