drm/tidss: cleanup dma related settings

Clean up and improve DMA related settings. We didn't set many of the
relevant registers, like fifo_thresholds at all.

The specific values used are "sounds nice" guesses. We need to somehow
measure the DMA performance and improve these to cover most of the use
cases, but this patch should serve as a good starting point.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/tidss/tidss_dispc7.c

@@ -33,6 +33,8 @@
 #include "tidss_scale_coefs.h"
 #include "tidss_dispc7.h"
 
+static const char *dispc7_plane_name(struct dispc_device *dispc, u32 hw_plane);
+
 static const struct dispc7_features dispc7_am6_feats = {
 	.min_pclk = 1000,
 	.max_pclk = 200000000,
@@ -2398,13 +2400,9 @@ static bool dispc7_has_writeback(struct dispc_device *dispc)
 	return dispc->wb_managed;
 }
 
-static u32 dispc7_vid_get_fifo_size(struct dispc_device *dispc,
-				    u32 hw_plane)
+static u32 dispc7_vid_get_fifo_size(struct dispc_device *dispc, u32 hw_plane)
 {
-	const u32 unit_size = 16;	/* 128-bits */
-
-	return VID_REG_GET(dispc, hw_plane, DISPC_VID_BUF_SIZE_STATUS, 15, 0) *
-	       unit_size;
+	return VID_REG_GET(dispc, hw_plane, DISPC_VID_BUF_SIZE_STATUS, 15, 0);
 }
 
 static void dispc7_vid_set_mflag_threshold(struct dispc_device *dispc,
@@ -2414,31 +2412,16 @@ static void dispc7_vid_set_mflag_threshold(struct dispc_device *dispc,
 			 FLD_VAL(high, 31, 16) | FLD_VAL(low, 15, 0));
 }
 
-static void dispc7_vid_mflag_setup(struct dispc_device *dispc,
-				   u32 hw_plane)
+static void dispc7_vid_set_buf_threshold(struct dispc_device *dispc,
+					 u32 hw_plane, u32 low, u32 high)
 {
-	const u32 unit_size = 16;	/* 128-bits */
-	u32 size = dispc7_vid_get_fifo_size(dispc, hw_plane);
-	u32 low, high;
-
-	/*
-	 * Simulation team suggests below thesholds:
-	 * HT = fifosize * 5 / 8;
-	 * LT = fifosize * 4 / 8;
-	 */
-
-	low = size * 4 / 8 / unit_size;
-	high = size * 5 / 8 / unit_size;
-
-	dispc7_vid_set_mflag_threshold(dispc, hw_plane, low, high);
+	dispc7_vid_write(dispc, hw_plane, DISPC_VID_BUF_THRESHOLD,
+			 FLD_VAL(high, 31, 16) | FLD_VAL(low, 15, 0));
 }
 
 static u32 dispc7_wb_get_fifo_size(struct dispc_device *dispc)
 {
-	const u32 unit_size = 16;	/* 128-bits */
-
-	return WB_REG_GET(dispc, DISPC_VID_BUF_SIZE_STATUS, 15, 0) *
-	       unit_size;
+	return WB_REG_GET(dispc, DISPC_VID_BUF_SIZE_STATUS, 15, 0);
 }
 
 static void dispc7_wb_set_mflag_threshold(struct dispc_device *dispc,
@@ -2448,55 +2431,85 @@ static void dispc7_wb_set_mflag_threshold(struct dispc_device *dispc,
 			FLD_VAL(high, 31, 16) | FLD_VAL(low, 15, 0));
 }
 
-static void dispc7_wb_mflag_setup(struct dispc_device *dispc)
+static void dispc7_wb_set_buf_threshold(struct dispc_device *dispc,
+					 u32 low, u32 high)
 {
-	const u32 unit_size = 16;	/* 128-bits */
-	u32 size = dispc7_wb_get_fifo_size(dispc);
-	u32 low, high;
+	dispc7_wb_write(dispc, DISPC_WB_BUF_THRESHOLD,
+			FLD_VAL(high, 31, 16) | FLD_VAL(low, 15, 0));
+}
 
-	/*
-	 * Simulation team suggests below thesholds:
-	 * HT = fifosize * 5 / 8;
-	 * LT = fifosize * 4 / 8;
-	 */
+static void dispc7_plane_init(struct dispc_device *dispc)
+{
+	unsigned int hw_plane;
 
-	low = size * 4 / 8 / unit_size;
-	high = size * 5 / 8 / unit_size;
+	dev_dbg(dispc->dev, "%s()\n", __func__);
 
