drm/radeon/kms: implement display watermark support for evergreen

Improper display watermarks can result in underflow to the display
controllers which can cause flickering or other artifacts.
This patch implements display watermark support and line buffer
allocation for evergreen asics.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/evergreen.c

@@ -284,9 +284,444 @@ void evergreen_hpd_fini(struct radeon_device *rdev)
 	}
 }
 
+/* watermark setup */
+
+static u32 evergreen_line_buffer_adjust(struct radeon_device *rdev,
+					struct radeon_crtc *radeon_crtc,
+					struct drm_display_mode *mode,
+					struct drm_display_mode *other_mode)
+{
+	u32 tmp = 0;
+	/*
+	 * Line Buffer Setup
+	 * There are 3 line buffers, each one shared by 2 display controllers.
+	 * DC_LB_MEMORY_SPLIT controls how that line buffer is shared between
+	 * the display controllers.  The paritioning is done via one of four
+	 * preset allocations specified in bits 2:0:
+	 * first display controller
+	 *  0 - first half of lb (3840 * 2)
+	 *  1 - first 3/4 of lb (5760 * 2)
+	 *  2 - whole lb (7680 * 2)
+	 *  3 - first 1/4 of lb (1920 * 2)
+	 * second display controller
+	 *  4 - second half of lb (3840 * 2)
+	 *  5 - second 3/4 of lb (5760 * 2)
+	 *  6 - whole lb (7680 * 2)
+	 *  7 - last 1/4 of lb (1920 * 2)
+	 */
+	if (mode && other_mode) {
+		if (mode->hdisplay > other_mode->hdisplay) {
+			if (mode->hdisplay > 2560)
+				tmp = 1; /* 3/4 */
+			else
+				tmp = 0; /* 1/2 */
+		} else if (other_mode->hdisplay > mode->hdisplay) {
+			if (other_mode->hdisplay > 2560)
+				tmp = 3; /* 1/4 */
+			else
+				tmp = 0; /* 1/2 */
+		} else
+			tmp = 0; /* 1/2 */
+	} else if (mode)
+		tmp = 2; /* whole */
+	else if (other_mode)
+		tmp = 3; /* 1/4 */
+
+	/* second controller of the pair uses second half of the lb */
+	if (radeon_crtc->crtc_id % 2)
+		tmp += 4;
+	WREG32(DC_LB_MEMORY_SPLIT + radeon_crtc->crtc_offset, tmp);
+
+	switch (tmp) {
+	case 0:
+	case 4:
+	default:
+		return 3840 * 2;
+	case 1:
+	case 5:
+		return 5760 * 2;
+	case 2:
+	case 6:
+		return 7680 * 2;
+	case 3:
+	case 7:
+		return 1920 * 2;
+	}
+}
+
+static u32 evergreen_get_number_of_dram_channels(struct radeon_device *rdev)
+{
+	u32 tmp = RREG32(MC_SHARED_CHMAP);
+
+	switch ((tmp & NOOFCHAN_MASK) >> NOOFCHAN_SHIFT) {
+	case 0:
+	default:
+		return 1;
+	case 1:
+		return 2;
+	case 2:
+		return 4;
+	case 3:
+		return 8;
+	}
+}
+
+struct evergreen_wm_params {
+	u32 dram_channels; /* number of dram channels */
+	u32 yclk;          /* bandwidth per dram data pin in kHz */
+	u32 sclk;          /* engine clock in kHz */
+	u32 disp_clk;      /* display clock in kHz */
+	u32 src_width;     /* viewport width */
+	u32 active_time;   /* active display time in ns */
+	u32 blank_time;    /* blank time in ns */
+	bool interlaced;    /* mode is interlaced */
+	fixed20_12 vsc;    /* vertical scale ratio */
+	u32 num_heads;     /* number of active crtcs */
+	u32 bytes_per_pixel; /* bytes per pixel display + overlay */
+	u32 lb_size;       /* line buffer allocated to pipe */
+	u32 vtaps;         /* vertical scaler taps */
+};
+
+static u32 evergreen_dram_bandwidth(struct evergreen_wm_params *wm)
+{
+	/* Calculate DRAM Bandwidth and the part allocated to display. */
+	fixed20_12 dram_efficiency; /* 0.7 */
