[PATCH v4] drm/i915: Update memory bandwidth formulae

[Radhakrishna Sripada]

The formulae has been updated to include more variables. Make
sure the code carries the same.

Bspec: 64631

v2: Make GEN11 follow the default route and fix calculation of
    maxdebw(RK)
v3: Fix div by zero on default case and Correct indent for fallthrough(Jani)
v4: Fix div by zero on gen11.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Suggested-by: Matt Roper <matthew.d.roper at intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
---
 drivers/gpu/drm/i915/display/intel_bw.c | 79 ++++++++++++++++++++-----
 1 file changed, 64 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
index 4b94256d7319..52bb7af9cd15 100644
--- a/drivers/gpu/drm/i915/display/intel_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_bw.c
@@ -27,6 +27,9 @@ struct intel_qgv_info {
 	u8 num_points;
 	u8 num_psf_points;
 	u8 t_bl;
+	u8 max_numchannels;
+	u8 channel_width;
+	u8 deinterleave;
 };
 
 static int dg1_mchbar_read_qgv_point_info(struct drm_i915_private *dev_priv,
@@ -133,7 +136,8 @@ int icl_pcode_restrict_qgv_points(struct drm_i915_private *dev_priv,
 }
 
 static int icl_get_qgv_points(struct drm_i915_private *dev_priv,
-			      struct intel_qgv_info *qi)
+			      struct intel_qgv_info *qi,
+			      bool is_y_tile)
 {
 	const struct dram_info *dram_info = &dev_priv->dram_info;
 	int i, ret;
@@ -144,17 +148,41 @@ static int icl_get_qgv_points(struct drm_i915_private *dev_priv,
 	if (DISPLAY_VER(dev_priv) == 12)
 		switch (dram_info->type) {
 		case INTEL_DRAM_DDR4:
-			qi->t_bl = 4;
+			qi->t_bl = is_y_tile ? 8 : 4;
+			qi->max_numchannels = 2;
+			qi->channel_width = 64;
+			qi->deinterleave = is_y_tile ? 1 : 2;
 			break;
 		case INTEL_DRAM_DDR5:
-			qi->t_bl = 8;
+			qi->t_bl = is_y_tile ? 16 : 8;
+			qi->max_numchannels = 4;
+			qi->channel_width = 32;
+			qi->deinterleave = is_y_tile ? 1 : 2;
+			break;
+		case INTEL_DRAM_LPDDR4:
+			if (IS_ROCKETLAKE(dev_priv)) {
+				qi->t_bl = 8;
+				qi->max_numchannels = 4;
+				qi->channel_width = 32;
+				qi->deinterleave = 2;
+				break;
+			}
+			fallthrough;
+		case INTEL_DRAM_LPDDR5:
+			qi->t_bl = 16;
+			qi->max_numchannels = 8;
+			qi->channel_width = 16;
+			qi->deinterleave = is_y_tile ? 2 : 4;
 			break;
 		default:
 			qi->t_bl = 16;
+			qi->max_numchannels = 1;
 			break;
 		}
-	else if (DISPLAY_VER(dev_priv) == 11)
+	else if (DISPLAY_VER(dev_priv) == 11) {
 		qi->t_bl = dev_priv->dram_info.type == INTEL_DRAM_DDR4 ? 4 : 8;
+		qi->max_numchannels = 1;
+	}
 
 	if (drm_WARN_ON(&dev_priv->drm,
 			qi->num_points > ARRAY_SIZE(qi->points)))
@@ -263,37 +291,58 @@ static const struct intel_sa_info adlp_sa_info = {
 static int icl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel_sa_info *sa)
 {
 	struct intel_qgv_info qi = {};
+	const struct dram_info *dram_info = &dev_priv->dram_info;
 	bool is_y_tile = true; /* assume y tile may be used */
 	int num_channels = max_t(u8, 1, dev_priv->dram_info.num_channels);
-	int deinterleave;
 	int ipqdepth, ipqdepthpch;
 	int dclk_max;
-	int maxdebw;
+	int maxdebw, peakbw;
+	int clperchgroup;
+	int num_groups = ARRAY_SIZE(dev_priv->max_bw);
 	int i, ret;
 
-	ret = icl_get_qgv_points(dev_priv, &qi);
+	ret = icl_get_qgv_points(dev_priv, &qi, is_y_tile);
 	if (ret) {
 		drm_dbg_kms(&dev_priv->drm,
 			    "Failed to get memory subsystem information, ignoring bandwidth limits");
 		return ret;
 	}
 
-	deinterleave = DIV_ROUND_UP(num_channels, is_y_tile ? 4 : 2);
-	dclk_max = icl_sagv_max_dclk(&qi);
+	if (dram_info->type == INTEL_DRAM_LPDDR4 || dram_info->type == INTEL_DRAM_LPDDR5)
+		num_channels *= 2;
+
+	if (qi.deinterleave == 0)
+		qi.deinterleave = DIV_ROUND_UP(num_channels, is_y_tile ? 4 : 2);
+
+	if (num_channels < qi.max_numchannels && DISPLAY_VER(dev_priv) >= 12)
+		qi.deinterleave = DIV_ROUND_UP(qi.deinterleave, 2);
+
+	num_channels = min_t(u8, num_channels, qi.max_numchannels);
+	dclk_max = icl_calc_bw(icl_sagv_max_dclk(&qi), 16, 1);
 
 	ipqdepthpch = 16;
 
-	maxdebw = min(sa->deprogbwlimit * 1000,
-		      icl_calc_bw(dclk_max, 16, 1) * 6 / 10); /* 60% */
+	peakbw = num_channels * DIV_ROUND_UP(qi.deinterleave, 8) * dclk_max;
+	maxdebw = min(sa->deprogbwlimit * 1000, peakbw * 6 / 10); /* 60% */
 	ipqdepth = min(ipqdepthpch, sa->displayrtids / num_channels);
+	/*
+	 * clperchgroup = 4kpagespermempage * clperchperblock,
+	 * clperchperblock = 8 / num_channels * interleave
+	 */
+	clperchgroup = 4 * DIV_ROUND_UP(8, num_channels) * qi.deinterleave;
 
-	for (i = 0; i < ARRAY_SIZE(dev_priv->max_bw); i++) {
+	for (i = 0; i < num_groups; i++) {
 		struct intel_bw_info *bi = &dev_priv->max_bw[i];
 		int clpchgroup;
 		int j;
 
-		clpchgroup = (sa->deburst * deinterleave / num_channels) << i;
-		bi->num_planes = (ipqdepth - clpchgroup) / clpchgroup + 1;
+		clpchgroup = (sa->deburst * qi.deinterleave / num_channels) << i;
+
+		if ((i < num_groups - 1 && clpchgroup < clperchgroup) ||
+		    DISPLAY_VER(dev_priv) == 11)
+			bi->num_planes = (ipqdepth - clpchgroup) / clpchgroup + 1;
+		else
+			bi->num_planes = 0;
 
 		bi->num_qgv_points = qi.num_points;
 		bi->num_psf_gv_points = qi.num_psf_points;
@@ -339,7 +388,7 @@ static int icl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel
 	 * SAGV point, but we can't send PCode commands to restrict it
 	 * as it will fail and pointless anyway.
 	 */
-	if (qi.num_points == 1)
+	if (qi.num_points >= 1)
 		dev_priv->sagv_status = I915_SAGV_NOT_CONTROLLED;
 	else
 		dev_priv->sagv_status = I915_SAGV_ENABLED;
-- 
2.20.1