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Message-ID: <87h695y29i.fsf@intel.com>
Date: Mon, 21 Oct 2024 17:11:21 +0300
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula@...il.com>
Cc: maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch,
skhan@...uxfoundation.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/edid: transition to passing struct cea_db * to
cae_db_payload_len
On Mon, 21 Oct 2024, Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula@...il.com> wrote:
> On Mon, Oct 21, 2024 at 7:12 PM Jani Nikula <jani.nikula@...ux.intel.com> wrote:
>>
>> On Fri, 11 Oct 2024, Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula@...il.com> wrote:
>> > Address the FIXME in cea_db_payload_len
>> > Transition to passing struct cea_db * everywhere
>>
>> You've misunderstood the comment. The point is to pass struct cea_db *
>> around, not to stick to u8 * and drop calls to cea_db_payload_len().
>>
> Thank you for the response.
> Would below be an acceptable change for the FIXME?
> 1. Use a macro to extract length from (db->tag_length & 0x1f)
No, why would you do that? We have the function.
> 2. Pass struct cea_db * to all individual parsers
Yes. Look at all callers of cea_db_payload_len() and propagate struct
cea_db *db to them instead of u8 *db.
The related and relevant other FIXME comment is in drm_parse_cea_ext():
/* FIXME: convert parsers to use struct cea_db */
That's where you should start. Some of the parsers already handle struct
cea_db, and others need to use const u8 *data.
Please don't cram all of this in one patch, probably start off function
by function. It's easier to squash patches later than to split.
Yes.
> 3. Use db->data? / convert to u8 and use db[i] where needed.
There's cea_db_data() for this. The slightly annoying part is that for
extended tags and vendor blocks the "actual" data is at an offset. See
for example drm_parse_hdmi_vsdb_video(). It's good that the len checks
and db dereferences match, and that they match what's written in the
spec, but it's a bit funny in the code. Maybe not something you need to
worry about at this point.
BR,
Jani.
>
>> BR,
>> Jani.
>>
>> >
>> > Precompute the payload length in drm_parse_cea_ext and pass to
>> > individual parsers to avoid casting struct cea_db pointer to u8
>> > pointer where length is needed.
>> >
>> > Since the type of payload length is inconsistent in the file,
>> > use u8, u16 where it was already in place, use int elsewhere.
>> >
>> > Signed-off-by: Vamsi Krishna Brahmajosyula <vamsikrishna.brahmajosyula@...il.com>
>> > ---
>> > drivers/gpu/drm/drm_edid.c | 63 ++++++++++++++++----------------------
>> > 1 file changed, 27 insertions(+), 36 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> > index 855beafb76ff..80442e8b8ac6 100644
>> > --- a/drivers/gpu/drm/drm_edid.c
>> > +++ b/drivers/gpu/drm/drm_edid.c
>> > @@ -4977,11 +4977,8 @@ static int cea_db_tag(const struct cea_db *db)
>> > return db->tag_length >> 5;
>> > }
>> >
>> > -static int cea_db_payload_len(const void *_db)
>> > +static int cea_db_payload_len(const struct cea_db *db)
>> > {
>> > - /* FIXME: Transition to passing struct cea_db * everywhere. */
>> > - const struct cea_db *db = _db;
>> > -
>> > return db->tag_length & 0x1f;
>> > }
>> >
>> > @@ -5432,22 +5429,18 @@ static uint8_t hdr_metadata_type(const u8 *edid_ext)
>> > }
>> >
>> > static void
>> > -drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db)
>> > +drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db, const u16 payload_len)
>> > {
>> > - u16 len;
>> > -
