Ping.
On Wed, Feb 25, 2026 at 12:57:08PM -0500, Hamza Mahfooz wrote: > Video Format Data Blocks (VFDBs) contain the necessary information that > needs to be fed to the Optimized Video Timings (OVT) Algorithm. > Also, we require OVT support to cover modes that aren't supported by > earlier standards (e.g. CVT). So, parse all of the relevant VFDB data > and feed it to the OVT Algorithm, to extract all of the missing OVT > modes. > > Cc: Ian Forbes <[email protected]> > Cc: Jani Nikula <[email protected]> > Suggested-by: Karol Herbst <[email protected]> > Signed-off-by: Hamza Mahfooz <[email protected]> > --- > v3: move ovt stuff above add_cea_modes() and break up > calculate_ovt_mode() to make it easier to read. > > v4: fix 32 bit build and constify read-only vars. > > v5: implement suggestions from: > https://lore.kernel.org/dri-devel/[email protected]/ > and export drm_ovt_mode(). > > v6: rebased onto drm-misc-next and tested on an AYA AYANEO-OLED. > --- > drivers/gpu/drm/drm_edid.c | 465 +++++++++++++++++++++++++++++++++++++ > include/drm/drm_edid.h | 3 + > 2 files changed, 468 insertions(+) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 26bb7710a462..0e3141866f21 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -31,6 +31,7 @@ > #include <linux/bitfield.h> > #include <linux/byteorder/generic.h> > #include <linux/cec.h> > +#include <linux/gcd.h> > #include <linux/export.h> > #include <linux/hdmi.h> > #include <linux/i2c.h> > @@ -755,6 +756,87 @@ static const struct minimode extra_modes[] = { > { 2048, 1536, 60, 0 }, > }; > > +struct cta_rid { > + u16 hactive; > + u16 vactive; > + u8 hratio; > + u8 vratio; > +}; > + > +/* CTA-861-I Table 11 - Resolution Identification (RID) */ > +static const struct cta_rid rids[] = { > + [0] = { 0, 0, 0, 0 }, > + [1] = { 1280, 720, 16, 9 }, > + [2] = { 1280, 720, 64, 27 }, > + [3] = { 1680, 720, 64, 27 }, > + [4] = { 1920, 1080, 16, 9 }, > + [5] = { 1920, 1080, 64, 27 }, > + [6] = { 2560, 1080, 64, 27 }, > + [7] = { 3840, 1080, 32, 9 }, > + [8] = { 2560, 1440, 16, 9 }, > + [9] = { 3440, 1440, 64, 27 }, > + [10] = { 5120, 1440, 32, 9 }, > + [11] = { 3840, 2160, 16, 9 }, > + [12] = { 3840, 2160, 64, 27 }, > + [13] = { 5120, 2160, 64, 27 }, > + [14] = { 7680, 2160, 32, 9 }, > + [15] = { 5120, 2880, 16, 9 }, > + [16] = { 5120, 2880, 64, 27 }, > + [17] = { 6880, 2880, 64, 27 }, > + [18] = { 10240, 2880, 32, 9 }, > + [19] = { 7680, 4320, 16, 9 }, > + [20] = { 7680, 4320, 64, 27 }, > + [21] = { 10240, 4320, 64, 27 }, > + [22] = { 15360, 4320, 32, 9 }, > + [23] = { 11520, 6480, 16, 9 }, > + [24] = { 11520, 6480, 64, 27 }, > + [25] = { 15360, 6480, 64, 27 }, > + [26] = { 15360, 8640, 16, 9 }, > + [27] = { 15360, 8640, 64, 27 }, > + [28] = { 20480, 8640, 64, 27 }, > +}; > + > +/* CTA-861-I Table 12 - AVI InfoFrame Video Format Frame Rate */ > +static const u16 video_format_frame_rates[] = { > + /* Frame Rate 0-7 */ > + 0, 24, 25, 30, 48, 50, 60, 