Iterating DisplayID blocks across sections (in EDID extensions) is unnecessarily complicated for the caller. Implement DisplayID iterators to go through all blocks in all sections.
Usage example:
const struct displayid_block *block; struct displayid_iter iter;
displayid_iter_edid_begin(edid, &iter); displayid_iter_for_each(block, &iter) { /* operate on block */ } displayid_iter_end(&iter);
When DisplayID is stored in EDID extensions, the DisplayID sections map to extensions as described in VESA DisplayID v1.3 Appendix B: DisplayID as an EDID Extension. This is implemented here.
When DisplayID is stored in its dedicated DDC device 0xA4, according to VESA E-DDC v1.3, different rules apply for the structure. This is not implemented here, as we don't currently use it, but the idea is you'd have a different call for beginning the iteration, for example simply:
displayid_iter_begin(displayid, &iter);
instead of displayid_iter_edid_begin(), and everything else would be hidden away in the iterator functions.
Signed-off-by: Jani Nikula jani.nikula@intel.com --- drivers/gpu/drm/drm_displayid.c | 74 +++++++++++++++++++++++++++++++++ include/drm/drm_displayid.h | 18 ++++++++ 2 files changed, 92 insertions(+)
diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c index 908bbe6feb61..88070267aac9 100644 --- a/drivers/gpu/drm/drm_displayid.c +++ b/drivers/gpu/drm/drm_displayid.c @@ -57,3 +57,77 @@ const u8 *drm_find_displayid_extension(const struct edid *edid,
return displayid; } + +void displayid_iter_edid_begin(const struct edid *edid, + struct displayid_iter *iter) +{ + memset(iter, 0, sizeof(*iter)); + + iter->edid = edid; +} + +static const struct displayid_block * +__displayid_iter_block(const struct displayid_iter *iter) +{ + const struct displayid_block *block; + + if (!iter->section) + return NULL; + + block = (const struct displayid_block *)&iter->section[iter->idx]; + + if (iter->idx + sizeof(struct displayid_block) <= iter->length && + iter->idx + sizeof(struct displayid_block) + block->num_bytes <= iter->length && + block->num_bytes > 0) + return block; + + return NULL; +} + +const struct displayid_block * +__displayid_iter_next(struct displayid_iter *iter) +{ + const struct displayid_block *block; + + if (!iter->edid) + return NULL; + + if (iter->section) { + /* current block should always be valid */ + block = __displayid_iter_block(iter); + if (WARN_ON(!block)) { + iter->section = NULL; + iter->edid = NULL; + return NULL; + } + + /* next block in section */ + iter->idx += sizeof(struct displayid_block) + block->num_bytes; + + block = __displayid_iter_block(iter); + if (block) + return block; + } + + for (;;) { + iter->section = drm_find_displayid_extension(iter->edid, + &iter->length, + &iter->idx, + &iter->ext_index); + if (!iter->section) { + iter->edid = NULL; + return NULL; + } + + iter->idx += sizeof(struct displayid_hdr); + + block = __displayid_iter_block(iter); + if (block) + return block; + } +} + +void displayid_iter_end(struct displayid_iter *iter) +{ + memset(iter, 0, sizeof(*iter)); +} diff --git a/include/drm/drm_displayid.h b/include/drm/drm_displayid.h index 3c6db22a518a..27e06c98db17 100644 --- a/include/drm/drm_displayid.h +++ b/include/drm/drm_displayid.h @@ -108,4 +108,22 @@ const u8 *drm_find_displayid_extension(const struct edid *edid, int *length, int *idx, int *ext_index);
+/* DisplayID iteration */ +struct displayid_iter { + const struct edid *edid; + + const u8 *section; + int length; + int idx; + int ext_index; +}; + +void displayid_iter_edid_begin(const struct edid *edid, + struct displayid_iter *iter); +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); + #endif