[Intel-gfx] [RFC 2/5] drm/hdmi21: Add non dsc frl capacity computation helpers
Vandita Kulkarni
vandita.kulkarni at intel.com
Thu Feb 3 05:50:09 UTC 2022
Add helper functions for computing non dsc frl
link characteristics
Signed-off-by: Vandita Kulkarni <vandita.kulkarni at intel.com>
---
drivers/gpu/drm/drm_frl_dfm_helper.c | 396 +++++++++++++++++++++++++++
1 file changed, 396 insertions(+)
create mode 100644 drivers/gpu/drm/drm_frl_dfm_helper.c
diff --git a/drivers/gpu/drm/drm_frl_dfm_helper.c b/drivers/gpu/drm/drm_frl_dfm_helper.c
new file mode 100644
index 000000000000..8498083adf72
--- /dev/null
+++ b/drivers/gpu/drm/drm_frl_dfm_helper.c
@@ -0,0 +1,396 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2022 Intel Corp
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <drm/drm_frl_dfm_helper.h>
+#include <drm/drm_connector.h>
+
+/* Total frl charecters per super block */
+static u32 drm_get_frl_char_per_super_blk(u32 lanes)
+{
+ u32 frl_char_per_sb;
+
+ frl_char_per_sb = (4 * FRL_CHAR_PER_CHAR_BLK) + lanes;
+ return frl_char_per_sb;
+}
+
+/*
+ * Determine the overhead due to the inclusion of
+ * the SR and SSB FRL charecters used for
+ * super block framing
+ */
+static u32 drm_get_overhead_super_blk(u32 lanes)
+{
+ return (lanes * EFFICIENCY_MULTIPLIER) / drm_get_frl_char_per_super_blk(lanes);
+}
+
+/*
+ * Determine the overhead due to the inclusion of RS FEC pairity
+ * symbols. Each charecter block uses 8 FRL charecters for RS Pairity
+ * and there are 4 charecter blocks per super block
+ */
+static u32 drm_get_overhead_rs(u32 lanes)
+{
+ return (8 * 4 * EFFICIENCY_MULTIPLIER) / drm_get_frl_char_per_super_blk(lanes);
+}
+
+/* Determine the overhead due to FRL Map charecters.
+ * In a bandwidth constrained application, the FRL packets will be long,
+ * there will typically be two FRL Map Charecters per Super Block most of the time.
+ * When a tracnsition occurs between Hactive and Hblank (uncomperssed video) or
+ * HCactive and HCblank (compressed video transport), there may be a
+ * third FRL Map Charected. Therefore this spec assumes 2.5 FRL Map Charecters
+ * per Super Block.
+ */
+static u32 drm_get_overhead_frl_map_char(u32 lanes)
+{
+ return (25 * EFFICIENCY_MULTIPLIER) / (10 * drm_get_frl_char_per_super_blk(lanes));
+}
+
+/* Total minimum overhead multiplied by EFFICIENCY_MULIPLIER */
+static u32 drm_get_total_minimum_overhead(u32 lanes)
+{
+ u32 total_overhead_min;
+ u32 overhead_sb = drm_get_overhead_super_blk(lanes);
+ u32 overhead_rs = drm_get_overhead_rs(lanes);
+ u32 overhead_map = drm_get_overhead_frl_map_char(lanes);
+
+ total_overhead_min = overhead_sb + overhead_rs + overhead_map;
+
+ return total_overhead_min;
+}
+
+/*
+ * Additional margin to the overhead is provided to account for the possibility
+ * of more Map Charecters, zero padding at the end of HCactive, and other minor
+ * items
+ */
+static u32 drm_get_max_overhead(u32 total_overhead_min)
+{
+ u32 total_overhead_max;
+
+ total_overhead_max = total_overhead_min + OVERHEAD_M;
+ return total_overhead_max;
+}
+
+/* Collect the link charecteristics */
+
+/* Determine the maximum legal pixel rate */
+static u32 drm_get_max_legal_pixel_rate(u32 fpixel_clock_nominal_k)
+{
+ u32 fpixel_clock_max_k = (fpixel_clock_nominal_k *
+ (1000 + TOLERANCE_PIXEL_CLOCK)) / 1000;
+ return fpixel_clock_max_k;
+}
+
+/* Determine the minimum Video Line period */
+static u32 drm_get_min_video_line_period(u32 hactive, u32 hblank,
+ u32 fpixel_clock_max_k)
+{
+ u32 line_time_ns;
+
+ line_time_ns = ((hactive + hblank) * FRL_TIMING_NS_MULTIPLIER) /
+ fpixel_clock_max_k;
+ return line_time_ns;
+}
+
+/* Determine the worst-case slow FRL Bit Rate in kbps*/
+static u32 drm_get_min_frl_bit_rate(u32 frl_bit_rate_nominal_k)
+{
+ u32 frl_bit_rate_min_k;
+
+ frl_bit_rate_min_k = (frl_bit_rate_nominal_k / 1000000) *
+ (1000000 - TOLERANCE_FRL_BIT_RATE);
+ return frl_bit_rate_min_k;
+}
+
+/* Determine the worst-case slow FRL Charecter Rate */
+static u32 drm_get_min_frl_char_rate(u32 frl_bit_rate_min_k)
+{
+ u32 frl_char_rate_min_k;
+
+ frl_char_rate_min_k = frl_bit_rate_min_k / 18;
+ return frl_char_rate_min_k;
+}
+
+/* Determine the Minimum Total FRL charecters per line period */
+static u32
+drm_get_total_frl_char_per_line_period(u32 line_time_ns, u32 frl_char_rate_min_k,
+ u32 lanes)
+{
+ u32 frl_char_per_line_period;
+
+ frl_char_per_line_period = (line_time_ns * frl_char_rate_min_k * lanes *
+ 1000) / FRL_TIMING_NS_MULTIPLIER;
+ return frl_char_per_line_period;
+}
+
+/* Audio Support Verification Computations */
+
+/*
+ * Determine Audio Related Packet Rate considering the audio clock
+ * increased to maximim rate permitted by Tolerance Audio clock
+ */
+static u32
+drm_get_audio_pkt_rate(u32 f_audio, u32 num_audio_pkt)
+{
+ u32 audio_pkt_rate;
+
+ audio_pkt_rate = ((f_audio * num_audio_pkt + (2 * ACR_RATE_MAX)) *
+ (1000000 + TOLERANCE_AUDIO_CLOCK)) / 1000000;
+ return audio_pkt_rate;
+}
+
+/*
+ * Average required packets per line is
+ * Number of audio packets needed during Hblank
+ */
+static u32
+drm_get_audio_pkts_hblank(u32 audio_pkt_rate, u32 line_time_ns)
+{
+ u32 avg_audio_pkts_per_line;
+
+ avg_audio_pkts_per_line = DIV_ROUND_UP(audio_pkt_rate * line_time_ns,
+ FRL_TIMING_NS_MULTIPLIER);
+ return avg_audio_pkts_per_line;
+}
+
+/*
+ * Minimum required Hblank assuming no Control Period RC Compression
+ * This includes Video Guard band, Two Island Guard bands, two 12 character
+ * Control Periods and 32 * AudioPackets_Line.
+ * In addition, 32 character periods are allocated for the transmission of an
+ * ACR packet
+ */
+static u32
+drm_get_audio_hblank_min(u32 audio_pkts_line)
+{
+ u32 hblank_audio_min;
+
+ hblank_audio_min = 32 + 32 * audio_pkts_line;
+ return hblank_audio_min;
+}
+
+/*
+ * During the Hblank period, Audio packets (32 frl characters each),
+ * ACR packets (32 frl characters each), Island guard band (4 total frl characters)
+ * and Video guard band (3 frl characters) do not benefit from RC compression
+ * Therefore start by determining the number of Control Characters that maybe
+ * RC compressible
+ */
+static u32
+drm_get_num_char_rc_compressible(u32 color_format,
+ u32 bpc, u32 audio_packets_line, u32 hblank)
+{
+ u32 cfrl_free;
+ u32 kcd, k420;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR420)
+ k420 = 2;
+ else
+ k420 = 1;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR422)
+ kcd = 1;
+ else
+ kcd = bpc/8;
+
+ cfrl_free = max(((hblank * kcd) / k420 - 32 * audio_packets_line - 7),
+ U32_MIN);
+ return cfrl_free;
+}
+
+/*
+ * Determine the actual number of characters made available by
+ * RC compression
+ */
+static u32
+drm_get_num_char_compression_savings(u32 cfrl_free)
+{
+ /*In order to be conservative, situations are considered where
+ * maximum RC compression may not be possible.
