On Wed, 26 Oct 2011 15:06:24 -0200, Eugeni Dodonov eugeni.dodonov@intel.com 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.
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 +/- 1s to 0.184s
Timing results for HD5770 with 'time xrandr' command: Machine 4: from 3.210s to 1.060s
v2: added a module parameter to control this behavior. The idea came from discussion with Jean Delvare.
Just one minor nitpick here... Otherwise it looks a very tasty patch.
+unsigned int drm_ignore_unresponsive_edid = 1; /* Ignore non-responding edid by default */ +EXPORT_SYMBOL(drm_ignore_unresponsive_edid);
This comment would be better in the user-facing description, i.e. (default: true). Do we have a candidate user for exporting the symbol?
MODULE_AUTHOR(CORE_AUTHOR); MODULE_DESCRIPTION(CORE_DESC); MODULE_LICENSE("GPL and additional rights"); MODULE_PARM_DESC(debug, "Enable debug output"); MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]"); MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]"); +MODULE_PARM_DESC(ignore_unresponsive_edid, "Automatically ignore outputs which do not provide EDID after 3 attempts");