Patch "drm/i915/cnp: Properly handle VBT ddc pin out of bounds." has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915/cnp: Properly handle VBT ddc pin out of bounds.

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-cnp-properly-handle-vbt-ddc-pin-out-of-bounds.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Rodrigo Vivi <[email protected]>
Date: Thu, 25 Jan 2018 14:25:24 -0800
Subject: drm/i915/cnp: Properly handle VBT ddc pin out of bounds.

From: Rodrigo Vivi <[email protected]>

commit 6e3322c226f15bc1838007f5a75566f1482b8e40 upstream.

If the table result is out of bounds on the array map there is something really wrong with VBT pin so we don't return that vbt_pin, but only return 0 instead.

This basically reverts commit 'a8e6f3888b05 ("drm/i915/cnp:
Ignore VBT request for know invalid DDC pin.")'

Also this properly fixes commit 9c3b2689d01f ("drm/i915/cnl:
Map VBT DDC Pin to BSpec DDC Pin.")

v2: Do in a way that we don't break other platforms. (Jani)

v3: Keep debug message (Jani)

v4: Don't mess with 0 mapping was noticed by Jani and
addressed with a simple solution suggested by Lucas that makes this even simpler.

---
 drivers/gpu/drm/i915/intel_bios.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

@@ -1107,6 +1107,7 @@ static void sanitize_aux_ch(struct drm_i
 }
 
 static const u8 cnp_ddc_pin_map[] = {
+	[0] = 0, /* N/A */
 	[DDC_BUS_DDI_B] = GMBUS_PIN_1_BXT,
 	[DDC_BUS_DDI_C] = GMBUS_PIN_2_BXT,
 	[DDC_BUS_DDI_D] = GMBUS_PIN_4_CNP, /* sic */

@@ -1116,9 +1117,9 @@ static const u8 cnp_ddc_pin_map[] = {
 static u8 map_ddc_pin(struct drm_i915_private *dev_priv, u8 vbt_pin)
 {
 	if (HAS_PCH_CNP(dev_priv)) {
-		if (vbt_pin > 0 && vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map))
+		if (vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map)) {
 			return cnp_ddc_pin_map[vbt_pin];
-		if (vbt_pin > GMBUS_PIN_4_CNP) {
+		} else {
 			DRM_DEBUG_KMS("Ignoring alternate pin: VBT claims DDC pin %d, which is not valid for this platform\n", vbt_pin);
 			return 0;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/drm-i915-cnp-properly-handle-vbt-ddc-pin-out-of-bounds.patch queue-4.15/drm-i915-cnp-ignore-vbt-request-for-know-invalid-ddc-pin.patch