linux-kernel - Re: [PATCHv4 1/8] videobuf2: rework vb2_mem

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Message-ID: <YRuSQMTcexYmFGub@google.com>
Date:   Tue, 17 Aug 2021 19:41:04 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Dafna Hirschfeld <dafna.hirschfeld@...labora.com>,
        Ricardo Ribalda <ribalda@...omium.org>,
        Christoph Hellwig <hch@....de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 1/8] videobuf2: rework vb2_mem_ops API

On (21/08/03 10:08), Hans Verkuil wrote:
> On 27/07/2021 09:05, Sergey Senozhatsky wrote:
> 
> Sprinkle a few more 'the's in the text:
> 
> > With new DMA API we need an extension of videobuf2 API. Previously,
> 
> With -> With the
> of -> of the
> 
> > videobuf2 core would set non-coherent DMA bit in vb2 queue dma_attr
> 
> videobuf2 -> the videobuf2
> set -> set the
> in vb2 queue dma_attr -> in the vb2_queue dma_attr field
> 
> > (if user-space would pass a corresponding memory hint); vb2 core
> 
> vb2 core -> the vb2 core
> 
> > then would pass the vb2 queue dma_attrs to the vb2 allocators.
> 
> vb2 queue -> vb2_queue
> 
> > vb2 allocator would use queue's dma_attr and DMA API would allocate
> 
> vb2 -> The vb2
> queue's -> the queue's
> DMA API -> the DMA API
> 
> > either coherent or non-coherent memory.
> > 
> > But we cannot do this anymore, since there is no corresponding DMA
> > attr flag and, hence, there is no way for the allocator to become
> > aware of what type of allocation user-space has requested. So we
> > need to pass more context from videobuf2 core to the allocators.
> > 
> > Fix this by changing call_ptr_memop() macro to pass vb2 pointer to
> 
> changing -> changing the
> vb2 pointer to -> the vb2 pointer to the

Ack... The Ack.