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Date: Wed, 31 Jan 2024 17:52:58 +0100
From: Simon Horman <horms@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Christoph Hellwig <hch@lst.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>, Joerg Roedel <joro@8bytes.org>,
	Will Deacon <will@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Magnus Karlsson <magnus.karlsson@intel.com>,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	Alexander Duyck <alexanderduyck@fb.com>, bpf@vger.kernel.org,
	netdev@vger.kernel.org, iommu@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 1/7] dma: compile-out DMA sync op calls when not
 used
Message-ID: <20240131165258.GA401365@kernel.org>
References: <20240126135456.704351-1-aleksander.lobakin@intel.com>
 <20240126135456.704351-2-aleksander.lobakin@intel.com>
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In-Reply-To: <20240126135456.704351-2-aleksander.lobakin@intel.com>

On Fri, Jan 26, 2024 at 02:54:50PM +0100, Alexander Lobakin wrote:
> Some platforms do have DMA, but DMA there is always direct and coherent.
> Currently, even on such platforms DMA sync operations are compiled and
> called.
> Add a new hidden Kconfig symbol, DMA_NEED_SYNC, and set it only when
> either sync operations are needed or there is DMA ops or swiotlb
> enabled. Set dma_need_sync() and dma_skip_sync() (stub for now)
> depending on this symbol state and don't call sync ops when
> dma_skip_sync() is true.
> The change allows for future optimizations of DMA sync calls depending
> on compile-time or runtime conditions.
> 
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>

Hi Alexander,

This seems to cause x86_64 allmodconfig builds to fail:

 ../drivers/media/platform/ti/omap3isp/ispstat.c:82:35: error: ‘dma_sync_single_range_for_device’ undeclared (first use in this function); did you mean ‘dma_sync_sgtable_for_device’?
    82 |                                   dma_sync_single_range_for_device);
       |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       |                                   dma_sync_sgtable_for_device
 ../drivers/media/platform/ti/omap3isp/ispstat.c:82:35: note: each undeclared identifier is reported only once for each function it appears in
 ../drivers/media/platform/ti/omap3isp/ispstat.c: In function ‘isp_stat_buf_sync_magic_for_cpu’:
 ../drivers/media/platform/ti/omap3isp/ispstat.c:94:35: error: ‘dma_sync_single_range_for_cpu’ undeclared (first use in this function); did you mean ‘dma_sync_sgtable_for_cpu’?
    94 |                                   dma_sync_single_range_for_cpu);
       |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       |                                   dma_sync_sgtable_for_cpu