On Fri, Jul 13, 2018 at 10:32:15AM -0700, Nathan Ciobanu wrote: > Limit the link training clock recovery loop to 10 failed attempts at > LANEx_CR_DONE per DP 1.4 spec.
Where exactly in the spec? > Some USB-C MST hubs cause us to get > stuck in this loop on hot-plugging indefinitely as > drm_dp_clock_recovery_ok() never returns true and none of the > other conditions occur. Although it seems really bad situation that we need to avoid... > > Signed-off-by: Nathan Ciobanu <[email protected]> > --- > drivers/gpu/drm/i915/intel_dp_link_training.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c > b/drivers/gpu/drm/i915/intel_dp_link_training.c > index 4da6e33c7fa1..66c1a70343ba 100644 > --- a/drivers/gpu/drm/i915/intel_dp_link_training.c > +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c > @@ -129,7 +129,7 @@ static bool intel_dp_link_max_vswing_reached(struct > intel_dp *intel_dp) > intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp) > { > uint8_t voltage; > - int voltage_tries, max_vswing_tries; > + int voltage_tries, max_vswing_tries, cr_tries; > uint8_t link_config[2]; > uint8_t link_bw, rate_select; > > @@ -172,6 +172,7 @@ static bool intel_dp_link_max_vswing_reached(struct > intel_dp *intel_dp) > > voltage_tries = 1; > max_vswing_tries = 0; > + cr_tries = 0; > for (;;) { > uint8_t link_status[DP_LINK_STATUS_SIZE]; > > @@ -215,6 +216,11 @@ static bool intel_dp_link_max_vswing_reached(struct > intel_dp *intel_dp) > if (intel_dp_link_max_vswing_reached(intel_dp)) > ++max_vswing_tries; > > + if (cr_tries == 9) { > + DRM_ERROR("Failed clock recovery 10 times, giving > up!\n"); > + return false; > + } > + ++cr_tries; If I understood correctly this is a global thing for the for(;;) right? Shouldn't we make then like a: - for(;;) + for(cr_tries = 0; cr_tries < 10; cr_tries++) { } + DRM_ERROR("Failed clock recovery 10 times, giving up!\n"); + return false; } Thanks, Rodrigo. > } > } > > -- > 1.9.1 > > _______________________________________________ > Intel-gfx mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
