drm/edid: do invalid block filtering in-place

Rewrite edid_filter_invalid_blocks() to filter invalid blocks
in-place. The main motivation is to not rely on passed in information on
invalid block count or the allocation size, which will be helpful in
follow-up work on HF-EEODB.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a6ad5e4e7b91338c0d19d7be189af31094e65555.1656494768.git.jani.nikula@intel.com

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 1c761e12820ee0b965efdd5380694a70ce2ef0a7..a80ea0aa7b32eeb147dee9a43e69d4fc34eaa9f8 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2020,33 +2020,37 @@ bool drm_edid_is_valid(struct edid *edid)
 }
 EXPORT_SYMBOL(drm_edid_is_valid);
 
-static struct edid *edid_filter_invalid_blocks(const struct edid *edid,
-                                              int invalid_blocks,
+static struct edid *edid_filter_invalid_blocks(struct edid *edid,
                                               size_t *alloc_size)
 {
-       struct edid *new, *dest_block;
-       int valid_extensions = edid->extensions - invalid_blocks;
-       int i;
+       struct edid *new;
+       int i, valid_blocks = 0;
 
-       *alloc_size = edid_size_by_blocks(valid_extensions + 1);
+       for (i = 0; i < edid_block_count(edid); i++) {
+               const void *src_block = edid_block_data(edid, i);
 
-       new = kmalloc(*alloc_size, GFP_KERNEL);
-       if (!new)
-               goto out;
+               if (edid_block_valid(src_block, i == 0)) {
+                       void *dst_block = (void *)edid_block_data(edid, valid_blocks);
 
-       dest_block = new;
-       for (i = 0; i < edid_block_count(edid); i++) {
-               const void *block = edid_block_data(edid, i);
+                       memmove(dst_block, src_block, EDID_LENGTH);
+                       valid_blocks++;
+               }
+       }
 
-               if (edid_block_valid(block, i == 0))
-                       memcpy(dest_block++, block, EDID_LENGTH);
+       /* We already trusted the base block to be valid here... */
+       if (WARN_ON(!valid_blocks)) {
+               kfree(edid);
+               return NULL;
        }
 
-       new->extensions = valid_extensions;
-       new->checksum = edid_block_compute_checksum(new);
+       edid->extensions = valid_blocks - 1;
+       edid->checksum = edid_block_compute_checksum(edid);
 
-out:
-       kfree(edid);
+       *alloc_size = edid_size_by_blocks(valid_blocks);
+
+       new = krealloc(edid, *alloc_size, GFP_KERNEL);
+       if (!new)
+               kfree(edid);
 
        return new;
 }
@@ -2316,8 +2320,7 @@ static struct edid *_drm_do_get_edid(struct drm_connector *connector,
        if (invalid_blocks) {
                connector_bad_edid(connector, edid, edid_block_count(edid));
 
-               edid = edid_filter_invalid_blocks(edid, invalid_blocks,
-                                                 &alloc_size);
+               edid = edid_filter_invalid_blocks(edid, &alloc_size);
        }
 
 ok: