Re: [v7 1/5] drm/edid: seek for available CEA and DisplayID block from specific EDID block index

On Mon, Mar 14, 2022 at 10:40:47AM +0200, Jani Nikula wrote:

On Sun, 13 Mar 2022, Lee Shawn C shawn.c.lee@intel.com wrote:

...

drm_find_cea_extension() always look for a top level CEA block. Pass ext_index from caller then this function to search next available CEA ext block from a specific EDID block pointer.

v2: save proper extension block index if CTA data information was found in DispalyID block. v3: using different parameters to store CEA and DisplayID block index. configure DisplayID extansion block index before search available DisplayID block.

Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Ville Syrjala ville.syrjala@linux.intel.com Cc: Ankit Nautiyal ankit.k.nautiyal@intel.com Cc: Drew Davenport ddavenport@chromium.org Cc: intel-gfx intel-gfx@lists.freedesktop.org Signed-off-by: Lee Shawn C shawn.c.lee@intel.com

---

drivers/gpu/drm/drm_displayid.c | 10 +++++-- drivers/gpu/drm/drm_edid.c | 53 ++++++++++++++++++--------------- include/drm/drm_displayid.h | 4 +-- 3 files changed, 39 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c index 32da557b960f..31c3e6d7d549 100644 --- a/drivers/gpu/drm/drm_displayid.c +++ b/drivers/gpu/drm/drm_displayid.c @@ -59,11 +59,14 @@ static const u8 *drm_find_displayid_extension(const struct edid *edid, }

void displayid_iter_edid_begin(const struct edid *edid,

• 	       struct displayid_iter *iter)
  

• 	       struct displayid_iter *iter, int *ext_index)
  

Please don't do this. This just ruins the clean approach displayid iterator added.

Instead of making the displayid iterator ugly, and leaking its abstractions, I'll repeat what I said should be done in reply to the very first version of this patch series [1]:

"I think we're going to need abstracted EDID iteration similar to what I've done for DisplayID iteration. We can't have all places reimplementing the iteration like we have now."

This isn't a problem that should be solved by having all the callers hold a bunch of local variables and pass them around to all the functions. Nobody's going to be able to keep track of this anymore. And this series, as it is, makes it harder to fix this properly later on.

I missed your original review comment, so apologies for repeating what you said there already.

I'd agree that passing a starting index to the displayid_iter_* functions is probably not the right direction here. More thoughts below.

BR, Jani.

[1] https://lore.kernel.org/r/87czjf8dik.fsf@intel.com

...

{ memset(iter, 0, sizeof(*iter));

iter->edid = edid;

• if (ext_index)

• iter->ext_index = *ext_index;
  

}

static const struct displayid_block * @@ -126,7 +129,10 @@ __displayid_iter_next(struct displayid_iter *iter) } }

-void displayid_iter_end(struct displayid_iter *iter) +void displayid_iter_end(struct displayid_iter *iter, int *ext_index) {

• if (ext_index)

• *ext_index = iter->ext_index;
  

• memset(iter, 0, sizeof(*iter));

} diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 561f53831e29..78c415aa6889 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -3353,28 +3353,27 @@ const u8 *drm_find_edid_extension(const struct edid *edid, return edid_ext; }

-static const u8 *drm_find_cea_extension(const struct edid *edid) +static const u8 *drm_find_cea_extension(const struct edid *edid,

• 			int *cea_ext_index, int *displayid_ext_index)
  

As discussed above, passing both indices into this function may not be the best approach here. But I think we need to keep track of some kind of state in order to know which was the last CEA block that was returned, and thus this function can return the next one after that, whether it's in the CEA extension block or DisplayID block.

What do you think of using the pointer returned from this function as that state? The caller could pass in a u8* that was returned from a previous call. This function would iterate through the extension blocks and skip the CEA blocks it finds until it finds the passed in pointer, and then return the next one after (or NULL).

An alternative might be to create a linked list of ptrs to the edid extension blocks, and allow a caller to iterate over them in whatever way they need, but I'm not sure how useful that is elsewhere.

...

{ const struct displayid_block *block; struct displayid_iter iter; const u8 *cea;

• int ext_index = 0;

• /* Look for a top level CEA extension block */

• /* FIXME: make callers iterate through multiple CEA ext blocks? */

• cea = drm_find_edid_extension(edid, CEA_EXT, &ext_index);

• /* Look for a CEA extension block from ext_index */

• cea = drm_find_edid_extension(edid, CEA_EXT, cea_ext_index); if (cea) return cea;

  /* CEA blocks can also be found embedded in a DisplayID block */

• displayid_iter_edid_begin(edid, &iter);

• displayid_iter_edid_begin(edid, &iter, displayid_ext_index); displayid_iter_for_each(block, &iter) { if (block->tag == DATA_BLOCK_CTA) { cea = (const u8 *)block; break; } }

• displayid_iter_end(&iter);

• displayid_iter_end(&iter, displayid_ext_index);

  return cea;

} @@ -3643,10 +3642,10 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid) struct drm_device *dev = connector->dev; struct drm_display_mode *mode, *tmp; LIST_HEAD(list);

• int modes = 0;

• int modes = 0, cea_ext_index = 0, displayid_ext_index = 0;

  /* Don't add CEA modes if the CEA extension block is missing */

• if (!drm_find_cea_extension(edid))

• if (!drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index)) return 0;

  /*

@@ -4321,11 +4320,11 @@ static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector, static int add_cea_modes(struct drm_connector *connector, struct edid *edid) {

• const u8 *cea = drm_find_cea_extension(edid);
• const u8 *db, *hdmi = NULL, *video = NULL;

• const u8 *cea, *db, *hdmi = NULL, *video = NULL; u8 dbl, hdmi_len, video_len = 0;

• int modes = 0;

• int modes = 0, cea_ext_index = 0, displayid_ext_index = 0;

• cea = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (cea && cea_revision(cea) >= 3) { int i, start, end;

@@ -4563,6 +4562,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid) const u8 *cea; const u8 *db; int total_sad_count = 0;

• int cea_ext_index = 0, displayid_ext_index = 0; int mnl; int dbl;

@@ -4571,7 +4571,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid) if (!edid) return;

• cea = drm_find_cea_extension(edid);

• cea = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!cea) { DRM_DEBUG_KMS("ELD: no CEA Extension found\n"); return;

@@ -4657,9 +4657,10 @@ int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads) { int count = 0; int i, start, end, dbl;

• int cea_ext_index = 0, displayid_ext_index = 0; const u8 *cea;

• cea = drm_find_cea_extension(edid);

• cea = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!cea) { DRM_DEBUG_KMS("SAD: no CEA Extension found\n"); return 0;

@@ -4719,9 +4720,10 @@ int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb) { int count = 0; int i, start, end, dbl;

• int cea_ext_index = 0, displayid_ext_index = 0; const u8 *cea;

• cea = drm_find_cea_extension(edid);

• cea = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!cea) { DRM_DEBUG_KMS("SAD: no CEA Extension found\n"); return 0;

@@ -4815,8 +4817,9 @@ bool drm_detect_hdmi_monitor(struct edid *edid) const u8 *edid_ext; int i; int start_offset, end_offset;

• int cea_ext_index = 0, displayid_ext_index = 0;

• edid_ext = drm_find_cea_extension(edid);

• edid_ext = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!edid_ext) return false;

@@ -4854,8 +4857,9 @@ bool drm_detect_monitor_audio(struct edid *edid) int i, j; bool has_audio = false; int start_offset, end_offset;

• int cea_ext_index = 0, displayid_ext_index = 0;

• edid_ext = drm_find_cea_extension(edid);

• edid_ext = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!edid_ext) goto end;

@@ -5178,8 +5182,9 @@ static void drm_parse_cea_ext(struct drm_connector *connector, struct drm_display_info *info = &connector->display_info; const u8 *edid_ext; int i, start, end;

• int cea_ext_index = 0, displayid_ext_index = 0;

• edid_ext = drm_find_cea_extension(edid);

• edid_ext = drm_find_cea_extension(edid, &cea_ext_index, &displayid_ext_index); if (!edid_ext) return;

@@ -5311,12 +5316,12 @@ static void drm_update_mso(struct drm_connector *connector, const struct edid *e const struct displayid_block *block; struct displayid_iter iter;

• displayid_iter_edid_begin(edid, &iter);

• displayid_iter_edid_begin(edid, &iter, NULL); displayid_iter_for_each(block, &iter) { if (block->tag == DATA_BLOCK_2_VENDOR_SPECIFIC) drm_parse_vesa_mso_data(connector, block); }

• displayid_iter_end(&iter);

• displayid_iter_end(&iter, NULL);

}

/* A connector has no EDID information, so we've got no EDID to compute quirks from. Reset @@ -5516,13 +5521,13 @@ static int add_displayid_detailed_modes(struct drm_connector *connector, struct displayid_iter iter; int num_modes = 0;

• displayid_iter_edid_begin(edid, &iter);

• displayid_iter_edid_begin(edid, &iter, NULL); displayid_iter_for_each(block, &iter) { if (block->tag == DATA_BLOCK_TYPE_1_DETAILED_TIMING || block->tag == DATA_BLOCK_2_TYPE_7_DETAILED_TIMING) num_modes += add_displayid_detailed_1_modes(connector, block); }

• displayid_iter_end(&iter);

• displayid_iter_end(&iter, NULL);

  return num_modes;

} @@ -6164,12 +6169,12 @@ void drm_update_tile_info(struct drm_connector *connector,

connector->has_tile = false;

• displayid_iter_edid_begin(edid, &iter);

• displayid_iter_edid_begin(edid, &iter, NULL); displayid_iter_for_each(block, &iter) { if (block->tag == DATA_BLOCK_TILED_DISPLAY) drm_parse_tiled_block(connector, block); }

• displayid_iter_end(&iter);

• displayid_iter_end(&iter, NULL);

  if (!connector->has_tile && connector->tile_group) { drm_mode_put_tile_group(connector->dev, connector->tile_group);

diff --git a/include/drm/drm_displayid.h b/include/drm/drm_displayid.h index 7ffbd9f7bfc7..15442a161c11 100644 --- a/include/drm/drm_displayid.h +++ b/include/drm/drm_displayid.h @@ -150,11 +150,11 @@ struct displayid_iter { };

void displayid_iter_edid_begin(const struct edid *edid,

• 	       struct displayid_iter *iter);
  

• 	       struct displayid_iter *iter, int *ext_index);
  

const struct displayid_block * __displayid_iter_next(struct displayid_iter *iter); #define displayid_iter_for_each(__block, __iter) \ while (((__block) = __displayid_iter_next(__iter))) -void displayid_iter_end(struct displayid_iter *iter); +void displayid_iter_end(struct displayid_iter *iter, int *ext_index);

#endif

-- Jani Nikula, Intel Open Source Graphics Center