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%3Ba=su...

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 stable@vger.kernel.org know about it.

From 6e3322c226f15bc1838007f5a75566f1482b8e40 Mon Sep 17 00:00:00 2001

From: Rodrigo Vivi rodrigo.vivi@intel.com Date: Thu, 25 Jan 2018 14:25:24 -0800 Subject: drm/i915/cnp: Properly handle VBT ddc pin out of bounds.

From: Rodrigo Vivi rodrigo.vivi@intel.com

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.

Fixes: a8e6f3888b05 ("drm/i915/cnp: Ignore VBT request for know invalid DDC pin.") Fixes: 9c3b2689d01f ("drm/i915/cnl: Map VBT DDC Pin to BSpec DDC Pin.") Cc: Radhakrishna Sripada radhakrishna.sripada@intel.com Cc: Jani Nikula jani.nikula@intel.com Cc: Kai Heng Feng kai.heng.feng@canonical.com Cc: Lucas De Marchi lucas.demarchi@intel.com Suggested-by: Lucas De Marchi lucas.demarchi@intel.com Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Reviewed-by: Lucas De Marchi lucas.demarchi@intel.com Tested-by: Kai-Heng Feng kai.heng.feng@canonical.com Link: https://patchwork.freedesktop.org/patch/msgid/20180125222524.22059-1-rodrigo... (cherry picked from commit 3393ce1ed8fc43dbdb83952facaf04e644ca1d54) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

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

--- a/drivers/gpu/drm/i915/intel_bios.c +++ b/drivers/gpu/drm/i915/intel_bios.c @@ -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 rodrigo.vivi@intel.com 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