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author | Jani Nikula <jani.nikula@intel.com> | 2021-03-29 16:37:17 +0300 |
---|---|---|
committer | Jani Nikula <jani.nikula@intel.com> | 2021-03-31 15:41:43 +0300 |
commit | 1a24c364e48414c6bd16f867c115cb3f4ad1aecc (patch) | |
tree | 5406e849ad73386da2ca78d8e1d5060ddef7c7c7 /drivers/gpu/drm/drm_displayid.c | |
parent | 4cc4f09eaa06178bfa8a5b2c753cefb56e1048c8 (diff) | |
download | linux-1a24c364e48414c6bd16f867c115cb3f4ad1aecc.tar.xz |
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
Diffstat (limited to 'drivers/gpu/drm/drm_displayid.c')
-rw-r--r-- | drivers/gpu/drm/drm_displayid.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c index 908bbe6feb61..5b809bb9fecc 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(*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)); +} |