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Date:   Wed, 10 Aug 2022 09:23:50 -0400
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Subject: Re: [PATCH v2 1/3] drm/dp_mst: add passthrough_aux to struct
 drm_dp_mst_port
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To:     Lyude Paul <lyude@redhat.com>, linux-kernel@vger.kernel.org
Cc:     Harry Wentland <harry.wentland@amd.com>,
        Fangzhi Zuo <Jerry.Zuo@amd.com>, Wayne Lin <Wayne.Lin@amd.com>,
        Aurabindo Pillai <aurabindo.pillai@amd.com>,
        hersenxs.wu@amd.com, Leo Li <sunpeng.li@amd.com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Mikita Lipski <mikita.lipski@amd.com>,
        Claudio Suarez <cssk@net-c.es>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>,
        Roman Li <Roman.Li@amd.com>, Ian Chen <ian.chen@amd.com>,
        Colin Ian King <colin.king@intel.com>,
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        Imran Khan <imran.f.khan@oracle.com>,
        =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>,
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        Kees Cook <keescook@chromium.org>,
        Imre Deak <imre.deak@intel.com>,
        David Zhang <dingchen.zhang@amd.com>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
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From:   Hamza Mahfooz <hamza.mahfooz@amd.com>
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On 2022-08-09 18:01, Lyude Paul wrote:
> Ah yes of course! Probably should have asked when I gave the r-b :). Also,
> just so patchwork actually catches it I will say the magic incantation:
> 
> Reviewed-by: Lyude Paul <lyude@redhat.com>
> 
> Do we want to merge just this patch to drm-misc-next, or do you want to merge
> the whole series through there? If you'd rather just merge this through amd's
> branch I'm fine with that as well

In that case, it is preferable to have all of the patches in this series
to get merged through amd's branch.

> 
> On Tue, 2022-08-09 at 11:15 -0400, Hamza Mahfooz wrote:
>> Hey Lyude,
>>
>> On 2022-08-05 17:17, Lyude Paul wrote:
>>> lgtm!
>>>
>>
>> Any chance you can apply this to drm-misc-next?
>>
>>> Reviewed-by: Lyude Paul <lyude@redhat.com>
>>>
>>> On Fri, 2022-08-05 at 17:13 -0400, Hamza Mahfooz wrote:
>>>> Currently, there is no way to identify if DSC pass-through can be
>>>> enabled and what aux DSC pass-through requests ought to be sent to. So,
>>>> add a variable to struct drm_dp_mst_port that keeps track of the
>>>> aforementioned information.
>>>>
>>>> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
>>>> ---
>>>> v2: define DP_DSC_PASSTHROUGH_IS_SUPPORTED
>>>> ---
>>>>    drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++-
>>>>    include/drm/display/drm_dp.h                  | 1 +
>>>>    include/drm/display/drm_dp_mst_helper.h       | 3 +++
>>>>    3 files changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>>>> index 67b3b9697da7..71915afd9892 100644
>>>> --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
>>>> +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
>>>> @@ -5921,8 +5921,10 @@ struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
>>>>    		/* Enpoint decompression with DP-to-DP peer device */
>>>>    		if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
>>>>    		    (endpoint_fec & DP_FEC_CAPABLE) &&
>>>> -		    (upstream_dsc & 0x2) /* DSC passthrough */)
>>>> +		    (upstream_dsc & DP_DSC_PASSTHROUGH_IS_SUPPORTED)) {
>>>> +			port->passthrough_aux = &immediate_upstream_port->aux;
>>>>    			return &port->aux;
>>>> +		}
>>>>    
>>>>    		/* Virtual DPCD decompression with DP-to-DP peer device */
>>>>    		return &immediate_upstream_port->aux;
>>>> diff --git a/include/drm/display/drm_dp.h b/include/drm/display/drm_dp.h
>>>> index 9e3aff7e68bb..4d0abe4c7ea9 100644
>>>> --- a/include/drm/display/drm_dp.h
>>>> +++ b/include/drm/display/drm_dp.h
>>>> @@ -239,6 +239,7 @@
>>>>    
>>>>    #define DP_DSC_SUPPORT                      0x060   /* DP 1.4 */
>>>>    # define DP_DSC_DECOMPRESSION_IS_SUPPORTED  (1 << 0)
>>>> +# define DP_DSC_PASSTHROUGH_IS_SUPPORTED    (1 << 1)
>>>>    
>>>>    #define DP_DSC_REV                          0x061
>>>>    # define DP_DSC_MAJOR_MASK                  (0xf << 0)
>>>> diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
>>>> index 10adec068b7f..4a39c95f8afd 100644
>>>> --- a/include/drm/display/drm_dp_mst_helper.h
>>>> +++ b/include/drm/display/drm_dp_mst_helper.h
>>>> @@ -86,6 +86,8 @@ struct drm_dp_vcpi {
>>>>     * @next: link to next port on this branch device
>>>>     * @aux: i2c aux transport to talk to device connected to this port, protected
>>>>     * by &drm_dp_mst_topology_mgr.base.lock.
>>>> + * @passthrough_aux: parent aux to which DSC pass-through requests should be
>>>> + * sent, only set if DSC pass-through is possible.
>>>>     * @parent: branch device parent of this port
>>>>     * @vcpi: Virtual Channel Payload info for this port.
>>>>     * @connector: DRM connector this port is connected to. Protected by
>>>> @@ -140,6 +142,7 @@ struct drm_dp_mst_port {
>>>>    	 */
>>>>    	struct drm_dp_mst_branch *mstb;
>>>>    	struct drm_dp_aux aux; /* i2c bus for this port? */
>>>> +	struct drm_dp_aux *passthrough_aux;
>>>>    	struct drm_dp_mst_branch *parent;
>>>>    
>>>>    	struct drm_dp_vcpi vcpi;
>>>
>>
> 

-- 
Hamza