From: "Christian König" <christian.koenig@amd.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: linaro-mm-sig@lists.linaro.org, intel-gfx@lists.freedesktop.org,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-media@vger.kernel.org,
Thomas Zimmermann <tzimmermann@suse.de>
Subject: Re: [Intel-gfx] [PATCH 02/19] dma-buf-map: Add helper to initialize second map
Date: Thu, 27 Jan 2022 10:21:53 +0100 [thread overview]
Message-ID: <69c260e4-f4b8-e51c-4930-e7aaf9bec2b9@amd.com> (raw)
In-Reply-To: <20220127091247.3uqi5zhesqtecbsw@ldmartin-desk2>
Am 27.01.22 um 10:12 schrieb Lucas De Marchi:
> On Thu, Jan 27, 2022 at 09:55:05AM +0100, Christian König wrote:
>> Am 27.01.22 um 09:18 schrieb Lucas De Marchi:
>>> On Thu, Jan 27, 2022 at 09:02:54AM +0100, Christian König wrote:
>>>> Am 27.01.22 um 08:57 schrieb Lucas De Marchi:
>>>>> On Thu, Jan 27, 2022 at 08:27:11AM +0100, Christian König wrote:
>>>>>> Am 26.01.22 um 21:36 schrieb Lucas De Marchi:
>>>>>>> [SNIP]
>>>>> humn... not sure if I was clear. There is no importer and
>>>>> exporter here.
>>>>
>>>> Yeah, and exactly that's what I'm pointing out as problem here.
>>>>
>>>> You are using the inter driver framework for something internal to
>>>> the driver. That is an absolutely clear NAK!
>>>>
>>>> We could discuss that, but you guys are just sending around patches
>>>> to do this without any consensus that this is a good idea.
>>>
>>> s/you guys/you/ if you have to blame anyone - I'm the only s-o-b in
>>> these patches. I'm sending these to _build consensus_ on what may be
>>> a good
>>> use for it showing a real problem it's helping to fix.
>>
>> Well a cover letter would have been helpful, my impression was that
>> you have a larger set and just want to upstream some minor DMA-buf
>> changes necessary for it.
>
> I missed adding this sentence to the cover letter, as my impression
> was that
> dma-buf-map was already used outside inter-driver framework. But there
> is actually a cover letter:
>
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fall%2F20220126203702.1784589-1-lucas.demarchi%40intel.com%2F&data=04%7C01%7Cchristian.koenig%40amd.com%7Cb36def4a6ebd4879731c08d9e1753ccd%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637788715933199161%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=gwW05OaUq%2FxlBWnY%2FPuPfl0YDdKp5VTbllaSmn45nE8%3D&reserved=0
>
>
> And looking at it now, it seems I missed adding Thomas Zimmermann to Cc.
>
>>
>> Now I know why people are bugging me all the time to add cover
>> letters to add more context to my sets.
>>
>>>
>>> From its documentation:
>>>
>>> * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its
>>> helpers are
>>> * actually independent from the dma-buf infrastructure. When
>>> sharing buffers
>>> * among devices, drivers have to know the location of the memory to
>>> access
>>> * the buffers in a safe way. :c:type:`struct dma_buf_map
>>> <dma_buf_map>`
>>> * solves this problem for dma-buf and its users. If other drivers or
>>> * sub-systems require similar functionality, the type could be
>>> generalized
>>> * and moved to a more prominent header file.
>>>
>>> if there is no consensus and a better alternative, I'm perfectly
>>> fine in
>>> throwing it out and using the better approach.
>>
>> When Thomas Zimmermann upstreamed the dma_buf_map work we had a
>> discussion if that shouldn't be independent of the DMA-buf framework.
>>
>> The consensus was that as soon as we have more widely use for it this
>> should be made independent. So basically that is what's happening now.
>>
>> I suggest the following approach:
>> 1. Find a funky name for this, something like iomem_, kiomap_ or
>> similar.
>
> iosys_map?
Works for me.
>
>> 2. Separate this from all you driver dependent work and move the
>> dma_buf_map structure out of DMA-buf into this new whatever_ prefix.
>
> should this be a follow up to the driver work or a prerequisite?
Prerequisite. Structural changes like this always separate to the
actually work switching over to them because the later needs a much
fewer audience for review.
Regards,
Christian.
>
> thanks
> Lucas De Marchi
>
>> 3. Ping Thomas, LKML, me and probably a couple of other core people
>> if this is the right idea or not.
>> 4. Work on dropping the map parameter from dma_buf_vunmap(). This is
>> basically why we can't modify the pointers returned from
>> dma_buf_vmap() and has already cause a few problems with
>> dma_buf_map_incr().
>>
>> Regards,
>> Christian.
>>
>>>
>>> Lucas De Marchi
>>
next prev parent reply other threads:[~2022-01-27 9:22 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 20:36 [PATCH 00/19] drm/i915/guc: Refactor ADS access to use dma_buf_map Lucas De Marchi
2022-01-26 20:36 ` [PATCH 01/19] dma-buf-map: Add read/write helpers Lucas De Marchi
2022-01-27 7:24 ` Christian König
2022-01-27 7:36 ` Matthew Brost
2022-01-27 7:59 ` Christian König
2022-01-27 9:02 ` [Intel-gfx] " Daniel Vetter
2022-01-27 14:26 ` Thomas Zimmermann
2022-01-27 16:34 ` Lucas De Marchi
2022-01-28 8:32 ` Thomas Zimmermann
2022-01-26 20:36 ` [PATCH 02/19] dma-buf-map: Add helper to initialize second map Lucas De Marchi
2022-01-27 7:27 ` Christian König
2022-01-27 7:57 ` Lucas De Marchi
2022-01-27 8:02 ` Christian König
2022-01-27 8:18 ` [Intel-gfx] " Lucas De Marchi
2022-01-27 8:55 ` Christian König
2022-01-27 9:12 ` Lucas De Marchi
2022-01-27 9:21 ` Christian König [this message]
2022-01-27 8:57 ` Daniel Vetter
2022-01-27 9:33 ` [Intel-gfx] " Lucas De Marchi
2022-01-27 10:00 ` Daniel Vetter
2022-01-27 10:21 ` Christian König
2022-01-27 11:16 ` Daniel Vetter
2022-01-27 11:44 ` [Linaro-mm-sig] " Christian König
2022-01-27 11:56 ` Daniel Vetter
2022-01-27 16:13 ` Lucas De Marchi
2022-01-27 14:52 ` Thomas Zimmermann
2022-01-27 16:12 ` Lucas De Marchi
2022-01-27 14:33 ` Thomas Zimmermann
2022-01-27 15:59 ` [Intel-gfx] " Lucas De Marchi
2022-01-28 8:15 ` Thomas Zimmermann
2022-01-28 8:34 ` Thomas Zimmermann
2022-01-26 20:36 ` [PATCH 09/19] dma-buf-map: Add wrapper over memset Lucas De Marchi
2022-01-27 7:28 ` Christian König
2022-01-27 14:54 ` Thomas Zimmermann
2022-01-27 15:38 ` [Intel-gfx] " Lucas De Marchi
2022-01-27 15:47 ` Thomas Zimmermann
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