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Subject: Re: [PATCH net-next 5/9] page_pool: don't use driver-set flags field
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To:     Alexander Lobakin <aleksander.lobakin@intel.com>
CC:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
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        Alexander Duyck <alexanderduyck@fb.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Simon Horman <simon.horman@corigine.com>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
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From:   Yunsheng Lin <linyunsheng@huawei.com>
Message-ID: <03124fbf-1b47-99e1-d9a5-a9251890f6e7@huawei.com>
Date:   Wed, 2 Aug 2023 19:36:17 +0800
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On 2023/8/1 21:36, Alexander Lobakin wrote:

>>
>> It just seems odd to me that dma_map and page_frag is duplicated as we
>> seems to have the same info in the page_pool->p.flags.
> 
> It's just because we copy the whole &page_pool_params passed by the
> driver. It doesn't look good to me to define a new structure and copy
> the values field-by-field just to avoid duplicating 3 bits :s
> 
>>
>> What about:
>> In [PATCH net-next 4/9] page_pool: shrink &page_pool_params a tiny bit,
>> 'flags' is bit-field'ed with 'dma_dir', what about changing 'dma_dir'
>> to be bit-field'ed with 'dma_sync_act', so that page_pool->p.flags stays
>> the same as before, and 'dma_map' & 'page_frag' do not seems be really
>> needed as we have the same info in page_pool->p.flags?
> 
> Not sure I follow :z ::dma_dir is also passed by the driver, so we can't
> drop it from the params struct.

My bad, I missed that dma_dir is in the params struct.