Messages in this thread | | | Date | Thu, 27 Jan 2022 00:18:10 -0800 | From | Lucas De Marchi <> | Subject | Re: [Intel-gfx] [PATCH 02/19] dma-buf-map: Add helper to initialize second map |
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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
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