From: Lucas De Marchi <lucas.demarchi@intel.com>
To: "Christian König" <christian.koenig@amd.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
Subject: Re: [Intel-gfx] [PATCH 02/19] dma-buf-map: Add helper to initialize second map
Date: Thu, 27 Jan 2022 00:18:10 -0800 [thread overview]
Message-ID: <20220127081810.6zt6cyib4s7kpa6f@ldmartin-desk2> (raw)
In-Reply-To: <3066c6a7-fc73-d34d-d209-a3ff6818dfb6@amd.com>
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:
>>>>When dma_buf_map struct is passed around, it's useful to be able to
>>>>initialize a second map that takes care of reading/writing to an offset
>>>>of the original map.
>>>>
>>>>Add a helper that copies the struct and add the offset to the proper
>>>>address.
>>>
>>>Well what you propose here can lead to all kind of problems and is
>>>rather bad design as far as I can see.
>>>
>>>The struct dma_buf_map is only to be filled in by the exporter and
>>>should not be modified in this way by the importer.
>>
>>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.
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.
Lucas De Marchi
next prev parent reply other threads:[~2022-01-27 8:18 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 ` Lucas De Marchi [this message]
2022-01-27 8:55 ` [Intel-gfx] " Christian König
2022-01-27 9:12 ` Lucas De Marchi
2022-01-27 9:21 ` Christian König
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220127081810.6zt6cyib4s7kpa6f@ldmartin-desk2 \
--to=lucas.demarchi@intel.com \
--cc=christian.koenig@amd.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).