We've been looking recently at some changes that we can make to allow for DP MST to be more reliable on i915. The things that we are looking at are the following. * Change intel_dp_mst_mode_valid() to validate modes against available link bandwidth rather than maximum link bandwidth. This is necessary so that we can properly report to user space the modes that are supported on the link, taking into account link bandwidth that has already been allocated to other virtual channels. This has been a long-standing TODO item in the DP MST code base. (Anusha: New version of patches forthcoming.) * Modify the callbacks between i915 and audio drivers to supply both the port and pipe associated with the audio device, which is required for DP MST audio support. (DK: Patches submitted) * Use the settings from upfront link training to configure the link between the source device and the primary branch to a known good configuration. The current code just assumes that the maximum legal link configuration will work. (Various folks: Upfront patches submitted, MST implementation coming soon.) * Remove some racy behavior around DP MST link training & first time configuration scenarios. In a situation where multiple monitors are connected to a DP MST topology at boot time, we want to make sure that we are only doing upfront and normal link training once each (assuming that the link does not go bad at some point.) Additionally, we want to make sure that the section of code that is only run when intel_dp->active_mst_links == 0 in intel_mst_pre_enable_dp() is also run only one time (normal link training for the MST link is done in this segment of code.) We plan to fix this by adding a MST-specific mutex to intel_dp that will be taken before we check whether upfront link training is needed or before we check if we need to do first-time link setup (intel_dp->active_mst_links == 0.) (Jim: Patches coming soon.) Feedback on any of the above is welcome, as well as any other ideas that folks may have to help DP MST be more reliable. We'd also greatly appreciate some code reviews for the patch sets discussed above. Thanks, Anusha, DK, Jim, and Manasi _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
