On Mon, 09 Sep 2024, Hamza Mahfooz <hamza.mahf...@amd.com> 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.
>
> Suggested-by: Karol Herbst <kher...@redhat.com>
> Signed-off-by: Hamza Mahfooz <hamza.mahf...@amd.com>
> ---
> 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.
Please find some review inline. I'm not finished, ran out of time/steam
a bit, and there's something to work on.
BR,
Jani.
> ---
> drivers/gpu/drm/drm_edid.c | 452 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 452 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 855beafb76ff..01de2117aaf2 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/hdmi.h>
> #include <linux/i2c.h>
> #include <linux/kernel.h>
> @@ -741,6 +742,93 @@ 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[] = {
> + /* RID 0-9 */
> + { 0, 0, 0, 0 },
> + { 1280, 720, 16, 9 },
> + { 1280, 720, 64, 27 },
> + { 1680, 720, 64, 27 },
> + { 1920, 1080, 16, 9 },
> + { 1920, 1080, 64, 27 },
> + { 2560, 1080, 64, 27 },
> + { 3840, 1080, 32, 9 },
> + { 2560, 1440, 16, 9 },
> + { 3440, 1440, 64, 27 },
> + /* RID 10-19 */
> + { 5120, 1440, 32, 9 },
> + { 3840, 2160, 16, 9 },
> + { 3840, 2160, 64, 27 },
> + { 5120, 2160, 64, 27 },
> + { 7680, 2160, 32, 9 },
> + { 5120, 2880, 16, 9 },
> + { 5120, 2880, 64, 27 },
> + { 6880, 2880, 64, 27 },
> + { 10240, 2880, 32, 9 },
> + { 7680, 4320, 16, 9 },
> + /* RID 20-28 */
> + { 7680, 4320, 64, 27 },
> + { 10240, 4320, 64, 27 },
> + { 15360, 4320, 32, 9 },
> + { 11520, 6480, 16, 9 },
> + { 11520, 6480, 64, 27 },
> + { 15360, 6480, 64, 27 },
> + { 15360, 8640, 16, 9 },
> + { 15360, 8640, 64, 27 },
> + { 20480, 8640, 64, 27 },
Designated initializers would remove the need for the /* RID 0-9 */
comments:
[1] = { ... },
> +};
> +
> +/* CTA-861-I Table 12 - AVI InfoFrame Video Format Frame Rate */
> +static const u16 cta_vf_fr[] = {
We don't have to make the names as cryptic as possible. This is only
needed in a few places, so could be video_format_frame_rates or
something. With a comment that it's indexed with rate index.
> + /* Frame Rate 0-7 */
> + 0, 24, 25, 30, 48, 50, 60, 100,
> + /* Frame Rate 8-15 */
> + 120, 144, 200, 240, 300, 360, 400, 480,
What if the preference is for 24/1.001 instead of 24?
> +};
> +
> +/* CTA-861-I Table 13 - RID To VIC Mapping */
> +static const u8 rid_to_vic[][8] = {
> + /* RID 0-9 */
> + {},
> + { 60, 61, 62, 108, 19, 4, 41, 47 },
> + { 65, 66, 67, 109, 68, 69, 70, 71 },
> + { 79, 80, 81, 110, 82, 83, 84, 85 },
> + { 32, 33, 34, 111, 31, 16, 64, 63 },
> + { 72, 73, 74, 112, 75, 76, 77, 78 },
> + { 86, 87, 88, 113, 89, 90, 91, 92 },
> + {},
> + {},
> + {},
> + /* RID 10-19 */
> + {},
> + { 93, 94, 95, 114, 96, 97, 117, 118 },
> + { 103, 104, 105, 116, 106, 107, 119, 120 },
> + { 121, 122, 123, 124, 125, 126, 127, 193 },
> + {},
> + {},
> + {},
> + {},
> + {},
> + { 194, 195, 196, 197, 198, 199, 200, 201 },
> + /* RID 20-28 */
> + { 202, 203, 204, 205, 206, 207, 208, 209 },
> + { 210, 211, 212, 213, 214, 215, 216, 217 },
> + {},
> + {},
> + {},
> + {},
> + {},
> + {},
> + {},
Sparse stuff like this would work better with designated initializers?
