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From: Christoph Hellwig <hch@lst.de>
To: Mark Brown <broonie@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	James Clark <james.clark@linaro.org>,
	olteanv@gmail.com, oe-kbuild-all@lists.linux.dev, arnd@arndb.de,
	larisa.grigore@nxp.com, Frank.li@nxp.com,
	linux-spi@vger.kernel.org, imx@lists.linux.dev,
	linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	iommu@lists.linux.dev
Subject: Re: [PATCH] dma-mapping: Stub out dma_{alloc,free,map}_pages() API
Date: Mon, 16 Jun 2025 14:08:32 +0200	[thread overview]
Message-ID: <20250616120832.GA24959@lst.de> (raw)
In-Reply-To: <5f1ca0ac-b66c-4b92-8f69-027c2468b117@sirena.org.uk>

On Mon, Jun 16, 2025 at 01:06:00PM +0100, Mark Brown wrote:
> On Mon, Jun 16, 2025 at 01:29:27PM +0200, Christoph Hellwig wrote:
> > On Mon, Jun 16, 2025 at 12:17:49PM +0100, James Clark wrote:
> 
> > > The implementations are in mapping.c which requires HAS_DMA so stub them
> > > out if not present. This is required for some drivers to pass randconfig
> > > builds.
> 
> > No.  Just add the proper IS_ENABLED checks in the callers.  While these
> > kinds of stubs used to be popular they are really nasty in that the
> > calls unexpectedly just fail without the right depends.
> 
> The issue with HAS_DMA is that essentially all platforms have and rely
> on DMA.  This ends up just being painful noise from the buildbots when
> they do randconfigs rather than something useful.

In most case the driver really does depend on DMA to work, so just
depend on HAS_DMA.  If it can work without DMA, you can use IS_ENABLED.


  reply	other threads:[~2025-06-16 12:08 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-13  9:28 [PATCH v2 0/5] spi: spi-fsl-dspi: Target mode improvements James Clark
2025-06-13  9:28 ` [PATCH v2 1/5] spi: spi-fsl-dspi: Clear completion counter before initiating transfer James Clark
2025-06-13  9:28 ` [PATCH v2 2/5] spi: spi-fsl-dspi: Use non-coherent memory for DMA James Clark
2025-06-15 16:31   ` kernel test robot
2025-06-16 11:17     ` [PATCH] dma-mapping: Stub out dma_{alloc,free,map}_pages() API James Clark
2025-06-16 11:21       ` James Clark
2025-06-16 11:28       ` Arnd Bergmann
2025-06-16 11:29       ` Christoph Hellwig
2025-06-16 12:06         ` Mark Brown
2025-06-16 12:08           ` Christoph Hellwig [this message]
2025-06-16 12:11             ` Mark Brown
2025-06-16 12:14               ` Christoph Hellwig
2025-06-16 13:05                 ` Mark Brown
2025-06-16 13:12                   ` Christoph Hellwig
2025-06-16 13:10                 ` James Clark
2025-06-16 13:13                   ` Christoph Hellwig
2025-06-16 13:14                     ` James Clark
2025-06-16 13:15                       ` James Clark
2025-06-16 13:19                         ` Christoph Hellwig
2025-06-16 13:23                           ` James Clark
2025-06-16 13:48                             ` Arnd Bergmann
2025-06-16 18:33                               ` Arnd Bergmann
2025-06-17  4:48                               ` Christoph Hellwig
2025-06-17  7:53                                 ` Arnd Bergmann
2025-06-17  8:26                                   ` Arnd Bergmann
2025-06-17 15:55                                     ` Jason Gunthorpe
2025-06-16 11:56   ` [PATCH v2 2/5] spi: spi-fsl-dspi: Use non-coherent memory for DMA Robin Murphy
2025-06-16 13:06     ` James Clark
2025-06-13  9:28 ` [PATCH v2 3/5] spi: spi-fsl-dspi: Increase DMA buffer size James Clark
2025-06-13  9:28 ` [PATCH v2 4/5] spi: spi-fsl-dspi: Store status directly in cur_msg->status James Clark
2025-06-13  9:29 ` [PATCH v2 5/5] spi: spi-fsl-dspi: Report FIFO overflows as errors James Clark

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