The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 83cbb4d33dc22b0ca1a4e85c6e892c9b729e28d4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025122954-stony-herring-2347@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 83cbb4d33dc22b0ca1a4e85c6e892c9b729e28d4 Mon Sep 17 00:00:00 2001 From: Jani Nikula jani.nikula@intel.com Date: Tue, 28 Oct 2025 22:07:27 +0200 Subject: [PATCH] drm/displayid: add quirk to ignore DisplayID checksum errors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Add a mechanism for DisplayID specific quirks, and add the first quirk to ignore DisplayID section checksum errors.

It would be quite inconvenient to pass existing EDID quirks from drm_edid.c for DisplayID parsing. Not all places doing DisplayID iteration have the quirks readily available, and would have to pass it in all places. Simply add a separate array of DisplayID specific EDID quirks. We do end up checking it every time we iterate DisplayID blocks, but hopefully the number of quirks remains small.

There are a few laptop models with DisplayID checksum failures, leading to higher refresh rates only present in the DisplayID blocks being ignored. Add a quirk for the panel in the machines.

Reported-by: Tiago Martins Araújo tiago.martins.araujo@gmail.com Closes: https://lore.kernel.org/r/CACRbrPGvLP5LANXuFi6z0S7XMbAG4X5y2YOLBDxfOVtfGGqiK... Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14703 Acked-by: Alex Deucher alexander.deucher@amd.com Tested-by: Tiago Martins Araújo tiago.martins.araujo@gmail.com Cc: stable@vger.kernel.org Link: https://patch.msgid.link/c04d81ae648c5f21b3f5b7953f924718051f2798.1761681968... Signed-off-by: Jani Nikula jani.nikula@intel.com

diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c index 20b453d2b854..58d0bb6d2676 100644 --- a/drivers/gpu/drm/drm_displayid.c +++ b/drivers/gpu/drm/drm_displayid.c @@ -9,6 +9,34 @@ #include "drm_crtc_internal.h" #include "drm_displayid_internal.h"

+enum { + QUIRK_IGNORE_CHECKSUM, +}; + +struct displayid_quirk { + const struct drm_edid_ident ident; + u8 quirks; +}; + +static const struct displayid_quirk quirks[] = { + { + .ident = DRM_EDID_IDENT_INIT('C', 'S', 'O', 5142, "MNE007ZA1-5"), + .quirks = BIT(QUIRK_IGNORE_CHECKSUM), + }, +}; + +static u8 get_quirks(const struct drm_edid *drm_edid) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(quirks); i++) { + if (drm_edid_match(drm_edid, &quirks[i].ident)) + return quirks[i].quirks; + } + + return 0; +} + static const struct displayid_header * displayid_get_header(const u8 *displayid, int length, int index) { @@ -23,7 +51,7 @@ displayid_get_header(const u8 *displayid, int length, int index) }

static const struct displayid_header * -validate_displayid(const u8 *displayid, int length, int idx) +validate_displayid(const u8 *displayid, int length, int idx, bool ignore_checksum) { int i, dispid_length; u8 csum = 0; @@ -41,8 +69,11 @@ validate_displayid(const u8 *displayid, int length, int idx) for (i = 0; i < dispid_length; i++) csum += displayid[idx + i]; if (csum) { - DRM_NOTE("DisplayID checksum invalid, remainder is %d\n", csum); - return ERR_PTR(-EINVAL); + DRM_NOTE("DisplayID checksum invalid, remainder is %d%s\n", csum, + ignore_checksum ? " (ignoring)" : ""); + + if (!ignore_checksum) + return ERR_PTR(-EINVAL); }

return base; @@ -52,6 +83,7 @@ static const u8 *find_next_displayid_extension(struct displayid_iter *iter) { const struct displayid_header *base; const u8 *displayid; + bool ignore_checksum = iter->quirks & BIT(QUIRK_IGNORE_CHECKSUM);

displayid = drm_edid_find_extension(iter->drm_edid, DISPLAYID_EXT, &iter->ext_index); if (!displayid) @@ -61,7 +93,7 @@ static const u8 *find_next_displayid_extension(struct displayid_iter *iter) iter->length = EDID_LENGTH - 1; iter->idx = 1;

- base = validate_displayid(displayid, iter->length, iter->idx); + base = validate_displayid(displayid, iter->length, iter->idx, ignore_checksum); if (IS_ERR(base)) return NULL;

@@ -76,6 +108,7 @@ void displayid_iter_edid_begin(const struct drm_edid *drm_edid, memset(iter, 0, sizeof(*iter));

iter->drm_edid = drm_edid; + iter->quirks = get_quirks(drm_edid); }

static const struct displayid_block * diff --git a/drivers/gpu/drm/drm_displayid_internal.h b/drivers/gpu/drm/drm_displayid_internal.h index 957dd0619f5c..5b1b32f73516 100644 --- a/drivers/gpu/drm/drm_displayid_internal.h +++ b/drivers/gpu/drm/drm_displayid_internal.h @@ -167,6 +167,8 @@ struct displayid_iter {

u8 version; u8 primary_use; + + u8 quirks; };

void displayid_iter_edid_begin(const struct drm_edid *drm_edid,