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drm: give up on edid retries when i2c bus is not responding

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This allows to avoid talking to a non-responding bus repeatedly until we
finally timeout after 15 attempts. We can do this by catching the -ENXIO
error, provided by i2c_algo_bit:bit_doAddress call.

Within the bit_doAddress we already try 3 times to get the edid data, so
if the routine tells us that bus is not responding, it is mostly pointless
to keep re-trying those attempts over and over again until we reach final
number of retries.

This change should fix https://bugs.freedesktop.org/show_bug.cgi?id=41059
and improve overall edid detection timing by 10-30% in most cases, and by
a much larger margin in case of phantom outputs (up to 30x in one worst
case).

Timing results for i915-powered machines for 'time xrandr' command:
Machine 1: from 0.840s to 0.290s
Machine 2: from 0.315s to 0.280s
Machine 3: from +/- 4s to 0.184s

Timing results for HD5770 with 'time xrandr' command:
Machine 4: from 3.210s to 1.060s

Reviewed-by: Chris Wilson <chris@hchris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Tested-by: Sean Finney <seanius@seanius.net>
Tested-by: Soren Hansen <soren@linux2go.dk>
Tested-by: Hernando Torque <sirius@sonnenkinder.org>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41059
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Eugeni Dodonov 2012-01-05 09:34:28 -02:00 committed by Dave Airlie
parent 30388c6e48
commit 9292f37e1f
1 changed files with 5 additions and 0 deletions
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5
drivers/gpu/drm/drm_edid.c
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@ -266,6 +266,11 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf,
}
};
ret = i2c_transfer(adapter, msgs, 2);
if (ret == -ENXIO) {
DRM_DEBUG_KMS("drm: skipping non-existent adapter %s\n",
adapter->name);
break;
}
} while (ret != 2 && --retries);
return ret == 2 ? 0 : -1;