On Fri, Nov 27, 2015 at 04:30:21PM +0000, Daniel Stone wrote: > Hi, > +marcheu > > On 26 November 2015 at 10:07, Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Wed, Nov 25, 2015 at 05:09:02PM +0530, Thulasimani, Sivakumar wrote: > >> however good to explicitly check for this, > >> following needs to be tested before sending in next patch/merge > >> 1) MST displays verification (Ander's reported on first set of patches) > >> 2) check behavior on sleep - resume (dave&danvet) > >> 3) storm handling needs to be handled as well. (i assume this should be > >> fine, > >> but good to check explicitly) (danvet) > >> > > > > Yeah the storm mitigation will keep on working. What I'm worried about is > > that polling won't work any more: When a storm happens we disable the hpd > > and switch all affected connectors completely to polling. Polling happens > > through the probe helpers in drm_probe_helper.c, and that code exclusively > > uses ->detect callbacks. Which means if we no longer re-probe in detect > > (since we assume hpd works correctly) then this will break the storm > > handling code. > > > > Simplest fix (but a bit a hack) would be to check whether polling is > > enabled at the top of intel_hdmi_detect and if so execute a full probe. > > And not just return the cached values. > > > > Note that storms are only a concern for HDMI, not DP (somehow DP hw is > > less shit). > > Hmm, from what I understand it's a concern on DP as well. Maybe due to > DP->HDMI converters which just pass HPD through? Google's Type-C -> DP > cable crushes all short HPD events - breaking MST short pulses - which > I assume wasn't for no reason: > https://chromium.googlesource.com/chromiumos/platform/ec/+/master/board/dingdong/board.c#27 Yeah right, we do need to keep polling working for DP too, but only for long pulse hpd replacement. As long as a DP cable is plugged in I haven't seen reports of a storm. But indeed hdmi crap can induce a storm on a DP+ connector too. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
