[Intel-gfx] [PATCH 07/12] drm/edid: split drm_edid_block_valid() to check and act parts
Jani Nikula
jani.nikula at intel.com
Tue Mar 29 18:42:14 UTC 2022
Add edid_block_check() that only checks the EDID block validity, without
any actions. Turns out it's simple and crystal clear.
Rewrite drm_edid_block_valid() around it, keeping all the functionality
fairly closely the same, warts and all. Turns out it's incredibly
complicated for a function you'd expect to be simple, with all the
fixing and printing and special casing. (Maybe we'll want to simplify it
in the future.)
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
drivers/gpu/drm/drm_edid.c | 150 ++++++++++++++++++++++---------------
1 file changed, 88 insertions(+), 62 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 481643751d10..04eb6949c9c8 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1668,10 +1668,55 @@ bool drm_edid_are_equal(const struct edid *edid1, const struct edid *edid2)
}
EXPORT_SYMBOL(drm_edid_are_equal);
+enum edid_block_status {
+ EDID_BLOCK_OK = 0,
+ EDID_BLOCK_NULL,
+ EDID_BLOCK_HEADER_CORRUPT,
+ EDID_BLOCK_HEADER_REPAIR,
+ EDID_BLOCK_HEADER_FIXED,
+ EDID_BLOCK_CHECKSUM,
+ EDID_BLOCK_VERSION,
+};
+
+static enum edid_block_status edid_block_check(const void *_block, bool base)
+{
+ const struct edid *block = _block;
+
+ if (!block)
+ return EDID_BLOCK_NULL;
+
+ if (base) {
+ int score = drm_edid_header_is_valid(block);
+
+ if (score < clamp(edid_fixup, 6, 8))
+ return EDID_BLOCK_HEADER_CORRUPT;
+
+ if (score < 8)
+ return EDID_BLOCK_HEADER_REPAIR;
+ }
+
+ if (edid_block_compute_checksum(block) != edid_block_get_checksum(block))
+ return EDID_BLOCK_CHECKSUM;
+
+ if (base) {
+ if (block->version != 1)
+ return EDID_BLOCK_VERSION;
+ }
+
+ return EDID_BLOCK_OK;
+}
+
+static bool edid_block_status_valid(enum edid_block_status status, int tag)
+{
+ return status == EDID_BLOCK_OK ||
+ status == EDID_BLOCK_HEADER_FIXED ||
+ (status == EDID_BLOCK_CHECKSUM && tag == CEA_EXT);
+}
+
/**
* drm_edid_block_valid - Sanity check the EDID block (base or extension)
* @raw_edid: pointer to raw EDID block
- * @block: type of block to validate (0 for base, extension otherwise)
+ * @block_num: type of block to validate (0 for base, extension otherwise)
* @print_bad_edid: if true, dump bad EDID blocks to the console
* @edid_corrupt: if true, the header or checksum is invalid
*
@@ -1680,88 +1725,69 @@ EXPORT_SYMBOL(drm_edid_are_equal);
*
* Return: True if the block is valid, false otherwise.
*/
-bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid,
+bool drm_edid_block_valid(u8 *_block, int block_num, bool print_bad_edid,
bool *edid_corrupt)
{
- u8 csum;
- struct edid *edid = (struct edid *)raw_edid;
+ struct edid *block = (struct edid *)_block;
+ enum edid_block_status status;
+ bool base = block_num == 0;
+ bool valid;
- if (WARN_ON(!raw_edid))
+ if (WARN_ON(!block))
return false;
- if (edid_fixup > 8 || edid_fixup < 0)
- edid_fixup = 6;
-
- if (block == 0) {
- int score = drm_edid_header_is_valid(raw_edid);
+ status = edid_block_check(block, base);
+ if (status == EDID_BLOCK_HEADER_REPAIR) {
+ DRM_DEBUG("Fixing EDID header, your hardware may be failing\n");
+ edid_header_fix(block);
- if (score == 8) {
- if (edid_corrupt)
- *edid_corrupt = false;
- } else if (score >= edid_fixup) {
- /* Displayport Link CTS Core 1.2 rev1.1 test 4.2.2.6
- * The corrupt flag needs to be set here otherwise, the
- * fix-up code here will correct the problem, the
- * checksum is correct and the test fails
- */
- if (edid_corrupt)
- *edid_corrupt = true;
- DRM_DEBUG("Fixing EDID header, your hardware may be failing\n");
- edid_header_fix(raw_edid);
- } else {
- if (edid_corrupt)
- *edid_corrupt = true;
- goto bad;
- }
+ /* Retry with fixed header, update status if that worked. */
+ status = edid_block_check(block, base);
+ if (status == EDID_BLOCK_OK)
+ status = EDID_BLOCK_HEADER_FIXED;
}
- csum = edid_block_compute_checksum(raw_edid);
- if (csum != edid_block_get_checksum(raw_edid)) {
- if (edid_corrupt)
+ if (edid_corrupt) {
+ /*
+ * Unknown major version isn't corrupt but we can't use it. Only
+ * the base block can reset edid_corrupt to false.
+ */
+ if (base && (status == EDID_BLOCK_OK || status == EDID_BLOCK_VERSION))
+ *edid_corrupt = false;
+ else if (status != EDID_BLOCK_OK)
*edid_corrupt = true;
-
- /* allow CEA to slide through, switches mangle this */
- if (edid_block_tag(raw_edid) == CEA_EXT) {
- DRM_DEBUG("EDID checksum is invalid, remainder is %d\n", csum);
- DRM_DEBUG("Assuming a KVM switch modified the CEA block but left the original checksum\n");
- } else {
- if (print_bad_edid)
- DRM_NOTE("EDID checksum is invalid, remainder is %d\n", csum);
-
- goto bad;
- }
}
- /* per-block-type checks */
- switch (edid_block_tag(raw_edid)) {
- case 0: /* base */
- if (edid->version != 1) {
- DRM_NOTE("EDID has major version %d, instead of 1\n", edid->version);
- goto bad;
+ /* Determine whether we can use this block with this status. */
+ valid = edid_block_status_valid(status, edid_block_tag(block));
+
+ /* Some fairly random status printouts. */
+ if (status == EDID_BLOCK_CHECKSUM) {
+ if (valid) {
+ DRM_DEBUG("EDID block checksum is invalid, remainder is %d\n",
+ edid_block_compute_checksum(block));
+ DRM_DEBUG("Assuming a KVM switch modified the block but left the original checksum\n");
+ } else if (print_bad_edid) {
+ DRM_NOTE("EDID block checksum is invalid, remainder is %d\n",
+ edid_block_compute_checksum(block));
}
-
- if (edid->revision > 4)
- DRM_DEBUG("EDID minor > 4, assuming backward compatibility\n");
- break;
-
- default:
- break;
+ } else if (status == EDID_BLOCK_VERSION) {
+ DRM_NOTE("EDID has major version %d, instead of 1\n",
+ block->version);
}
- return true;
-
-bad:
- if (print_bad_edid) {
- if (edid_is_zero(raw_edid, EDID_LENGTH)) {
+ if (!valid && print_bad_edid) {
+ if (edid_is_zero(block, EDID_LENGTH)) {
pr_notice("EDID block is all zeroes\n");
} else {
pr_notice("Raw EDID:\n");
print_hex_dump(KERN_NOTICE,
" \t", DUMP_PREFIX_NONE, 16, 1,
- raw_edid, EDID_LENGTH, false);
+ block, EDID_LENGTH, false);
}
}
- return false;
+
+ return valid;
}
EXPORT_SYMBOL(drm_edid_block_valid);
--
2.30.2
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