drm/displayid: add new displayid section/block iterators
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. v2: - sizeof(struct displayid_block) -> sizeof(*block) (Ville) - remove __ prefix from displayid_iter_block Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/da3dead1752ab16c061f7bd248ac1a4268f7fefb.1617024940.git.jani.nikula@intel.com
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@ -57,3 +57,77 @@ const u8 *drm_find_displayid_extension(const struct edid *edid,
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return displayid;
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}
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void displayid_iter_edid_begin(const struct edid *edid,
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struct displayid_iter *iter)
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{
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memset(iter, 0, sizeof(*iter));
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iter->edid = edid;
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}
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static const struct displayid_block *
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displayid_iter_block(const struct displayid_iter *iter)
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{
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const struct displayid_block *block;
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if (!iter->section)
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return NULL;
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block = (const struct displayid_block *)&iter->section[iter->idx];
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if (iter->idx + sizeof(*block) <= iter->length &&
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iter->idx + sizeof(*block) + block->num_bytes <= iter->length &&
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block->num_bytes > 0)
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return block;
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return NULL;
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}
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const struct displayid_block *
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__displayid_iter_next(struct displayid_iter *iter)
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{
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const struct displayid_block *block;
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if (!iter->edid)
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return NULL;
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if (iter->section) {
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/* current block should always be valid */
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block = displayid_iter_block(iter);
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if (WARN_ON(!block)) {
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iter->section = NULL;
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iter->edid = NULL;
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return NULL;
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}
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/* next block in section */
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iter->idx += sizeof(*block) + block->num_bytes;
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block = displayid_iter_block(iter);
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if (block)
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return block;
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}
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for (;;) {
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iter->section = drm_find_displayid_extension(iter->edid,
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&iter->length,
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&iter->idx,
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&iter->ext_index);
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if (!iter->section) {
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iter->edid = NULL;
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return NULL;
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}
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iter->idx += sizeof(struct displayid_hdr);
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block = displayid_iter_block(iter);
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if (block)
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return block;
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}
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}
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void displayid_iter_end(struct displayid_iter *iter)
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{
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memset(iter, 0, sizeof(*iter));
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}
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@ -108,4 +108,22 @@ const u8 *drm_find_displayid_extension(const struct edid *edid,
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int *length, int *idx,
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int *ext_index);
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/* DisplayID iteration */
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struct displayid_iter {
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const struct edid *edid;
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const u8 *section;
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int length;
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int idx;
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int ext_index;
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};
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void displayid_iter_edid_begin(const struct edid *edid,
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struct displayid_iter *iter);
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const struct displayid_block *
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__displayid_iter_next(struct displayid_iter *iter);
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#define displayid_iter_for_each(__block, __iter) \
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while (((__block) = __displayid_iter_next(__iter)))
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void displayid_iter_end(struct displayid_iter *iter);
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#endif
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