>> > - len = cea_db_payload_len(db);
>> > -
>> > connector->hdr_sink_metadata.hdmi_type1.eotf =
>> > eotf_supported(db);
>> > connector->hdr_sink_metadata.hdmi_type1.metadata_type =
>> > hdr_metadata_type(db);
>> >
>> > - if (len >= 4)
>> > + if (payload_len >= 4)
>> > connector->hdr_sink_metadata.hdmi_type1.max_cll = db[4];
>> > - if (len >= 5)
>> > + if (payload_len >= 5)
>> > connector->hdr_sink_metadata.hdmi_type1.max_fall = db[5];
>> > - if (len >= 6) {
>> > + if (payload_len >= 6) {
>> > connector->hdr_sink_metadata.hdmi_type1.min_cll = db[6];
>> >
>> > /* Calculate only when all values are available */
>> > @@ -5457,20 +5450,18 @@ drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db)
>> >
>> > /* HDMI Vendor-Specific Data Block (HDMI VSDB, H14b-VSDB) */
>> > static void
>> > -drm_parse_hdmi_vsdb_audio(struct drm_connector *connector, const u8 *db)
>> > +drm_parse_hdmi_vsdb_audio(struct drm_connector *connector, const u8 *db, u8 payload_len)
>> > {
>> > - u8 len = cea_db_payload_len(db);
>> > -
>> > - if (len >= 6 && (db[6] & (1 << 7)))
>> > + if (payload_len >= 6 && (db[6] & (1 << 7)))
>> > connector->eld[DRM_ELD_SAD_COUNT_CONN_TYPE] |= DRM_ELD_SUPPORTS_AI;
>> >
>> > - if (len >= 10 && hdmi_vsdb_latency_present(db)) {
>> > + if (payload_len >= 10 && hdmi_vsdb_latency_present(db)) {
>> > connector->latency_present[0] = true;
>> > connector->video_latency[0] = db[9];
>> > connector->audio_latency[0] = db[10];
>> > }
>> >
>> > - if (len >= 12 && hdmi_vsdb_i_latency_present(db)) {
>> > + if (payload_len >= 12 && hdmi_vsdb_i_latency_present(db)) {
>> > connector->latency_present[1] = true;
>> > connector->video_latency[1] = db[11];
>> > connector->audio_latency[1] = db[12];
>> > @@ -5695,7 +5686,7 @@ static void drm_edid_to_eld(struct drm_connector *connector,
>> > case CTA_DB_VENDOR:
>> > /* HDMI Vendor-Specific Data Block */
>> > if (cea_db_is_hdmi_vsdb(db))
>> > - drm_parse_hdmi_vsdb_audio(connector, (const u8 *)db);
>> > + drm_parse_hdmi_vsdb_audio(connector, (const u8 *)db, len);
>> > break;
>> > default:
>> > break;
>> > @@ -6122,7 +6113,7 @@ static void drm_parse_ycbcr420_deep_color_info(struct drm_connector *connector,
>> > }
>> >
>> > static void drm_parse_dsc_info(struct drm_hdmi_dsc_cap *hdmi_dsc,
>> > - const u8 *hf_scds)
>> > + const u8 *hf_scds, int payload_len)
>> > {
>> > hdmi_dsc->v_1p2 = hf_scds[11] & DRM_EDID_DSC_1P2;
>> >
>> > @@ -6142,7 +6133,7 @@ static void drm_parse_dsc_info(struct drm_hdmi_dsc_cap *hdmi_dsc,
>> > /* Supports min 8 BPC if DSC 1.2 is supported*/
>> > hdmi_dsc->bpc_supported = 8;
>> >
>> > - if (cea_db_payload_len(hf_scds) >= 12 && hf_scds[12]) {
>> > + if (payload_len >= 12 && hf_scds[12]) {
>> > u8 dsc_max_slices;
>> > u8 dsc_max_frl_rate;
>> >
>> > @@ -6188,13 +6179,13 @@ static void drm_parse_dsc_info(struct drm_hdmi_dsc_cap *hdmi_dsc,
>> > }
>> > }
>> >
>> > - if (cea_db_payload_len(hf_scds) >= 13 && hf_scds[13])
>> > + if (payload_len >= 13 && hf_scds[13])
>> > hdmi_dsc->total_chunk_kbytes = hf_scds[13] & DRM_EDID_DSC_TOTAL_CHUNK_KBYTES;
>> > }
>> >
>> > /* Sink Capability Data Structure */
>> > static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
>> > - const u8 *hf_scds)
>> > + const u8 *hf_scds, int payload_len)
>> > {
>> > struct drm_display_info *info = &connector->display_info;
>> > struct drm_hdmi_info *hdmi = &info->hdmi;
>> > @@ -6247,8 +6238,8 @@ static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
>> >
>> > drm_parse_ycbcr420_deep_color_info(connector, hf_scds);
>> >
>> > - if (cea_db_payload_len(hf_scds) >= 11 && hf_scds[11]) {
