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* [PATCH 1/5] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers
@ 2018-09-28 18:03 Ville Syrjala
  2018-09-28 18:04 ` [PATCH 2/5] drm/dp/mst: Validate REMOTE_I2C_READ harder Ville Syrjala
                   ` (7 more replies)
  0 siblings, 8 replies; 20+ messages in thread
From: Ville Syrjala @ 2018-09-28 18:03 UTC (permalink / raw)
  To: dri-devel; +Cc: Brian Vincent, intel-gfx

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

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

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 5ff1d79b86c4..3b400eab18a2 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3276,6 +3276,7 @@ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs
 		msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
 		msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
 		msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
+		msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
 	}
 	msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
 	msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
-- 
2.16.4

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^ permalink raw reply related	[flat|nested] 20+ messages in thread

end of thread, other threads:[~2018-12-12 12:12 UTC | newest]

Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-09-28 18:03 [PATCH 1/5] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers Ville Syrjala
2018-09-28 18:04 ` [PATCH 2/5] drm/dp/mst: Validate REMOTE_I2C_READ harder Ville Syrjala
2018-12-07 23:11   ` Dhinakaran Pandiyan
2018-09-28 18:04 ` [PATCH 3/5] drm/dp: Implement I2C_M_STOP for i2c-over-aux Ville Syrjala
2018-12-11  2:47   ` Dhinakaran Pandiyan
2018-12-12 10:30     ` Daniel Vetter
2018-12-12 12:12       ` Ville Syrjälä
2018-09-28 18:04 ` [PATCH 4/5] drm/dp/mst: Provide defines for ACK vs. NAK reply type Ville Syrjala
2018-12-08  0:22   ` [Intel-gfx] " Dhinakaran Pandiyan
2018-09-28 18:04 ` [PATCH 5/5] drm/dp/mst: Provide better debugs for NAK replies Ville Syrjala
2018-09-28 21:55   ` kbuild test robot
2018-12-08  0:57   ` [Intel-gfx] " Dhinakaran Pandiyan
2018-12-08  1:05     ` Dhinakaran Pandiyan
2018-10-01 11:55 ` ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/5] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers Patchwork
2018-10-01 12:18 ` ✓ Fi.CI.BAT: success " Patchwork
2018-10-01 13:56 ` ✓ Fi.CI.IGT: " Patchwork
2018-12-07 20:45 ` [PATCH 1/5] " Dhinakaran Pandiyan
2018-12-07 22:52   ` [Intel-gfx] " Dhinakaran Pandiyan
2018-12-10 16:39   ` Ville Syrjälä
2018-12-10 20:09     ` [Intel-gfx] " Dhinakaran Pandiyan

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