Patch "drm/i915: Avoid PPS HW/SW state mismatch due to rounding" has been added to the 4.9-stable tree

Patch "drm/i915: Avoid PPS HW/SW state mismatch due to rounding" has been added to the 4.9-stable tree

[gregkh]

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;a=summary

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
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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.deak@intel.com
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