100, > + /* Frame Rate 8-15 */ > + 120, 144, 200, 240, 300, 360, 400, 480, > +}; > + > +/* CTA-861-I Table 13 - RID To VIC Mapping */ > +static const u8 rid_to_vic[][8] = { > + [0] = {}, > + [1] = { 60, 61, 62, 108, 19, 4, 41, 47 }, > + [2] = { 65, 66, 67, 109, 68, 69, 70, 71 }, > + [3] = { 79, 80, 81, 110, 82, 83, 84, 85 }, > + [4] = { 32, 33, 34, 111, 31, 16, 64, 63 }, > + [5] = { 72, 73, 74, 112, 75, 76, 77, 78 }, > + [6] = { 86, 87, 88, 113, 89, 90, 91, 92 }, > + [7] = {}, > + [8] = {}, > + [9] = {}, > + [10] = {}, > + [11] = { 93, 94, 95, 114, 96, 97, 117, 118 }, > + [12] = { 103, 104, 105, 116, 106, 107, 119, 120 }, > + [13] = { 121, 122, 123, 124, 125, 126, 127, 193 }, > + [14] = {}, > + [15] = {}, > + [16] = {}, > + [17] = {}, > + [18] = {}, > + [19] = { 194, 195, 196, 197, 198, 199, 200, 201 }, > + [20] = { 202, 203, 204, 205, 206, 207, 208, 209 }, > + [21] = { 210, 211, 212, 213, 214, 215, 216, 217 }, > + [22] = {}, > + [23] = {}, > + [24] = {}, > + [25] = {}, > + [26] = {}, > + [27] = {}, > + [28] = {}, > +}; > + > /* > * From CEA/CTA-861 spec. > * > @@ -4155,6 +4237,7 @@ static int add_detailed_modes(struct drm_connector > *connector, > #define CTA_DB_VIDEO 2 > #define CTA_DB_VENDOR 3 > #define CTA_DB_SPEAKER 4 > +#define CTA_DB_VIDEO_FORMAT 6 > #define CTA_DB_EXTENDED_TAG 7 > > /* CTA-861-H Table 62 - CTA Extended Tag Codes */ > @@ -4996,6 +5079,16 @@ struct cea_db { > u8 data[]; > } __packed; > > +struct cta_vfd { > + u8 rid; > + u8 fr_fact; > + bool bfr50; > + bool fr24; > + bool bfr60; > + bool fr144; > + bool fr48; > +}; > + > static int cea_db_tag(const struct cea_db *db) > { > return db->tag_length >> 5; > @@ -5274,6 +5367,376 @@ static int edid_hfeeodb_extension_block_count(const > struct edid *edid) > return cta[4 + 2]; > } > > +/* CTA-861 Video Format Descriptor (CTA VFD) */ > +static void parse_cta_vfd(struct cta_vfd *vfd, const u8 *data, int vfd_len) > +{ > + vfd->rid = data[0] & 0x3f; > + vfd->bfr50 = data[0] & 0x80; > + vfd->fr24 = data[0] & 0x40; > + vfd->bfr60 = vfd_len > 1 ? (data[1] & 0x80) : true; > + vfd->fr144 = vfd_len > 1 ? (data[1] & 0x40) : false; > + vfd->fr_fact = vfd_len > 1 ? (data[1] & 0x3f) : 0x3; > + vfd->fr48 = vfd_len > 2 ? (data[2] & 0x1) : false; > +} > + > +static bool vfd_has_fr(const struct cta_vfd *vfd, int rate) > +{ > + static const u8 factors[] = { > + 1, 2, 4, 8, 12, 16 > + }; > + int factor = 0; > + int i; > + > + switch (rate) { > + case 24: > + return vfd->fr24; > + case 48: > + return vfd->fr48; > + case 144: > + return vfd->fr144; > + } > + > + if (!(rate % 25)) { > + if (!vfd->bfr50) > + return false; > + > + factor = rate / 25; > + } else if (!