linux-kernel - Re: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders

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Message-ID: <6033a16ccbc6e1286b4bfd082f0de9f0d60594b7.camel@redhat.com>
Date:   Mon, 19 Nov 2018 13:51:53 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     "Zuo, Jerry" <Jerry.Zuo@....com>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>
Cc:     "Wentland, Harry" <Harry.Wentland@....com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        "Li, Roman" <Roman.Li@....com>, "S, Shirish" <Shirish.S@....com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders

Cool! If it did actually fix those problems, would you mind making sure this
gets Cc'd to stable when it gets pushed upstream?

On Mon, 2018-11-19 at 15:00 +0000, Zuo, Jerry wrote:
> Reviewed-by: Jerry (Fangzhi) Zuo <Jerry.Zuo@....com>
> 
> The change fixed MST + SST daisy chain and S3 scenarios. The issue shows
> huge delay in MST + SST daisy chain, and soft hang in S3 resume.
> 
> The aux sequence is changed by failed iteration search in
> drm_connector_for_each_possible_encoder(). 
> The failure of searching for the best encoder for the connector due to the
> miss of attached encoder in the process of adding MST connector. The
> iteration search takes time to push drm_dp_send_enum_path_resources() aux
> transaction after the mode probe, and causes conflict to
> drm_dp_mst_i2c_xfer(), leading to the aux transaction timeout.
> 
> -----Original Message-----
> From: Lyude Paul <lyude@...hat.com> 
> Sent: November 16, 2018 6:25 PM
> To: amd-gfx@...ts.freedesktop.org
> Cc: Zuo, Jerry <Jerry.Zuo@....com>; Wentland, Harry <Harry.Wentland@....com>
> ; Li, Sun peng (Leo) <Sunpeng.Li@....com>; Deucher, Alexander <
> Alexander.Deucher@....com>; Koenig, Christian <Christian.Koenig@....com>;
> Zhou, David(ChunMing) <David1.Zhou@....com>; David Airlie <airlied@...ux.ie>
> ; Li, Roman <Roman.Li@....com>; S, Shirish <Shirish.S@....com>; Daniel
> Vetter <daniel.vetter@...ll.ch>; dri-devel@...ts.freedesktop.org; 
> linux-kernel@...r.kernel.org
> Subject: [PATCH 1/2] drm/amd/dm: Don't forget to attach MST encoders
> 
> Drive-by fix, this is bound to cause problems somewhere.
> 
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> Cc: Jerry Zuo <Jerry.Zuo@....com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> index d02c32a1039c..0cca1809fdcd 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
> @@ -342,6 +342,8 @@ dm_dp_add_mst_connector(struct drm_dp_mst_topology_mgr
> *mgr,
>  		master->connector_id);
>  
>  	aconnector->mst_encoder = dm_dp_create_fake_mst_encoder(master);
> +	drm_connector_attach_encoder(&aconnector->base,
> +				     &aconnector->mst_encoder->base);
>  
>  	/*
>  	 * TODO: understand why this one is needed
-- 
Cheers,
	Lyude Paul