3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Eugeni Dodonov <eugeni.dodo...@intel.com> commit 9292f37e1f5c79400254dca46f83313488093825 upstream. 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 <ch...@hchris-wilson.co.uk> Reviewed-by: Keith Packard <kei...@keithp.com> Tested-by: Sean Finney <sean...@seanius.net> Tested-by: Soren Hansen <so...@linux2go.dk> Tested-by: Hernando Torque <sir...@sonnenkinder.org> Tested-by: Mike Lothian <m...@fireburn.co.uk> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41059 Signed-off-by: Eugeni Dodonov <eugeni.dodo...@intel.com> Signed-off-by: Dave Airlie <airl...@redhat.com> Signed-off-by: Ben Hutchings <b...@decadent.org.uk> --- drivers/gpu/drm/drm_edid.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index ece03fc..54a4efa 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