(rate % 30)) { > + if (!vfd->bfr60) > + return false; > + > + factor = rate / 30; > + } > + > + for (i = 0; i < ARRAY_SIZE(factors); i++) > + if (factor == factors[i] && (vfd->fr_fact & (1 << i))) > + return true; > + > + return false; > +} > + > +#define OVT_PIXEL_CLOCK_GRANULARITY 1000 /* Hz */ > +#define OVT_MIN_HTOTAL_GRANULARITY 8 /* pixels */ > +#define OVT_MIN_VBLANK_DURATION 460000000 /* ps */ > +#define OVT_MIN_VBLANK_LINES 20 > +#define OVT_MIN_VSYNC_LEADING_EDGE 400 /* us */ > +#define OVT_MIN_VSYNC_LE_LINES 14 > +#define OVT_MIN_CLOCK_RATE_420 590000000 /* Hz */ > +#define OVT_PIXEL_FACTOR_420 2 > +#define OVT_MIN_HBLANK_444 80 /* pixels */ > +#define OVT_MIN_HBLANK_420 128 /* pixels */ > +#define OVT_MAX_CHUNK_RATE 650000000 /* Hz */ > +#define OVT_AUDIO_PACKET_RATE 195000 /* Hz */ > +#define OVT_AUDIO_PACKET_SIZE 32 > +#define OVT_LINE_OVERHEAD 32 > +#define OVT_HSYNC_WIDTH 32 > +#define OVT_VSYNC_WIDTH 8 > + > +static u32 calculate_ovt_min_vtotal(const struct cta_rid *rid, u64 max_vrate, > + u32 vtotal_granularity) > +{ > + u64 max_active_time; > + u32 min_line_time; > + u32 min_vblank; > + u32 min_vtotal; > + > + /* step 2 */ > + max_active_time = div64_u64(1000000000000, max_vrate) - > + (u64)OVT_MIN_VBLANK_DURATION; > + > + min_line_time = div_u64(max_active_time, rid->vactive); > + > + min_vblank = max_t(u64, (u64)OVT_MIN_VBLANK_LINES, > + DIV64_U64_ROUND_UP(OVT_MIN_VBLANK_DURATION, > + min_line_time)); > + > + min_vtotal = rid->vactive + min_vblank; > + > + if (min_vtotal % vtotal_granularity) > + min_vtotal += vtotal_granularity - (min_vtotal % > + vtotal_granularity); > + > + return min_vtotal; > +} > + > +static u32 calculate_ovt_min_htotal(const struct cta_rid *rid, > + const u32 max_vrate, > + const u32 min_vtotal, > + u32 *min_hblank, > + u32 *htotal_granularity) > +{ > + u32 max_audio_packets_per_line; > + u32 htotal_granularity_chunk; > + u64 min_pixel_clock_rate; > + u32 min_line_rate; > + u32 min_htotal; > + > + /* step 3 */ > + min_line_rate = max_vrate * min_vtotal; > + > + max_audio_packets_per_line = DIV_ROUND_UP(OVT_AUDIO_PACKET_RATE, > + min_line_rate); > + > + /* step 4 */ > + *min_hblank = OVT_LINE_OVERHEAD + OVT_AUDIO_PACKET_SIZE * > + max_audio_packets_per_line; > + > + min_htotal = rid->hactive + max(OVT_MIN_HBLANK_444, *min_hblank); > + > + min_pixel_clock_rate = max_vrate * min_htotal * min_vtotal; > + > + htotal_granularity_chunk = > + roundup_pow_of_two(DIV64_U64_ROUND_UP(min_pixel_clock_rate, > + OVT_MAX_CHUNK_RATE)); > + > + *htotal_granularity = max(OVT_MIN_HTOTAL_GRANULARITY, > + htotal_granularity_chunk); > + > + if (min_htotal % *htotal_granularity) > + min_htotal += *htotal_granularity - (min_htotal % > + *htotal_granularity); > + > + return min_htotal; > +} > + > +static u64 calculate_ovt_pixel_clock_rate(const struct cta_rid *rid, > + const u32 max_vrate, > + const u32 min_hblank, > + u32 min_htotal, > + u32 min_vtotal, > + const u32 htotal_granularity, > + const u32 vtotal_granularity, > + u32 *htotal, u32 *vtotal) > +{ > + u32 resolution_granularity; > + u64 pixel_clock_rate; > + u64 min_resolution; > + u64 rem; > + u32 h; > + u64 r; > + u32 v; > + > + resolution_granularity = OVT_PIXEL_CLOCK_GRANULARITY / > + gcd(OVT_PIXEL_CLOCK_GRANULARITY, max_vrate); > + > + do { > + /* step 5 */ > + min_resolution = 0; > + v = min_vtotal; > + > + goto loop_end; > + > + while (!min_resolution || r <= min_resolution) { > + goto inner_loop_end; > + > + while (rem || div64_u64(max_vrate * r, (h & ~(h - 1))) > > + OVT_MAX_CHUNK_RATE) { > + h += htotal_granularity; > + r = (u64)h * (u64)v; > +inner_loop_end: > + div64_u64_rem(r, resolution_granularity, &rem); > + } > + > + if (!min_resolution || r < min_resolution) { > + *htotal = h; > + *vtotal = v; > + min_resolution = r; > + } > + > + v += vtotal_granularity; > + > +loop_end: > + h = min_htotal; > + r = (u64)h * (u64)v; > + } > + > + pixel_clock_rate = max_vrate * min_resolution; > + > + /* step 6 */ > + min_htotal = rid->hactive + max(OVT_MIN_HBLANK_420, > + OVT_PIXEL_FACTOR_420 * > + min_hblank); > + > + } while (pixel_clock_rate >= OVT_MIN_CLOCK_RATE_420 && > + *htotal < min_htotal); > + > + return pixel_clock_rate; > +} > + > +static const struct cta_rid *find_rid(u8 rid) > +{ > + if (!rid || rid >= ARRAY_SIZE(rids)) > + return NULL; > + > + return &rids[rid]; > +} > + > +/* OVT Algorthim as specified in CTA-861-I */ > +struct drm_display_mode *drm_ovt_mode(struct drm_device *dev, int r_id, > + int vrefresh) > +{ > + const struct cta_rid *rid = find_rid(r_id); > + struct drm_display_mode *mode; > + u32 vtotal_granularity = 1; > + u32 htotal_granularity; > + u32 max_vrate = vrefresh; > + u64 pixel_clock_rate; > + u32 vsync_position; > + u32 min_hblank; > + u32 min_htotal; > + u32 min_vtotal; > + u32 htotal; > + u32 vtotal; > + > + if (!rid) > + return NULL; > + > + /* step 1 */ > + switch (vrefresh) { > + case 24: > + case 25: > + max_vrate = 30; > + fallthrough; > + case 30: > + vtotal_granularity = 20; > + break; > + case 48: > + case 50: > + max_vrate = 60; > + fallthrough; > + case 60: > + vtotal_granularity = 20; > + break; > + case 100: > + max_vrate = 120; > + fallthrough; > + case 120: > + vtotal_granularity = 5; > + break; > + case 200: > + max_vrate = 240; > + fallthrough; > + case 240: > + vtotal_granularity = 5; > + break; > + case 300: > + max_vrate = 360; > + fallthrough; > + case 360: > + vtotal_granularity = 5; > + break; > + case 400: > + max_vrate = 480; > + fallthrough; > + case 480: > + vtotal_granularity = 5; > + break; > + } > + > + min_vtotal = calculate_ovt_min_vtotal(rid, max_vrate, > + vtotal_granularity); > + > + min_htotal = calculate_ovt_min_htotal(rid, max_vrate, min_vtotal, > + &min_hblank, &htotal_granularity); > + > + pixel_clock_rate = calculate_ovt_pixel_clock_rate(rid, max_vrate, > + min_hblank, > + min_htotal, > + min_vtotal, > + htotal_granularity, > + vtotal_granularity, > + &htotal, &vtotal); > + > + /* step 7 */ > + vtotal = vtotal * max_vrate / (u32)vrefresh; > + > + /* step 8 */ > + vsync_position = max(OVT_MIN_VSYNC_LE_LINES, > + DIV64_U64_ROUND_UP((u64)OVT_MIN_VSYNC_LE_LINES * > + pixel_clock_rate, > + (u64)htotal * (u64)1000000)); > + > + mode = drm_mode_create(dev); > + > + if (!mode) > + return NULL; > + > + /* step 10 */ > + mode->clock = div_u64(pixel_clock_rate, 1000); > + mode->hdisplay = rid->hactive; > + mode->hsync_start = htotal - OVT_HSYNC_WIDTH * 2; > + mode->hsync_end = mode->hsync_start + OVT_HSYNC_WIDTH; > + mode->htotal = htotal; > + > + mode->vdisplay = rid->vactive; > + mode->vsync_start = vtotal - vsync_position; > + mode->vsync_end = mode->vsync_start + OVT_VSYNC_WIDTH; > + mode->vtotal = vtotal; > + > + return mode; > +} > + > +static u8 find_vic(u8 rid, int rate_idx) > +{ > + if (video_format_frame_rates[rate_idx] > 120 || !find_rid(rid)) > + return 0; > + > + return rid_to_vic[rid][rate_idx - 1]; > +} > + > +/* CTA-861 Video Format Data Block (CTA VFDB) */ > +static int add_modes_from_vfdb(struct drm_connector *connector, > + const struct cea_db *db) > +{ > + const struct drm_display_info *info = &connector->display_info; > + int vfdb_len = cea_db_payload_len(db); > + struct drm_display_mode *mode; > + struct cta_vfd vfd; > + int num_modes = 0; > + int rate_idx; > + int vfd_len; > + int rate; > + int i; > + > + if (!vfdb_len) > + return 0; > + > + vfd_len = (db->data[0] & 0x3); > + > + if (!vfd_len) > + return 0; > + > + vfd_len++; > + vfdb_len--; > + vfdb_len -= (vfdb_len % vfd_len); > + > + for (i = 0; i < vfdb_len; i += vfd_len) { > + parse_cta_vfd(&vfd, &db->data[i + 1], vfd_len); > + > + for (rate_idx = 1; rate_idx < > + ARRAY_SIZE(video_format_frame_rates); rate_idx++) { > + rate = video_format_frame_rates[rate_idx]; > + > + if (!vfd_has_fr(&vfd, rate) || find_vic(vfd.rid, > + rate_idx)) > + continue; > + > + mode = drm_ovt_mode(connector->dev, vfd.rid, rate); > + > + if (!mode) > + continue; > + > + mode->height_mm = info->height_mm; > + mode->width_mm = info->width_mm; > + > + drm_mode_probed_add(connector, mode); > + num_modes++; > + } > + } > + > + return num_modes; > +} > + > /* > * CTA-861 YCbCr 4:2:0 Capability Map Data Block (CTA Y420CMDB) > * > @@ -5342,6 +5805,8 @@ static int add_cea_modes(struct drm_connector > *connector, > /* Add 4:2:0(only) modes present in EDID */ > modes += do_y420vdb_modes(connector, vdb420, > cea_db_payload_len(db) - 1); > + } else if (cea_db_tag(db) == CTA_DB_VIDEO_FORMAT) { > + modes += add_modes_from_vfdb(connector, db); > } > } > cea_db_iter_end(&iter); > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h > index 04f7a7f1f108..272506331634 100644 > --- a/include/drm/drm_edid.h > +++ b/include/drm/drm_edid.h > @@ -463,6 +463,9 @@ struct drm_display_mode * > drm_display_mode_from_cea_vic(struct drm_device *dev, > u8 video_code); > > +struct drm_display_mode *drm_ovt_mode(struct drm_device *dev, int rid, > + int vrefresh); > + > /* Interface based on struct drm_edid */ > const struct drm_edid *drm_edid_alloc(const void *edid, size_t size); > const struct drm_edid *drm_edid_dup(const struct drm_edid *drm_edid); > -- > 2.53.0 >