+	fixed20_12 yclk, dram_channels, bandwidth;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1000);
+	yclk.full = dfixed_const(wm->yclk);
+	yclk.full = dfixed_div(yclk, a);
+	dram_channels.full = dfixed_const(wm->dram_channels * 4);
+	a.full = dfixed_const(10);
+	dram_efficiency.full = dfixed_const(7);
+	dram_efficiency.full = dfixed_div(dram_efficiency, a);
+	bandwidth.full = dfixed_mul(dram_channels, yclk);
+	bandwidth.full = dfixed_mul(bandwidth, dram_efficiency);
+
+	return dfixed_trunc(bandwidth);
+}
+
+static u32 evergreen_dram_bandwidth_for_display(struct evergreen_wm_params *wm)
+{
+	/* Calculate DRAM Bandwidth and the part allocated to display. */
+	fixed20_12 disp_dram_allocation; /* 0.3 to 0.7 */
+	fixed20_12 yclk, dram_channels, bandwidth;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1000);
+	yclk.full = dfixed_const(wm->yclk);
+	yclk.full = dfixed_div(yclk, a);
+	dram_channels.full = dfixed_const(wm->dram_channels * 4);
+	a.full = dfixed_const(10);
+	disp_dram_allocation.full = dfixed_const(3); /* XXX worse case value 0.3 */
+	disp_dram_allocation.full = dfixed_div(disp_dram_allocation, a);
+	bandwidth.full = dfixed_mul(dram_channels, yclk);
+	bandwidth.full = dfixed_mul(bandwidth, disp_dram_allocation);
+
+	return dfixed_trunc(bandwidth);
+}
+
+static u32 evergreen_data_return_bandwidth(struct evergreen_wm_params *wm)
+{
+	/* Calculate the display Data return Bandwidth */
+	fixed20_12 return_efficiency; /* 0.8 */
+	fixed20_12 sclk, bandwidth;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1000);
+	sclk.full = dfixed_const(wm->sclk);
+	sclk.full = dfixed_div(sclk, a);
+	a.full = dfixed_const(10);
+	return_efficiency.full = dfixed_const(8);
+	return_efficiency.full = dfixed_div(return_efficiency, a);
+	a.full = dfixed_const(32);
+	bandwidth.full = dfixed_mul(a, sclk);
+	bandwidth.full = dfixed_mul(bandwidth, return_efficiency);
+
+	return dfixed_trunc(bandwidth);
+}
+
+static u32 evergreen_dmif_request_bandwidth(struct evergreen_wm_params *wm)
+{
+	/* Calculate the DMIF Request Bandwidth */
+	fixed20_12 disp_clk_request_efficiency; /* 0.8 */
+	fixed20_12 disp_clk, bandwidth;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1000);
+	disp_clk.full = dfixed_const(wm->disp_clk);
+	disp_clk.full = dfixed_div(disp_clk, a);
+	a.full = dfixed_const(10);
+	disp_clk_request_efficiency.full = dfixed_const(8);
+	disp_clk_request_efficiency.full = dfixed_div(disp_clk_request_efficiency, a);
+	a.full = dfixed_const(32);
+	bandwidth.full = dfixed_mul(a, disp_clk);
+	bandwidth.full = dfixed_mul(bandwidth, disp_clk_request_efficiency);
+
+	return dfixed_trunc(bandwidth);
+}
+
+static u32 evergreen_available_bandwidth(struct evergreen_wm_params *wm)
+{
+	/* Calculate the Available bandwidth. Display can use this temporarily but not in average. */
+	u32 dram_bandwidth = evergreen_dram_bandwidth(wm);
+	u32 data_return_bandwidth = evergreen_data_return_bandwidth(wm);
+	u32 dmif_req_bandwidth = evergreen_dmif_request_bandwidth(wm);
+
+	return min(dram_bandwidth, min(data_return_bandwidth, dmif_req_bandwidth));
+}
+
+static u32 evergreen_average_bandwidth(struct evergreen_wm_params *wm)
+{
+	/* Calculate the display mode Average Bandwidth
+	 * DisplayMode should contain the source and destination dimensions,
+	 * timing, etc.
