Commit 1a24c364 authored by Jani Nikula's avatar Jani Nikula

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: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/da3dead1752ab16c061f7bd248ac1a4268f7fefb.1617024940.git.jani.nikula@intel.com
parent 4cc4f09e
......@@ -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(*block) <= iter->length &&
iter->idx + sizeof(*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(*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));
}
......@@ -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
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment