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

[Almahallawy, Khaled]

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
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);