+	 */
+	fixed20_12 bpp;
+	fixed20_12 line_time;
+	fixed20_12 src_width;
+	fixed20_12 bandwidth;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1000);
+	line_time.full = dfixed_const(wm->active_time + wm->blank_time);
+	line_time.full = dfixed_div(line_time, a);
+	bpp.full = dfixed_const(wm->bytes_per_pixel);
+	src_width.full = dfixed_const(wm->src_width);
+	bandwidth.full = dfixed_mul(src_width, bpp);
+	bandwidth.full = dfixed_mul(bandwidth, wm->vsc);
+	bandwidth.full = dfixed_div(bandwidth, line_time);
+
+	return dfixed_trunc(bandwidth);
+}
+
+static u32 evergreen_latency_watermark(struct evergreen_wm_params *wm)
+{
+	/* First calcualte the latency in ns */
+	u32 mc_latency = 2000; /* 2000 ns. */
+	u32 available_bandwidth = evergreen_available_bandwidth(wm);
+	u32 worst_chunk_return_time = (512 * 8 * 1000) / available_bandwidth;
+	u32 cursor_line_pair_return_time = (128 * 4 * 1000) / available_bandwidth;
+	u32 dc_latency = 40000000 / wm->disp_clk; /* dc pipe latency */
+	u32 other_heads_data_return_time = ((wm->num_heads + 1) * worst_chunk_return_time) +
+		(wm->num_heads * cursor_line_pair_return_time);
+	u32 latency = mc_latency + other_heads_data_return_time + dc_latency;
+	u32 max_src_lines_per_dst_line, lb_fill_bw, line_fill_time;
+	fixed20_12 a, b, c;
+
+	if (wm->num_heads == 0)
+		return 0;
+
+	a.full = dfixed_const(2);
+	b.full = dfixed_const(1);
+	if ((wm->vsc.full > a.full) ||
+	    ((wm->vsc.full > b.full) && (wm->vtaps >= 3)) ||
+	    (wm->vtaps >= 5) ||
+	    ((wm->vsc.full >= a.full) && wm->interlaced))
+		max_src_lines_per_dst_line = 4;
+	else
+		max_src_lines_per_dst_line = 2;
+
+	a.full = dfixed_const(available_bandwidth);
+	b.full = dfixed_const(wm->num_heads);
+	a.full = dfixed_div(a, b);
+
+	b.full = dfixed_const(1000);
+	c.full = dfixed_const(wm->disp_clk);
+	b.full = dfixed_div(c, b);
+	c.full = dfixed_const(wm->bytes_per_pixel);
+	b.full = dfixed_mul(b, c);
+
+	lb_fill_bw = min(dfixed_trunc(a), dfixed_trunc(b));
+
+	a.full = dfixed_const(max_src_lines_per_dst_line * wm->src_width * wm->bytes_per_pixel);
+	b.full = dfixed_const(1000);
+	c.full = dfixed_const(lb_fill_bw);
+	b.full = dfixed_div(c, b);
+	a.full = dfixed_div(a, b);
+	line_fill_time = dfixed_trunc(a);
+
+	if (line_fill_time < wm->active_time)
+		return latency;
+	else
+		return latency + (line_fill_time - wm->active_time);
+
+}
+
+static bool evergreen_average_bandwidth_vs_dram_bandwidth_for_display(struct evergreen_wm_params *wm)
+{
+	if (evergreen_average_bandwidth(wm) <=
+	    (evergreen_dram_bandwidth_for_display(wm) / wm->num_heads))
+		return true;
+	else
+		return false;
+};
+
+static bool evergreen_average_bandwidth_vs_available_bandwidth(struct evergreen_wm_params *wm)
+{
+	if (evergreen_average_bandwidth(wm) <=
+	    (evergreen_available_bandwidth(wm) / wm->num_heads))
+		return true;
+	else
+		return false;
+};
+
+static bool evergreen_check_latency_hiding(struct evergreen_wm_params *wm)
+{
+	u32 lb_partitions = wm->lb_size / wm->src_width;
+	u32 line_time = wm->active_time + wm->blank_time;
+	u32 latency_tolerant_lines;
+	u32 latency_hiding;
+	fixed20_12 a;
+
