On Thu, Aug 16, 2018 at 10:36:43AM +0200, Fredrik Schön wrote: > Shashank, > > Den tors 16 aug. 2018 kl 10:15 skrev Sharma, Shashank > <shashank.sharma@xxxxxxxxx>: > > > > Hey Chris, > > > > > > On 8/16/2018 1:13 PM, Chris Wilson wrote: > > > Quoting Sharma, Shashank (2018-08-16 08:33:36) > > >> Regards > > >> > > >> Shashank > > >> > > >> > > >> On 8/16/2018 12:47 PM, Jani Nikula wrote: > > >>> On Wed, 15 Aug 2018, Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote: > > >>>> On Wed, Aug 15, 2018 at 03:39:40PM -0700, Rodrigo Vivi wrote: > > >>>>> On Mon, Aug 13, 2018 at 07:51:33PM +0200, Fredrik Schön wrote: > > >>>>> > > >>>>> First of all we need to fix the commit subject: > > >>>>> > > >>>>> drm/i915: Increase LSPCON timeout > > >>>>> > > >>>>> (this can be done when merging, no need to resend) > > >>>>> > > >>>>>> 100 ms is not enough time for the LSPCON adapter on Intel NUC devices to > > >>>>>> settle. This causes dropped display modes at driver initialisation. > > >>>>>> > > >>>>>> Increase timeout to 1000 ms. > > >>>>>> > > >>>>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1570392 > > >>>>> Missusage of "Fixes:" tag, please read > > >>>>> > > >>>>> https://01.org/linuxgraphics/gfx-docs/maintainer-tools/drm-intel.html#fixes > > >>>>> > > >>>>> But also no need for resending... could be fixed when merging > > >>>>> > > >>>>> The right one would be: > > >>>>> > > >>>>> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1570392 > > >>>>> Fixes: 357c0ae9198a ("drm/i915/lspcon: Wait for expected LSPCON mode to settle") > > >>>>> Cc: Shashank Sharma <shashank.sharma@xxxxxxxxx> > > >>>>> Cc: Imre Deak <imre.deak@xxxxxxxxx> > > >>>>> Cc: Jani Nikula <jani.nikula@xxxxxxxxx> > > >>>>> Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+ > > >>>>> > > >>>>> Since initial 100 seemed to be empirical and this increase seems to > > >>>>> help other cases I'm in favor of this move so > > >>>>> > > >>>>> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > > >>>>> > > >>>>> However I will wait a bit before merging it > > >>>>> so Imre, Shashank, and/or Jani can take a look here... > > >>>> now, really cc'ing them... > > >>> Shashank? Does this slow down non-LSPCON paths? > > >> This will slow down the lspcon probing and resume part, but both of them > > >> happen only when LSPCON device is found. So to answer your question, > > >> this will not slow down the non-lspcon path, but will slow down the > > >> LSPCON connector resume and probe time. but I would recommend, instead > > >> of increasing it to 1000 ms in a single shot, we might want to gradually > > >> pick this up, on a wake-and-check way. > > > wait_for() checks every [10us, 1ms] until the condition is met, or it > > > times out. So, so long as we don't enter this path for !LPSCON where we > > > know that it will timeout, the wait_for() will only take as long as is > > > required for the connector to settle. > > We wont hit !LSPCON timeout case here, as we have already read the > > dongle signature successfully by now. But I was thinking that, if the > > spec recommends max wait time as 100ms (which is of course doesn't seem > > enough), if we can't detect i2c-over-aux after first 500ms, I guess we > > wont be able to do that in next 500ms too. So is it really ok to wait > > this long in the resume sequence ? > > > > I guess Fredrik can provide some inputs here on if there are some > > experiments behind this number of 1000ms, or this is just a safe bet ? > > > > > My first patch attempt - which is attached to the Redhat and FDO Bugzilla > bugs - added a retry loop around the original 100 ms timeout. The retry loop > did trigger, but never more than once in a row in my testing. > > So possibly 200 ms would be a sufficient timeout, but as the wait_for() loop > terminates early on success I suggested a conservative value of 1000 ms. Since Shashank mentioned 100us came from some spec, maybe the double is already a conservative value. Since there is the concerns of delaying something when LSPCON fails and we are possibly looping on connectors somewhere/somehow I believe we need to have a balanced approach here. could you please try the 200 ms approach on your case there for a while and see how it goes? > > > > Can we do other connectors at the same time, or does probing LSPCON > > > block the system? > > We can do other connectors at the same time in DRM layer at-least, > > LSPCON blocks only this connector. I was curious if are we doing this > > during the resume scenario or is this in the sequential get_connector() > > type of call ? > > - Shashank > > > -Chris > /F > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
