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

drm/i915: Avoid PPS HW/SW state mismatch due to rounding

to the 4.9-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-avoid-pps-hw-sw-state-mismatch-due-to-rounding.patch and it can be found in the queue-4.9 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 5643205c6340b565a3be0fe0e7305dc4aa551c74 Mon Sep 17 00:00:00 2001

From: Imre Deak imre.deak@intel.com Date: Wed, 29 Nov 2017 19:51:37 +0200 Subject: drm/i915: Avoid PPS HW/SW state mismatch due to rounding MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Imre Deak imre.deak@intel.com

commit 5643205c6340b565a3be0fe0e7305dc4aa551c74 upstream.

We store a SW state of the t11_t12 timing in 100usec units but have to program it in 100msec as required by HW. The rounding used during programming means there will be a mismatch between the SW and HW states of this value triggering a "PPS state mismatch" error. Avoid this by storing the already rounded-up value in the SW state.

Note that we still calculate panel_power_cycle_delay with the finer 100usec granularity to avoid any needless waits using that version of the delay.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103903 Cc: joks joks@linux.pl Signed-off-by: Imre Deak imre.deak@intel.com Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20171129175137.2889-1-imre.dea... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/gpu/drm/i915/intel_dp.c | 6 ++++++ 1 file changed, 6 insertions(+)

--- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -5063,6 +5063,12 @@ intel_dp_init_panel_power_sequencer(stru */ final->t8 = 1; final->t9 = 1; + + /* + * HW has only a 100msec granularity for t11_t12 so round it up + * accordingly. + */ + final->t11_t12 = roundup(final->t11_t12, 100 * 10); }

static void

Patches currently in stable-queue which might be from imre.deak@intel.com are

queue-4.9/drm-i915-avoid-pps-hw-sw-state-mismatch-due-to-rounding.patch