+	a.full = dfixed_const(1);
+	if (wm->vsc.full > a.full)
+		latency_tolerant_lines = 1;
+	else {
+		if (lb_partitions <= (wm->vtaps + 1))
+			latency_tolerant_lines = 1;
+		else
+			latency_tolerant_lines = 2;
+	}
+
+	latency_hiding = (latency_tolerant_lines * line_time + wm->blank_time);
+
+	if (evergreen_latency_watermark(wm) <= latency_hiding)
+		return true;
+	else
+		return false;
+}
+
+static void evergreen_program_watermarks(struct radeon_device *rdev,
+					 struct radeon_crtc *radeon_crtc,
+					 u32 lb_size, u32 num_heads)
+{
+	struct drm_display_mode *mode = &radeon_crtc->base.mode;
+	struct evergreen_wm_params wm;
+	u32 pixel_period;
+	u32 line_time = 0;
+	u32 latency_watermark_a = 0, latency_watermark_b = 0;
+	u32 priority_a_mark = 0, priority_b_mark = 0;
+	u32 priority_a_cnt = PRIORITY_OFF;
+	u32 priority_b_cnt = PRIORITY_OFF;
+	u32 pipe_offset = radeon_crtc->crtc_id * 16;
+	u32 tmp, arb_control3;
+	fixed20_12 a, b, c;
+
+	if (radeon_crtc->base.enabled && num_heads && mode) {
+		pixel_period = 1000000 / (u32)mode->clock;
+		line_time = min((u32)mode->crtc_htotal * pixel_period, (u32)65535);
+		priority_a_cnt = 0;
+		priority_b_cnt = 0;
+
+		wm.yclk = rdev->pm.current_mclk * 10;
+		wm.sclk = rdev->pm.current_sclk * 10;
+		wm.disp_clk = mode->clock;
+		wm.src_width = mode->crtc_hdisplay;
+		wm.active_time = mode->crtc_hdisplay * pixel_period;
+		wm.blank_time = line_time - wm.active_time;
+		wm.interlaced = false;
+		if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+			wm.interlaced = true;
+		wm.vsc = radeon_crtc->vsc;
+		wm.vtaps = 1;
+		if (radeon_crtc->rmx_type != RMX_OFF)
+			wm.vtaps = 2;
+		wm.bytes_per_pixel = 4; /* XXX: get this from fb config */
+		wm.lb_size = lb_size;
+		wm.dram_channels = evergreen_get_number_of_dram_channels(rdev);
+		wm.num_heads = num_heads;
+
+		/* set for high clocks */
+		latency_watermark_a = min(evergreen_latency_watermark(&wm), (u32)65535);
+		/* set for low clocks */
+		/* wm.yclk = low clk; wm.sclk = low clk */
+		latency_watermark_b = min(evergreen_latency_watermark(&wm), (u32)65535);
+
+		/* possibly force display priority to high */
+		/* should really do this at mode validation time... */
+		if (!evergreen_average_bandwidth_vs_dram_bandwidth_for_display(&wm) ||
+		    !evergreen_average_bandwidth_vs_available_bandwidth(&wm) ||
+		    !evergreen_check_latency_hiding(&wm) ||
+		    (rdev->disp_priority == 2)) {
+			DRM_INFO("force priority to high\n");
+			priority_a_cnt |= PRIORITY_ALWAYS_ON;
+			priority_b_cnt |= PRIORITY_ALWAYS_ON;
+		}
+
+		a.full = dfixed_const(1000);
+		b.full = dfixed_const(mode->clock);
+		b.full = dfixed_div(b, a);
+		c.full = dfixed_const(latency_watermark_a);
+		c.full = dfixed_mul(c, b);
+		c.full = dfixed_mul(c, radeon_crtc->hsc);
+		c.full = dfixed_div(c, a);
+		a.full = dfixed_const(16);
+		c.full = dfixed_div(c, a);
+		priority_a_mark = dfixed_trunc(c);
+		priority_a_cnt |= priority_a_mark & PRIORITY_MARK_MASK;
+
+		a.full = dfixed_const(1000);
+		b.full = dfixed_const(mode->clock);
+		b.full = dfixed_div(b, a);
+		c.full = dfixed_const(latency_watermark_b);
+		c.full = dfixed_mul(c, b);
