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Message-ID: <4d2678be-e36c-4726-83a5-ae9a3a0def55@intel.com>
Date: Mon, 19 Feb 2024 13:49:10 +0100
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Robin Murphy <robin.murphy@....com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, Christoph Hellwig <hch@....de>, Marek Szyprowski
<m.szyprowski@...sung.com>, Joerg Roedel <joro@...tes.org>, Will Deacon
<will@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael
J. Wysocki" <rafael@...nel.org>, Magnus Karlsson <magnus.karlsson@...el.com>,
Maciej Fijalkowski <maciej.fijalkowski@...el.com>, Alexander Duyck
<alexanderduyck@...com>, <bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
<iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v3 2/7] dma: avoid redundant calls for sync
operations
From: Robin Murphy <robin.murphy@....com>
Date: Wed, 14 Feb 2024 17:55:23 +0000
> On 2024-02-14 4:21 pm, Alexander Lobakin wrote:
[...]
>> + /*
>> + * Synchronization is not possible when none of DMA sync ops
>> + * is set. This check precedes the below one as it disables
>> + * the synchronization unconditionally.
>> + */
>> + dev->dma_skip_sync = true;
>> + else if (ops->flags & DMA_F_CAN_SKIP_SYNC)
>
> Personally I'd combine this into the dma-direct condition.
Please read the code comment a couple lines above :D
>
>> + /*
>> + * Assume that when ``DMA_F_CAN_SKIP_SYNC`` is advertised,
>> + * the conditions for synchronizing are the same as with
>> + * the direct DMA.
>> + */
>> + dev->dma_skip_sync = dev_is_dma_coherent(dev);
>> + else
>> + dev->dma_skip_sync = false;
>> +}
>> +#endif /* CONFIG_DMA_NEED_SYNC */
[...]
Thanks,
Olek
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