dw_hdmi_qp_set_sample_rate() open-coded its own N and CTS lookup tables and search/compute helpers, but it lacked the out-of-table CTS fallback needed by strict HDMI sinks at TMDS rates not in the table. The original LG G3 OLED audio mute (linux-rockchip 070633) was caused by dw_hdmi_qp_find_cts() returning 0 at 185.625 MHz, leaving AUDPKT_ACR_CTS_OVR_EN clear and falling back to the controller's internal CTS auto-measurement, which produces incorrect timing on the wire at out-of-table rates.
The shared drm_hdmi_acr_get_n_cts() helper in drivers/gpu/drm/display/drm_hdmi_helper.c already implements the correct behaviour: it has the HDMI 1.4b spec N/CTS tables, and for TMDS rates not in the table it computes CTS = (TMDS * N) / (128 * Fs) inline (the canonical HDMI spec formula). It is already used by drivers/gpu/drm/msm/hdmi/hdmi_audio.c. Convert dw_hdmi_qp_set_sample_rate() to call the helper. This removes ~200 lines of open-coded tables and search functions (dw_hdmi_qp_find_n, _compute_n, _find_cts, _audio_math_diff, _match_tmds_n_table, common_tmds_n_table[], common_tmds_cts_table[]) and fixes the strict-sink audio mute as a side effect of using the helper's complete N+CTS path. Tested on R76S (RK3576) running Linux 7.0.1, against the LG G3 OLED (the sink that originally reported the mute in linux-rockchip 070633) at four TMDS rates spanning HDMI 1.4 and HDMI 2.0: TMDS Mode Audio with v3 148.5 MHz 1080p60 8-bit plays 185.625 MHz 1080p60 10-bit plays 297 MHz 1080p100 8-bit plays 594 MHz 3840p60 8-bit plays Without this change, the LG G3 mutes audio at 185.625, 297, and 594 MHz (every rate outside dw-hdmi-qp's open-coded CTS table, which contained only 148.5 MHz and below). With this change, drm_hdmi_acr_get_n_cts() supplies the correct CTS at every rate -- table-canonical at 148.5 / 297 / 594 MHz, and computed via the HDMI 1.4b formula at 185.625 MHz. The 148.5 MHz row is a regression check confirming the in-table path is unchanged. The Kogan KALED43XU9210STA (a permissive HDMI 2.0 sink that plays audio at all rates with or without this change) was used as a no-regression control: audio plays at 594 MHz with v3 loaded. The open-coded N table in dw-hdmi-qp included optimised N values for some TMDS rates that are not in the helper's table (e.g. various non-CEA rates between 28-162 MHz). For those rates the helper's fallback returns N = 128 * Fs / 1000, which is the same value dw_hdmi_qp_compute_n() returned when no table optimisation was needed; no audio regression has been observed at the rates tested above. Reported-by: Simon Wright <[email protected]> Closes: https://lore.kernel.org/linux-rockchip/me3p282mb21960d9d68bff520316bdfcea8...@me3p282mb2196.ausp282.prod.outlook.com/ Suggested-by: Cristian Ciocaltea <[email protected]> Suggested-by: Jonas Karlman <[email protected]> Tested-by: Simon Wright <[email protected]> Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Simon Wright <[email protected]> --- Changes in v3: - Switch to drm_hdmi_acr_get_n_cts() helper as suggested by Jonas Karlman, instead of adding the cts-from-N fallback inline. Removes ~200 lines of open-coded N/CTS tables and search code, and brings dw-hdmi-qp in line with msm/hdmi. - Re-tested on the LG G3 OLED (the sink that originally reported the mute) at all four TMDS rates (148.5 / 185.625 / 297 / 594 MHz); audio plays at every rate. v3 has not been re-tested on the LG C4 OLED or TCL 75P7K QLED that v2 included; those sinks are expected to behave the same as G3 since the helper returns spec-canonical HDMI 1.4b values. - Also addresses a do_div() divisor-type style issue flagged by sashiko's automated review of v2 (the offending line is removed by the helper switch). - Add Suggested-by: Jonas Karlman. - Rebased onto current drm-misc-next. Changes in v2: - Resend after v1 was mailer-mangled and unapplyable (reported by Luca Ceresoli). - Body split into shorter paragraphs for readability per Luca's review. - Original LG G3 report (linux-rockchip 070633) moved from inline prose to a Closes: trailer paired with Reported-by:, per Documentation/process/submitting-patches.rst. - Add Assisted-by: trailer per Documentation/process/coding-assistants.rst. v2: https://lore.kernel.org/linux-rockchip/[email protected]/ v1: https://lore.kernel.org/linux-rockchip/[email protected]/ drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 209 +------------------ 1 file changed, 1 insertion(+), 208 deletions(-) diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c index 0dbb1274360..4e745e2c97b 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c @@ -42,88 +42,6 @@ #define SCRAMB_POLL_DELAY_MS 3000 -/* - * Unless otherwise noted, entries in this table are 100% optimization. - * Values can be obtained from dw_hdmi_qp_compute_n() but that function is - * slow so we pre-compute values we expect to see. - * - * The values for TMDS 25175, 25200, 27000, 54000, 74250 and 148500 kHz are - * the recommended N values specified in the Audio chapter of the HDMI - * specification. - */ -static const struct dw_hdmi_audio_tmds_n { - unsigned long tmds; - unsigned int n_32k; - unsigned int n_44k1; - unsigned int n_48k; -} common_tmds_n_table[] = { - { .tmds = 25175000, .n_32k = 4576, .n_44k1 = 7007, .n_48k = 6864, }, - { .tmds = 25200000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 27000000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 28320000, .n_32k = 4096, .n_44k1 = 5586, .n_48k = 6144, }, - { .tmds = 30240000, .n_32k = 4096, .n_44k1 = 5642, .n_48k = 6144, }, - { .tmds = 31500000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, }, - { .tmds = 32000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, }, - { .tmds = 33750000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 36000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, - { .tmds = 40000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, }, - { .tmds = 49500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, - { .tmds = 50000000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, }, - { .tmds = 54000000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 65000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, - { .tmds = 68250000, .n_32k = 4096, .n_44k1 = 5376, .n_48k = 6144, }, - { .tmds = 71000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, - { .tmds = 72000000, .n_32k = 4096, .n_44k1 = 5635, .n_48k = 6144, }, - { .tmds = 73250000, .n_32k = 11648, .n_44k1 = 14112, .n_48k = 6144, }, - { .tmds = 74250000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 75000000, .n_32k = 4096, .n_44k1 = 5880, .n_48k = 6144, }, - { .tmds = 78750000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, }, - { .tmds = 78800000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, }, - { .tmds = 79500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, }, - { .tmds = 83500000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, - { .tmds = 85500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, - { .tmds = 88750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, }, - { .tmds = 97750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, }, - { .tmds = 101000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, - { .tmds = 106500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, }, - { .tmds = 108000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, - { .tmds = 115500000, .n_32k = 4096, .n_44k1 = 5712, .n_48k = 6144, }, - { .tmds = 119000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, }, - { .tmds = 135000000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, - { .tmds = 146250000, .n_32k = 11648, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 148500000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, - { .tmds = 154000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, }, - { .tmds = 162000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, - - /* For 297 MHz+ HDMI spec have some other rule for setting N */ - { .tmds = 297000000, .n_32k = 3073, .n_44k1 = 4704, .n_48k = 5120, }, - { .tmds = 594000000, .n_32k = 3073, .n_44k1 = 9408, .n_48k = 10240,}, - - /* End of table */ - { .tmds = 0, .n_32k = 0, .n_44k1 = 0, .n_48k = 0, }, -}; - -/* - * These are the CTS values as recommended in the Audio chapter of the HDMI - * specification. - */ -static const struct dw_hdmi_audio_tmds_cts { - unsigned long tmds; - unsigned int cts_32k; - unsigned int cts_44k1; - unsigned