+		c.full = dfixed_mul(c, radeon_crtc->hsc);
+		c.full = dfixed_div(c, a);
+		a.full = dfixed_const(16);
+		c.full = dfixed_div(c, a);
+		priority_b_mark = dfixed_trunc(c);
+		priority_b_cnt |= priority_b_mark & PRIORITY_MARK_MASK;
+	}
+
+	/* select wm A */
+	arb_control3 = RREG32(PIPE0_ARBITRATION_CONTROL3 + pipe_offset);
+	tmp = arb_control3;
+	tmp &= ~LATENCY_WATERMARK_MASK(3);
+	tmp |= LATENCY_WATERMARK_MASK(1);
+	WREG32(PIPE0_ARBITRATION_CONTROL3 + pipe_offset, tmp);
+	WREG32(PIPE0_LATENCY_CONTROL + pipe_offset,
+	       (LATENCY_LOW_WATERMARK(latency_watermark_a) |
+		LATENCY_HIGH_WATERMARK(line_time)));
+	/* select wm B */
+	tmp = RREG32(PIPE0_ARBITRATION_CONTROL3 + pipe_offset);
+	tmp &= ~LATENCY_WATERMARK_MASK(3);
+	tmp |= LATENCY_WATERMARK_MASK(2);
+	WREG32(PIPE0_ARBITRATION_CONTROL3 + pipe_offset, tmp);
+	WREG32(PIPE0_LATENCY_CONTROL + pipe_offset,
+	       (LATENCY_LOW_WATERMARK(latency_watermark_b) |
+		LATENCY_HIGH_WATERMARK(line_time)));
+	/* restore original selection */
+	WREG32(PIPE0_ARBITRATION_CONTROL3 + pipe_offset, arb_control3);
+
+	/* write the priority marks */
+	WREG32(PRIORITY_A_CNT + radeon_crtc->crtc_offset, priority_a_cnt);
+	WREG32(PRIORITY_B_CNT + radeon_crtc->crtc_offset, priority_b_cnt);
+
+}
+
 void evergreen_bandwidth_update(struct radeon_device *rdev)
 {
-	/* XXX */
+	struct drm_display_mode *mode0 = NULL;
+	struct drm_display_mode *mode1 = NULL;
+	u32 num_heads = 0, lb_size;
+	int i;
+
+	radeon_update_display_priority(rdev);
+
+	for (i = 0; i < rdev->num_crtc; i++) {
+		if (rdev->mode_info.crtcs[i]->base.enabled)
+			num_heads++;
+	}
+	for (i = 0; i < rdev->num_crtc; i += 2) {
+		mode0 = &rdev->mode_info.crtcs[i]->base.mode;
+		mode1 = &rdev->mode_info.crtcs[i+1]->base.mode;
+		lb_size = evergreen_line_buffer_adjust(rdev, rdev->mode_info.crtcs[i], mode0, mode1);
+		evergreen_program_watermarks(rdev, rdev->mode_info.crtcs[i], lb_size, num_heads);
+		lb_size = evergreen_line_buffer_adjust(rdev, rdev->mode_info.crtcs[i+1], mode1, mode0);
+		evergreen_program_watermarks(rdev, rdev->mode_info.crtcs[i+1], lb_size, num_heads);
+	}
 }
 
 static int evergreen_mc_wait_for_idle(struct radeon_device *rdev)

drivers/gpu/drm/radeon/evergreend.h

@@ -412,6 +412,19 @@
 #define		SOFT_RESET_REGBB		       	(1 << 22)
 #define		SOFT_RESET_ORB				(1 << 23)
 
+/* display watermarks */
+#define	DC_LB_MEMORY_SPLIT				  0x6b0c
+#define	PRIORITY_A_CNT			                  0x6b18
+#define		PRIORITY_MARK_MASK			  0x7fff
+#define		PRIORITY_OFF				  (1 << 16)
+#define		PRIORITY_ALWAYS_ON			  (1 << 20)
+#define	PRIORITY_B_CNT			                  0x6b1c
+#define	PIPE0_ARBITRATION_CONTROL3			  0x0bf0
+#       define LATENCY_WATERMARK_MASK(x)                  ((x) << 16)
+#define	PIPE0_LATENCY_CONTROL			          0x0bf4
+#       define LATENCY_LOW_WATERMARK(x)                   ((x) << 0)
+#       define LATENCY_HIGH_WATERMARK(x)                  ((x) << 16)
+
 #define IH_RB_CNTL                                        0x3e00
 #       define IH_RB_ENABLE                               (1 << 0)
 #       define IH_IB_SIZE(x)                              ((x) << 1) /* log2 */