[Intel-gfx] [PATCH] drm/i915/dp: return proper DPRX link training result

[Imre Deak]

On Wed, Aug 18, 2021 at 06:09:43PM +0300, Lee, Shawn C wrote:
> On Tue, 2021-07-07, Lee Shawn C <shawn.c.lee at intel.com> wrote:
> >On Tue, 2021-07-07, Almahallawy, Khaled <khaled.almahallawy at intel.com> wrote:
> >>I believe Imre's LT fallback:
> >>https://github.com/ideak/linux/commits/linktraining-fallback-fix  and Chrome user space fix:
> >>https://chromium-review.googlesource.com/c/chromium/src/+/3003487
> >>should address Chrome concerns for LT failure and LTTPRs
> >>
> >
> >Thanks for comment! The new fallback patch should help on this DPRX problem.
> >One more thing. If driver did not handle DPRX link train failed properly.
> >It would impact link layer compliance test case in below.
> >
> >400.3.1.3
> >400.3.1.4
> >400.3.1.6
> >400.3.1.12
> >400.3.1.13
> >400.3.1.14
> >
> >Best regards,
> >Shawn
> >
> 
> Hi all, before Imre's patch series land on upstream driver. The link train failed
> handling works for LTTPR only. But DPRX does not. Could you please consider to have
> this change as temporary solution? Thanks!

I sent already fixing this, see
https://lore.kernel.org/intel-gfx/20201027133600.3656665-1-imre.deak@intel.com/

but it fell through the cracks. Applied now your patch, thanks.

> 
> Best regards,
> Shawn
> 
> >>Thanks
> >>Khaled
> >>
> >>On Tue, 2021-07-06 at 23:25 +0800, Lee Shawn C wrote:
> >>> After DPRX link training, intel_dp_link_train_phy() did not return
> >>> the training result properly. If link training failed,
> >>> i915 driver would not run into link train fallback function.
> >>> And no hotplug uevent would be received by user space application.
> >>>
> >>> Fixes: b30edfd8d0b4 ("drm/i915: Switch to LTTPR non-transparent mode
> >>> link training")
> >>> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> >>> Cc: Imre Deak <imre.deak at intel.com>
> >>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> >>> Cc: Cooper Chiou <cooper.chiou at intel.com>
> >>> Cc: William Tseng <william.tseng at intel.com>
> >>> Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
> >>> ---
> >>>  drivers/gpu/drm/i915/display/intel_dp_link_training.c | 2 +-
> >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> >>> b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> >>> index 08bceae40aa8..e44788b2c564 100644
> >>> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> >>> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> >>> @@ -849,7 +849,7 @@ intel_dp_link_train_all_phys(struct intel_dp
> >>> *intel_dp,
> >>>     }
> >>>
> >>>     if (ret)
> >>> -           intel_dp_link_train_phy(intel_dp, crtc_state,
> >>> DP_PHY_DPRX);
> >>> +           ret = intel_dp_link_train_phy(intel_dp, crtc_state,
> >>> DP_PHY_DPRX);
> >>>
> >>>     if (intel_dp->set_idle_link_train)
> >>>             intel_dp->set_idle_link_train(intel_dp, crtc_state);
> >>
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