[1] = { ... },
Also removes the need for the /* RID 0-9 */ comments.
> +};
> +
> /*
> * From CEA/CTA-861 spec.
> *
> @@ -4131,6 +4219,7 @@ 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 */
> @@ -4972,6 +5061,16 @@ 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;
> @@ -5250,6 +5349,357 @@ 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) : 0x1;
It's a bool member, so true instead of 0x1.
> + vfd->fr144 = vfd_len > 1 ? (data[1] & 0x40) : 0x0;
false instead of 0x0
> + vfd->fr_fact = vfd_len > 1 ? (data[1] & 0x3f) : 0x3;
> + vfd->fr48 = vfd_len > 2 ? (data[2] & 0x1) : 0x0;
false instead of 0x0
> +}
> +
> +static bool vfd_has_fr(const struct cta_vfd *vfd, int rate_idx)
> +{
> + static const u8 factors[] = {
> + 1, 2, 4, 8, 12, 16
> + };
> + u16 rate = cta_vf_fr[rate_idx];
Would make more sense to have int rate parameter instead of rate_idx, so
you don't have to access cta_vf_fr here.
Having it int makes sense because it's used in calculation.
> + u16 factor = 0;
> + unsigned int i;
Just use int, for both.
> +
> + 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;
> +}
> +
> +/* OVT Algorthim as specified in CTA-861-I */
> +static struct drm_display_mode *
> +calculate_ovt_mode(struct drm_connector *connector, const struct cta_rid
> *rid,
> + u16 vrate)
> +{
> + struct drm_display_mode *mode;
> + u32 vtotal_granularity = 1;
> + u32 htotal_granularity;
> + u32 max_vrate = vrate;
> + u64 pixel_clock_rate;
> + u32 vsync_position;
> + u32 min_hblank;
> + u32 min_htotal;
> + u32 min_vtotal;
> + u32 htotal;
> + u32 vtotal;
> +
> + /* step 1 */
> + switch (vrate) {
> + 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)vrate;
> +
> + /* 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(connector->dev);
> +
> + if (!mode)
> + return NULL;
> +
> + 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;
> +}
> +
> +/* CTA-861 Video Format Data Block (CTA VFDB) */
> +static int add_modes_from_vfdb(struct drm_connector *connector,
> + const struct cea_db *db)
> +{
> + struct drm_display_info *info = &connector->display_info;
const
> + int vfdb_len = cea_db_payload_len(db);
> + struct drm_display_mode *mode;
> + struct cta_vfd vfd;
> + int num_modes = 0;
> + int vfd_len;
> + int i;
> + int j;
> +
> + if (!vfdb_len)
> + return 0;
> +
> + vfd_len = (db->data[0] & 0x3) + 1;
> +
> + if (!vfd_len)
> + return 0;
This can never happen on the account of + 1.
> +
> + vfdb_len--;
> +
> + vfdb_len -= (vfdb_len % vfd_len);
Matter of taste, I'd probably write the above lines as:
num_vfd = (vfdb_len - 1) / vfd_len
> +
> + for (i = 0; i < vfdb_len; i += vfd_len) {
And iterate like this:
for (i = 0; i < num_vfd; i++) {
const u8 *vfd = &db->data[1 + i * vfd_len];
Up to you.
> + parse_cta_vfd(&vfd, &db->data[i + 1], vfd_len);
> +
> + if (!vfd.rid || vfd.rid >= ARRAY_SIZE(rids))
> + continue;
> +
> + for (j = 1; j < ARRAY_SIZE(cta_vf_fr); j++) {
Maybe this should be int rate_index instead of j, because it does have a
name in the spec instead of just random iteration?
Probably helps to have
int rate = video_format_frame_rate[rate_index];
> + if (!vfd_has_fr(&vfd, j) ||
Pass in rate there.
> + (cta_vf_fr[j] < 144 && rid_to_vic[vfd.rid][j - 1]))
This makes my head spin. Probably want a function that says what it
does, and can explain in comments inside. Also useful because you'll
need to bounds check rid_to_vic access.
> + continue;
> +
> + mode = calculate_ovt_mode(connector, &rids[vfd.rid],
> + cta_vf_fr[j]);
> +
> + 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)
> *
> @@ -5318,6 +5768,8 @@ 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);
--
Jani Nikula, Intel