int cts_48k; -} common_tmds_cts_table[] = { - { .tmds = 25175000, .cts_32k = 28125, .cts_44k1 = 31250, .cts_48k = 28125, }, - { .tmds = 25200000, .cts_32k = 25200, .cts_44k1 = 28000, .cts_48k = 25200, }, - { .tmds = 27000000, .cts_32k = 27000, .cts_44k1 = 30000, .cts_48k = 27000, }, - { .tmds = 54000000, .cts_32k = 54000, .cts_44k1 = 60000, .cts_48k = 54000, }, - { .tmds = 74250000, .cts_32k = 74250, .cts_44k1 = 82500, .cts_48k = 74250, }, - { .tmds = 148500000, .cts_32k = 148500, .cts_44k1 = 165000, .cts_48k = 148500, }, - - /* End of table */ - { .tmds = 0, .cts_32k = 0, .cts_44k1 = 0, .cts_48k = 0, }, -}; - struct dw_hdmi_qp_i2c { struct i2c_adapter adap; @@ -215,130 +133,6 @@ static void dw_hdmi_qp_set_cts_n(struct dw_hdmi_qp *hdmi, unsigned int cts, AUDPKT_ACR_CONTROL1); } -static int dw_hdmi_qp_match_tmds_n_table(struct dw_hdmi_qp *hdmi, - unsigned long pixel_clk, - unsigned long freq) -{ - const struct dw_hdmi_audio_tmds_n *tmds_n = NULL; - int i; - - for (i = 0; common_tmds_n_table[i].tmds != 0; i++) { - if (pixel_clk == common_tmds_n_table[i].tmds) { - tmds_n = &common_tmds_n_table[i]; - break; - } - } - - if (!tmds_n) - return -ENOENT; - - switch (freq) { - case 32000: - return tmds_n->n_32k; - case 44100: - case 88200: - case 176400: - return (freq / 44100) * tmds_n->n_44k1; - case 48000: - case 96000: - case 192000: - return (freq / 48000) * tmds_n->n_48k; - default: - return -ENOENT; - } -} - -static u32 dw_hdmi_qp_audio_math_diff(unsigned int freq, unsigned int n, - unsigned int pixel_clk) -{ - u64 cts = mul_u32_u32(pixel_clk, n); - - return do_div(cts, 128 * freq); -} - -static unsigned int dw_hdmi_qp_compute_n(struct dw_hdmi_qp *hdmi, - unsigned long pixel_clk, - unsigned long freq) -{ - unsigned int min_n = DIV_ROUND_UP((128 * freq), 1500); - unsigned int max_n = (128 * freq) / 300; - unsigned int ideal_n = (128 * freq) / 1000; - unsigned int best_n_distance = ideal_n; - unsigned int best_n = 0; - u64 best_diff = U64_MAX; - int n; - - /* If the ideal N could satisfy the audio math, then just take it */ - if (dw_hdmi_qp_audio_math_diff(freq, ideal_n, pixel_clk) == 0) - return ideal_n; - - for (n = min_n; n <= max_n; n++) { - u64 diff = dw_hdmi_qp_audio_math_diff(freq, n, pixel_clk); - - if (diff < best_diff || - (diff == best_diff && abs(n - ideal_n) < best_n_distance)) { - best_n = n; - best_diff = diff; - best_n_distance = abs(best_n - ideal_n); - } - - /* - * The best N already satisfy the audio math, and also be - * the closest value to ideal N, so just cut the loop. - */ - if (best_diff == 0 && (abs(n - ideal_n) > best_n_distance)) - break; - } - - return best_n; -} - -static unsigned int dw_hdmi_qp_find_n(struct dw_hdmi_qp *hdmi, unsigned long pixel_clk, - unsigned long sample_rate) -{ - int n = dw_hdmi_qp_match_tmds_n_table(hdmi, pixel_clk, sample_rate); - - if (n > 0) - return n; - - dev_warn(hdmi->dev, "Rate %lu missing; compute N dynamically\n", - pixel_clk); - - return dw_hdmi_qp_compute_n(hdmi, pixel_clk, sample_rate); -} - -static unsigned int dw_hdmi_qp_find_cts(struct dw_hdmi_qp *hdmi, unsigned long pixel_clk, - unsigned long sample_rate) -{ - const struct dw_hdmi_audio_tmds_cts *tmds_cts = NULL; - int i; - - for (i = 0; common_tmds_cts_table[i].tmds != 0; i++) { - if (pixel_clk == common_tmds_cts_table[i].tmds) { - tmds_cts = &common_tmds_cts_table[i]; - break; - } - } - - if (!tmds_cts) - return 0; - - switch (sample_rate) { - case 32000: - return tmds_cts->cts_32k; - case 44100: - case 88200: - case 176400: - return tmds_cts->cts_44k1; - case 48000: - case 96000: - case 192000: - return tmds_cts->cts_48k; - default: - return -ENOENT; - } -} - static void dw_hdmi_qp_set_audio_interface(struct dw_hdmi_qp *hdmi, struct hdmi_codec_daifmt *fmt, struct hdmi_codec_params *hparms) @@ -458,8 +252,7 @@ static void dw_hdmi_qp_set_sample_rate(struct dw_hdmi_qp *hdmi, unsigned long lo { unsigned int n, cts; - n = dw_hdmi_qp_find_n(hdmi, tmds_char_rate, sample_rate); - cts = dw_hdmi_qp_find_cts(hdmi, tmds_char_rate, sample_rate); + drm_hdmi_acr_get_n_cts(tmds_char_rate, sample_rate, &n, &cts); dw_hdmi_qp_set_cts_n(hdmi, cts, n); } base-commit: a48bbcc7ac739e93562d6148c6fa504c2e9f22f8 -- 2.53.0
