Hi Dave,

Is it ok if I merge this through my -next tree? Otherwise please consider merging this for 3.4.

Yours, Daniel

On Thu, Jan 05, 2012 at 09:34:28AM -0200, Eugeni Dodonov wrote:

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

---

drivers/gpu/drm/drm_edid.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 3e927ce..fb6c26c 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -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;

-- 1.7.8

---

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