>> > - drm_parse_dsc_info(hdmi_dsc, hf_scds);
>> > + if (payload_len >= 11 && hf_scds[11]) {
>> > + drm_parse_dsc_info(hdmi_dsc, hf_scds, payload_len);
>> > dsc_support = true;
>> > }
>> >
>> > @@ -6259,7 +6250,7 @@ static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
>> > }
>> >
>> > static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>> > - const u8 *hdmi)
>> > + const u8 *hdmi, const u8 payload_len)
>> > {
>> > struct drm_display_info *info = &connector->display_info;
>> > unsigned int dc_bpc = 0;
>> > @@ -6267,7 +6258,7 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>> > /* HDMI supports at least 8 bpc */
>> > info->bpc = 8;
>> >
>> > - if (cea_db_payload_len(hdmi) < 6)
>> > + if (payload_len < 6)
>> > return;
>> >
>> > if (hdmi[6] & DRM_EDID_HDMI_DC_30) {
>> > @@ -6320,18 +6311,17 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>> >
>> > /* HDMI Vendor-Specific Data Block (HDMI VSDB, H14b-VSDB) */
>> > static void
>> > -drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db)
>> > +drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db, const u8 payload_len)
>> > {
>> > struct drm_display_info *info = &connector->display_info;
>> > - u8 len = cea_db_payload_len(db);
>> >
>> > info->is_hdmi = true;
>> >
>> > info->source_physical_address = (db[4] << 8) | db[5];
>> >
>> > - if (len >= 6)
>> > + if (payload_len >= 6)
>> > info->dvi_dual = db[6] & 1;
>> > - if (len >= 7)
>> > + if (payload_len >= 7)
>> > info->max_tmds_clock = db[7] * 5000;
>> >
>> > /*
>> > @@ -6340,14 +6330,14 @@ drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db)
>> > * HDMI infoframe support was first added in HDMI 1.4. Assume the sink
>> > * supports infoframes if HDMI_Video_present is set.
>> > */
>> > - if (len >= 8 && db[8] & BIT(5))
>> > + if (payload_len >= 8 && db[8] & BIT(5))
>> > info->has_hdmi_infoframe = true;
>> >
>> > drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI: DVI dual %d, max TMDS clock %d kHz\n",
>> > connector->base.id, connector->name,
>> > info->dvi_dual, info->max_tmds_clock);
>> >
>> > - drm_parse_hdmi_deep_color_info(connector, db);
>> > + drm_parse_hdmi_deep_color_info(connector, db, payload_len);
>> > }
>> >
>> > /*
>> > @@ -6410,12 +6400,13 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>> > cea_db_iter_for_each(db, &iter) {
>> > /* FIXME: convert parsers to use struct cea_db */
>> > const u8 *data = (const u8 *)db;
>> > + int len = cea_db_payload_len(db);
>> >
>> > if (cea_db_is_hdmi_vsdb(db))
>> > - drm_parse_hdmi_vsdb_video(connector, data);
>> > + drm_parse_hdmi_vsdb_video(connector, data, len);
>> > else if (cea_db_is_hdmi_forum_vsdb(db) ||
>> > cea_db_is_hdmi_forum_scdb(db))
>> > - drm_parse_hdmi_forum_scds(connector, data);
>> > + drm_parse_hdmi_forum_scds(connector, data, len);
>> > else if (cea_db_is_microsoft_vsdb(db))
>> > drm_parse_microsoft_vsdb(connector, data);
>> > else if (cea_db_is_y420cmdb(db))
>> > @@ -6425,7 +6416,7 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>> > else if (cea_db_is_vcdb(db))
>> > drm_parse_vcdb(connector, data);
>> > else if (cea_db_is_hdmi_hdr_metadata_block(db))
>> > - drm_parse_hdr_metadata_block(connector, data);
>> > + drm_parse_hdr_metadata_block(connector, data, len);
>> > else if (cea_db_tag(db) == CTA_DB_VIDEO)
>> > parse_cta_vdb(connector, db);
>> > else if (cea_db_tag(db) == CTA_DB_AUDIO)
>> >
>> > base-commit: 1d227fcc72223cbdd34d0ce13541cbaab5e0d72f
>>
>> --
>> Jani Nikula, Intel
> Thanks,
> Vamsi
--
Jani Nikula, Intel
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