drm/edid: Document why we don't bounds check the DispID CEA block start/end

After much head scratching I managed to convince myself that
for_each_displayid_db() has already done the bounds checks for
the DispID CEA data block. Which is why we don't need to repeat
them in cea_db_offsets(). To avoid having to go through that
pain again in the future add a comment which explains this fact.

Cc: Andres Rodriguez <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Acked-by: Alex Deucher <[email protected]>
Reviewed-by: Uma Shankar <[email protected]>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 8ba53472509da87e6376aa7fde3e75347fecb640..61f77377b49ff6e314955531a21fa2c9ef1b66ad 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4017,6 +4017,10 @@ cea_db_offsets(const u8 *cea, int *start, int *end)
         *   no non-DTD data.
         */
        if (cea[0] == DATA_BLOCK_CTA) {
+               /*
+                * for_each_displayid_db() has already verified
+                * that these stay within expected bounds.
+                */
                *start = 3;
                *end = *start + cea[2];
        } else if (cea[0] == CEA_EXT) {