Patch "drm/i915: Don't try indexed reads to alternate slave addresses" has been added to the 4.9-stable tree

Patch "drm/i915: Don't try indexed reads to alternate slave addresses" 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: Don't try indexed reads to alternate slave addresses

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-don-t-try-indexed-reads-to-alternate-slave-addresses.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 ae5c631e605a452a5a0e73205a92810c01ed954b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 23 Nov 2017 21:41:56 +0200
Subject: drm/i915: Don't try indexed reads to alternate slave addresses
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

commit ae5c631e605a452a5a0e73205a92810c01ed954b upstream.

We can only specify the one slave address to indexed reads/writes.
Make sure the messages we check are destined to the same slave
address before deciding to do an indexed transfer.

Cc: Daniel Kurtz <djkurtz@chromium.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sean Paul <seanpaul@chromium.org>
Fixes: 56f9eac05489 ("drm/i915/intel_i2c: use INDEX cycles for i2c read transactions")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171123194157.25367-2-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
(cherry picked from commit c4deb62d7821672265b87952bcd1c808f3bf3e8f)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/i915/intel_i2c.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -430,6 +430,7 @@ static bool
 gmbus_is_index_read(struct i2c_msg *msgs, int i, int num)
 {
 	return (i + 1 < num &&
+		msgs[i].addr == msgs[i + 1].addr &&
 		!(msgs[i].flags & I2C_M_RD) && msgs[i].len <= 2 &&
 		(msgs[i + 1].flags & I2C_M_RD));
 }


Patches currently in stable-queue which might be from ville.syrjala@linux.intel.com are

queue-4.9/drm-i915-prevent-zero-length-index-write.patch
queue-4.9/drm-i915-don-t-try-indexed-reads-to-alternate-slave-addresses.patch