On Wed, Apr 27, 2011 at 7:00 PM, Chris Wilson <ch...@chris-wilson.co.uk> wrote:
> The unusual sequence appears to be: > > [ 30.081906] [drm:intel_dp_i2c_init], i2c_init DPDDC-B > [ 30.082413] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5143003e > [ 30.082415] [drm:intel_dp_i2c_aux_ch], aux_ch failed -110 > [ 30.082921] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5143003e > [ 30.082923] [drm:intel_dp_i2c_aux_ch], aux_ch failed -110 > [ 30.082986] [drm:intel_dp_i2c_init], i2c_init DPDDC-C > [ 30.083193] [drm:intel_dp_i2c_aux_ch], aux_i2c nack > [ 30.083401] [drm:intel_dp_i2c_aux_ch], aux_i2c nack > [ 30.083427] [drm:intel_dp_i2c_init], i2c_init DPDDC-D > [ 30.083934] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5143003e > [ 30.083935] [drm:intel_dp_i2c_aux_ch], aux_ch failed -110 > [ 30.084442] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5143003e > [ 30.084443] [drm:intel_dp_i2c_aux_ch], aux_ch failed -110 > > I wonder what side-effects that explicit NAK from the monitor does during > initialisation of the DP i2c channel. > > During detection we also see a discrepancy for DPDDC-D: > > [ 30.172250] [drm:drm_helper_probe_single_connector_modes], > [CONNECTOR:19:DP-2] > [ 30.172757] [drm:intel_dp_aux_ch], dp_aux_ch timeout status 0x5013003e > [ 30.172758] [drm:ironlake_dp_detect], DPCD: 0000 > > So instead of sending the expected 20 bytes to query the connection, we > just sent the 1 byte header. It seems our problems start with that nack. > > Lets start with a WARN for the AUX_I2C_REPLY_NACK so that I can see the > callpath for that initial probe and so work out the command being sent > that the monitor doesn't like. > -Chris I am keen to help get to the bottom of this but I'll need some direction, it is a long time since I have compiled a kernel, let alone muddled with one. I have got the source packages for my OS kernel and will work out how to build it etc. Looking at the source intel_dp.c seems to be where I might add stuff to get more info based on the above but it might be more productive to tell me what to add than randomly poking it by myself. Paul _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
