drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers
authorVille Syrjälä <ville.syrjala@linux.intel.com>
Fri, 28 Sep 2018 18:03:59 +0000 (21:03 +0300)
committerVille Syrjälä <ville.syrjala@linux.intel.com>
Mon, 10 Dec 2018 20:33:20 +0000 (22:33 +0200)
commitc978ae9bde582e82a04c63a4071701691dd8b35c
tree9b938d1f3682a2a38822d69b28bbaffcfde0ed4a
parent32658d2c8073699473c28b67f14ad51403ccec5d
drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers

We aren't supposed to force a stop+start between every i2c msg
when performing multi message transfers. This should eg. cause
the DDC segment address to be reset back to 0 between writing
the segment address and reading the actual EDID extension block.

To quote the E-DDC spec:
"... this standard requires that the segment pointer be
 reset to 00h when a NO ACK or a STOP condition is received."

Since we're going to touch this might as well consult the
I2C_M_STOP flag to determine whether we want to force the stop
or not.

Cc: Brian Vincent <brainn@gmail.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=108081
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180928180403.22499-1-ville.syrjala@linux.intel.com
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
drivers/gpu/drm/drm_dp_mst_topology.c