Patch "drm/i915: cope with large i2c transfers" has been added to the 3.14-stable tree

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

drm/i915: cope with large i2c transfers

to the 3.14-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-cope-with-large-i2c-transfers.patch
and it can be found in the queue-3.14 subdirectory.

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

From: Dmitry Torokhov <[email protected]>
Date: Tue, 21 Apr 2015 09:49:11 -0700
Subject: drm/i915: cope with large i2c transfers

From: Dmitry Torokhov <[email protected]>

commit 9535c4757b881e06fae72a857485ad57c422b8d2 upstream.

The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues.

Let's split larger transfers into digestable chunks. Doing this allows Atmel MXT driver on Pixel 1 function properly (it hasn't since commit 9d8dc3e529a19e427fd379118acd132520935c5d "Input: atmel_mxt_ts - implement T44 message handling" which tries to consume multiple touchscreen/touchpad reports in a single transaction).

---
 drivers/gpu/drm/i915/i915_reg.h  |    1 
 drivers/gpu/drm/i915/intel_i2c.c |   66 +++++++++++++++++++++++++++++++++------
 2 files changed, 57 insertions(+), 10 deletions(-)

@@ -1181,6 +1181,7 @@
 #define   GMBUS_CYCLE_INDEX	(2<<25)
 #define   GMBUS_CYCLE_STOP	(4<<25)
 #define   GMBUS_BYTE_COUNT_SHIFT 16
+#define   GMBUS_BYTE_COUNT_MAX   256U
 #define   GMBUS_SLAVE_INDEX_SHIFT 8
 #define   GMBUS_SLAVE_ADDR_SHIFT 1
 #define   GMBUS_SLAVE_READ	(1<<0)

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

queue-3.14/input-elantech-fix-absolute-mode-setting-on-some-asus-laptops.patch queue-3.14/drm-i915-cope-with-large-i2c-transfers.patch