+ * Add one character each for RC break caused by:
+ * • Island Preamble not aligned to the RC Compression
+ * • Video Preamble not aligned to the RC Compression
+ * • HSYNC lead edge not aligned to the RC Compression
+ * • HSYNC trail edge not aligned to the RC Compression
+ */
+ const u32 cfrl_margin = 4;
+ u32 cfrl_savings = max(((7 * cfrl_free) / 8) - cfrl_margin, U32_MIN);
+ return cfrl_savings;
+}
+
+static u32
+drm_get_frl_bits_per_pixel(u32 color_format, u32 bpc)
+{
+ u32 kcd, k420, bpp;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR420)
+ k420 = 2;
+ else
+ k420 = 1;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR422)
+ kcd = 1;
+ else
+ kcd = bpc / 8;
+
+ bpp = (24 * kcd) / k420;
+ return bpp;
+}
+
+static u32
+drm_get_video_bytes_per_line(u32 bpp, u32 hactive)
+{
+ u32 bytes_per_line;
+
+ bytes_per_line = (bpp * hactive) / 8;
+ return bytes_per_line;
+}
+
+/*
+ * Determine the required number of tribytes to carry active video
+ * per line
+ */
+static u32
+drm_get_active_video_tribytes_reqd(u32 bytes_per_line)
+{
+ u32 tribyte_active;
+
+ tribyte_active = DIV_ROUND_UP(bytes_per_line, 3);
+ return tribyte_active;
+}
+
+/* Determine the total available tribytes during the blanking period */
+static u32
+drm_get_blanking_tribytes_avail(u32 color_format,
+ u32 hblank, u32 bpc)
+{
+ u32 tribytes_blank;
+ u32 kcd, k420;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR420)
+ k420 = 2;
+ else
+ k420 = 1;
+
+ if (color_format == DRM_COLOR_FORMAT_YCBCR422)
+ kcd = 1;
+ else
+ kcd = bpc / 8;
+
+ tribytes_blank = (hblank * kcd) / k420;
+ return tribytes_blank;
+}
+
+/* Determine the average tribyte rate in kilo tribytes per sec */
+static u32
+drm_get_avg_tribyte_rate(u32 pixel_clk_max_khz, u32 tb_active, u32 tb_blank,
+ u32 hactive, u32 hblank)
+{
+ u32 ftb_avg_k;
+
+ ftb_avg_k = (pixel_clk_max_khz * (tb_active + tb_blank)) / (hactive + hblank);
+ return ftb_avg_k;
+}
+
+/*
+ * Determine the time required to transmit the active portion of the
+ * minimum possible active line period in the base timing
+ */
+static u32
+drm_get_tactive_ref(u32 line_time_ns, u32 hblank, u32 hactive)
+{
+ u32 tactive_ref_ns;
+
+ tactive_ref_ns = (line_time_ns * hactive) / (hblank + hactive);
+ return tactive_ref_ns;
+}
+
+/*
+ * Determine the time required to transmit the Video blanking portion
+ * of the minimum possible active line period in the base timing
+ */
+static u32
+drm_get_tblank_ref(u32 line_time_ns, u32 hblank, u32 hactive)
+{
+ u32 tblank_ref_ns;
+
+ tblank_ref_ns = (line_time_ns * hactive) / (hblank + hactive);
+ return tblank_ref_ns;
+}
+
+/*
+ * Determine the minimum time necessary to transmit the active tribytes
+ * considering frl bandwidth limitation.
+ * Given the available bandwidth (i.e after overhead is considered),
+ * tactive_min represents the amount of time needed to transmit all the
+ * active data
+ */
+static u32
+drm_get_tactive_min(u32 num_lanes, u32 tribyte_active,
+ u32 overhead_max_k, u32 frl_char_min_rate_k)
+{
+ u32 tactive_min_ns, nr, dr;
+
+ nr = 3/2 * tribyte_active * FRL_TIMING_NS_MULTIPLIER;
+ dr = (num_lanes * frl_char_min_rate_k * 1000 *
+ (EFFICIENCY_MULTIPLIER - overhead_max_k)) / EFFICIENCY_MULTIPLIER;
+ tactive_min_ns = nr / dr;
+
+ return tactive_min_ns;
+}
+
+/*
+ * Determine the minimum time necessary to transmit the video blanking
+ * tribytes considering frl bandwidth limitations
+ */
+static u32
+drm_get_tblank_min(u32 num_lanes, u32 tribyte_blank,
+ u32 overhead_max_k, u32 frl_char_min_rate_k)
+{
+ u32 tblank_min_ns, nr, dr;
+
+ nr = tribyte_blank * FRL_TIMING_NS_MULTIPLIER;
+ dr = (num_lanes * frl_char_min_rate_k * 1000 *
+ (EFFICIENCY_MULTIPLIER - overhead_max_k)) / EFFICIENCY_MULTIPLIER;
+ tblank_min_ns = nr / dr;
+ return tblank_min_ns;
+}
+
+/* Determine the disparity in tribytes */
+static u32
+drm_get_tribytes_borrowed(u32 tborrowed_ns, u32 ftb_avg_k)
+{
+ u32 tribytes_borrowed;
+
+ tribytes_borrowed = DIV_ROUND_UP((tborrowed_ns * ftb_avg_k * 1000),
+ FRL_TIMING_NS_MULTIPLIER);
+ return tribytes_borrowed;
+}
+
+/*
+ * Determine the actual number of payload FRL characters required to carry each
+ * video line
+ */
+static u32
+drm_get_frl_char_payload_actual(u32 tribytes_active, u32 tribytes_blank, u32 cfrl_savings)
+{
+ u32 frl_char_payload_actual;
+
+ frl_char_payload_actual = DIV_ROUND_UP(3 * tribytes_active, 2) + tribytes_blank - cfrl_savings;
+ return frl_char_payload_actual;
+}
+
+/* Determine the payload utilization of the total number of FRL characters */
+static u32
+drm_compute_payload_utilization(u32 frl_char_payload_actual, u32 frl_char_per_line_period)
+{
+ u32 utilization;
+
+ utilization = (frl_char_payload_actual * EFFICIENCY_MULTIPLIER) / frl_char_per_line_period;
+ return utilization;
+}
--
2.32.0
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