-	dispc7_wb_set_mflag_threshold(dispc, low, high);
-}
+	if (dispc->has_cfg_common) {
+		u32 cba_lo_pri = 1;
+		u32 cba_hi_pri = 0;
 
-static void dispc7_mflag_setup(struct dispc_device *dispc)
-{
-	unsigned int i;
+		CFG_REG_FLD_MOD(dispc, DSS_CBA_CFG, cba_lo_pri, 2, 0);
+		CFG_REG_FLD_MOD(dispc, DSS_CBA_CFG, cba_hi_pri, 5, 3);
 
-	if (!dispc->has_cfg_common)
-		goto no_cfg;
+		/* MFLAG_CTRL = ENABLED */
+		CFG_REG_FLD_MOD(dispc, DISPC_GLOBAL_MFLAG_ATTRIBUTE, 2, 1, 0);
+		/* MFLAG_START = MFLAGNORMALSTARTMODE */
+		CFG_REG_FLD_MOD(dispc, DISPC_GLOBAL_MFLAG_ATTRIBUTE, 0, 6, 6);
+	}
 
-	/* MFLAG_CTRL = ENABLED */
-	CFG_REG_FLD_MOD(dispc, DISPC_GLOBAL_MFLAG_ATTRIBUTE, 2, 1, 0);
-	/* MFLAG_START = MFLAGNORMALSTARTMODE */
-	CFG_REG_FLD_MOD(dispc, DISPC_GLOBAL_MFLAG_ATTRIBUTE, 0, 6, 6);
+	dispc_for_each_managed_plane(dispc, hw_plane) {
+		u32 size = dispc7_vid_get_fifo_size(dispc, hw_plane);
+		u32 thr_low, thr_high;
+		u32 mflag_low, mflag_high;
+		u32 preload;
 
-no_cfg:
-	dispc_for_each_managed_plane(dispc, i)
-		dispc7_vid_mflag_setup(dispc, i);
+		thr_high = size - 1;
+		thr_low = size / 2;
 
-	if (dispc7_has_writeback(dispc))
-		dispc7_wb_mflag_setup(dispc);
-}
+		mflag_high = size * 2 / 3;
+		mflag_low = size / 3;
 
-static void dispc7_plane_init(struct dispc_device *dispc)
-{
-	unsigned int i;
+		preload = thr_low;
 
-	dev_dbg(dispc->dev, "%s()\n", __func__);
+		dev_dbg(dispc->dev,
+			"%s: bufsize %u, buf_threshold %u/%u, mflag threshold %u/%u preload %u\n",
+			dispc7_plane_name(dispc, hw_plane),
+			size,
+			thr_high, thr_low,
+			mflag_high, mflag_low,
+			preload);
 
-	/* FIFO underflows when scaling if preload is not high enough */
-	dispc_for_each_managed_plane(dispc, i)
-		if (!dispc->feat->vid_lite[i])
-			VID_REG_FLD_MOD(dispc, i, DISPC_VID_PRELOAD,
-					0x7FF, 11, 0);
+		dispc7_vid_set_buf_threshold(dispc, hw_plane,
+					     thr_low, thr_high);
+		dispc7_vid_set_mflag_threshold(dispc, hw_plane,
+					       mflag_low, mflag_high);
+
+		dispc7_vid_write(dispc, hw_plane, DISPC_VID_PRELOAD, preload);
+
+		/* Prefech up to PRELOAD value */
+		VID_REG_FLD_MOD(dispc, hw_plane, DISPC_VID_ATTRIBUTES, 0, 19, 19);
+	}
+
+	if (dispc7_has_writeback(dispc)) {
+		u32 size = dispc7_wb_get_fifo_size(dispc);
+		u32 thr_low, thr_high;
+		u32 mflag_low, mflag_high;
+
+		thr_high = size - 1;
+		thr_low = size / 2;
+
+		mflag_high = size * 2 / 3;
+		mflag_low = size / 3;
+
+		dev_dbg(dispc->dev,
+			"wb: bufsize %u, buf_threshold %u/%u, mflag threshold %u/%u\n",
+			size,
+			thr_high, thr_low,
+			mflag_high, mflag_low);
+
+		dispc7_wb_set_buf_threshold(dispc, thr_low, thr_high);
+		dispc7_wb_set_mflag_threshold(dispc, mflag_low, mflag_high);
+	}
 }
 
 static void dispc7_vp_init(struct dispc_device *dispc)
@@ -2512,7 +2525,6 @@ static void dispc7_vp_init(struct dispc_device *dispc)
 
 static void dispc7_initial_config(struct dispc_device *dispc)
 {
-	dispc7_mflag_setup(dispc);
 	dispc7_plane_init(dispc);
 	dispc7_vp_init(dispc);