On Tue, 15 Nov 2016, Manasi Navare <manasi.d.navare@xxxxxxxxx> wrote: > Submitting new series that adds proper commit messages/cover letter > and kernel documentation. It also moved the set_link_status function > to drm core so other kernel drivers can make use of it. > > The idea presented in these patches is to address link training failure > in a way that: > a) changes the current happy day scenario as little as possible, to avoid > regressions, b) can be implemented the same way by all drm drivers, c) > is still opt-in for the drivers and userspace, and opting out doesn't > regress the user experience, d) doesn't prevent drivers from > implementing better or alternate approaches, possibly without userspace > involvement. And, of course, handles all the issues presented. > > The solution is to add a "link status" connector property. In the usual > happy day scenario, this is always "good". If something fails during or > after a mode set, the kernel driver can set the link status to "bad", > prune the mode list based on new information as necessary, and send a > hotplug uevent for userspace to have it re-check the valid modes through > getconnector, and try again. If the theoretical capabilities of the link > can't be reached, the mode list is trimmed based on that. > > If the userspace is not aware of the property, the user experience is > the same as it currently is. If the userspace is aware of the property, > it has a chance to improve user experience. If a drm driver does not > modify the property (it stays "good"), the user experience is the same > as it currently is. A drm driver can also choose to try to handle more > of the failures in kernel, hardware not limiting, or it can choose to > involve userspace more. Up to the drivers. > > The reason for adding the property is to handle link training failures, > but it is not limited to DP or link training. For example, if we > implement asynchronous setcrtc, we can use this to report any failures > in that. > > Finally, while DP CTS compliance is advertized (which is great, and > could be made to work similarly for all drm drivers), this can be used > for the more important goal of improving user experience on link > training failures, by avoiding black screens. Since I went through the trouble of writing this, you might as well add it to patch 1/5 commit message so it benefits the posterity. > Acked-by: Tony Cheng <tony.cheng@xxxxxxx> > Acked-by: Harry Wentland <Harry.wentland@xxxxxxx> These must go to patch 1/5 commit message. BR, Jani. > > Manasi Navare (5): > drm: Add a new connector property for link status > drm: Set DRM connector link status property > drm/i915: Update CRTC state if connector link status property changed > drm/i915: Find fallback link rate/lane count > drm/i915: Implement Link Rate fallback on Link training failure > > drivers/gpu/drm/drm_atomic_helper.c | 7 ++ > drivers/gpu/drm/drm_connector.c | 55 ++++++++++ > drivers/gpu/drm/i915/intel_ddi.c | 21 +++- > drivers/gpu/drm/i915/intel_dp.c | 144 +++++++++++++++++++++++++- > drivers/gpu/drm/i915/intel_dp_link_training.c | 12 ++- > drivers/gpu/drm/i915/intel_drv.h | 10 +- > include/drm/drm_connector.h | 9 +- > include/drm/drm_crtc.h | 5 + > include/uapi/drm/drm_mode.h | 4 + > 9 files changed, 257 insertions(+), 10 deletions(-) -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
