Re: [PATCH v3 05/12] drm/ttm: Expose ttm_tt_unpopulate for driver use

From: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
To: christian.koenig@amd.com, amd-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch,
	robh@kernel.org, l.stach@pengutronix.de, yuq825@gmail.com,
	eric@anholt.net
Cc: Alexander.Deucher@amd.com, gregkh@linuxfoundation.org,
	ppaalanen@gmail.com, Harry.Wentland@amd.com
Subject: Re: [PATCH v3 05/12] drm/ttm: Expose ttm_tt_unpopulate for driver use
Date: Mon, 23 Nov 2020 15:38:19 -0500	[thread overview]
Message-ID: <e2f4f1dc-2a2a-face-87b2-6d61ed7d3305@amd.com> (raw)
In-Reply-To: <41b35672-2dd6-13e2-8383-c65279fdb648@gmail.com>

On 11/23/20 3:20 PM, Christian König wrote:
> Am 23.11.20 um 21:05 schrieb Andrey Grodzovsky:
>>
>> On 11/25/20 5:42 AM, Christian König wrote:
>>> Am 21.11.20 um 06:21 schrieb Andrey Grodzovsky:
>>>> It's needed to drop iommu backed pages on device unplug
>>>> before device's IOMMU group is released.
>>>
>>> It would be cleaner if we could do the whole handling in TTM. I also need to 
>>> double check what you are doing with this function.
>>>
>>> Christian.
>>
>>
>> Check patch "drm/amdgpu: Register IOMMU topology notifier per device." to see
>> how i use it. I don't see why this should go into TTM mid-layer - the stuff I 
>> do inside
>> is vendor specific and also I don't think TTM is explicitly aware of IOMMU ?
>> Do you mean you prefer the IOMMU notifier to be registered from within TTM
>> and then use a hook to call into vendor specific handler ?
>
> No, that is really vendor specific.
>
> What I meant is to have a function like ttm_resource_manager_evict_all() which 
> you only need to call and all tt objects are unpopulated.

So instead of this BO list i create and later iterate in amdgpu from the IOMMU 
patch you just want to do it within
TTM with a single function ? Makes much more sense.

Andrey

>
> Give me a day or two to look into this.
>
> Christian.
>
>>
>> Andrey
>>
>>
>>>
>>>>
>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>>> ---
>>>>   drivers/gpu/drm/ttm/ttm_tt.c | 1 +
>>>>   1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
>>>> index 1ccf1ef..29248a5 100644
>>>> --- a/drivers/gpu/drm/ttm/ttm_tt.c
>>>> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
>>>> @@ -495,3 +495,4 @@ void ttm_tt_unpopulate(struct ttm_tt *ttm)
>>>>       else
>>>>           ttm_pool_unpopulate(ttm);
>>>>   }
>>>> +EXPORT_SYMBOL(ttm_tt_unpopulate);
>>>
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