From: David Laight <david.laight.linux@gmail.com>
To: James Clark <james.clark@linaro.org>
Cc: Frank Li <Frank.li@nxp.com>, Vladimir Oltean <olteanv@gmail.com>,
Mark Brown <broonie@kernel.org>,
Vladimir Oltean <vladimir.oltean@nxp.com>,
linux-spi@vger.kernel.org, imx@lists.linux.dev,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 2/4] spi: spi-fsl-dspi: Use non-coherent memory for DMA
Date: Fri, 13 Jun 2025 16:56:38 +0100 [thread overview]
Message-ID: <20250613165638.5d8ed000@pumpkin> (raw)
In-Reply-To: <d364667f-e0b1-4f1b-9034-2fadfd5d457b@linaro.org>
On Tue, 10 Jun 2025 16:46:36 +0100
James Clark <james.clark@linaro.org> wrote:
> On 10/06/2025 4:15 pm, Frank Li wrote:
> > On Mon, Jun 09, 2025 at 04:32:39PM +0100, James Clark wrote:
> >> Using coherent memory here isn't functionally necessary.
> >> Because the
> >> change to use non-coherent memory isn't overly complex and only a few
> >> synchronization points are required, we might as well do it while fixing
> >> up some other DMA issues.
> >
> > Any beanfit by use on-coherent memory here?
> >
> > Frank
> >
>
> Presumably less cache maintenance traffic?
I bet it only helps when cache-coherent memory has to be uncached.
Otherwise the software cache operations are pretty much guaranteed
to be more expensive than the hardware ones.
David
next prev parent reply other threads:[~2025-06-13 15:56 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-09 15:32 [PATCH 0/4] spi: spi-fsl-dspi: Target mode improvements James Clark
2025-06-09 15:32 ` [PATCH 1/4] spi: spi-fsl-dspi: Clear completion counter before initiating transfer James Clark
2025-06-10 11:34 ` Vladimir Oltean
2025-06-10 15:41 ` James Clark
2025-06-10 21:01 ` Vladimir Oltean
2025-06-10 21:31 ` Vladimir Oltean
2025-06-11 9:12 ` James Clark
2025-06-09 15:32 ` [PATCH 2/4] spi: spi-fsl-dspi: Use non-coherent memory for DMA James Clark
2025-06-10 8:26 ` Arnd Bergmann
2025-06-10 9:03 ` James Clark
2025-06-10 15:15 ` Frank Li
2025-06-10 15:46 ` James Clark
2025-06-13 15:56 ` David Laight [this message]
2025-06-10 15:48 ` Arnd Bergmann
2025-06-10 15:56 ` Frank Li
2025-06-11 9:01 ` Vladimir Oltean
2025-06-12 11:05 ` James Clark
2025-06-12 11:15 ` Vladimir Oltean
2025-06-12 14:14 ` James Clark
2025-06-12 14:23 ` Vladimir Oltean
2025-06-12 14:28 ` James Clark
2025-06-12 14:31 ` Vladimir Oltean
2025-06-12 14:35 ` James Clark
2025-06-12 14:36 ` Vladimir Oltean
2025-06-12 15:36 ` James Clark
2025-06-12 15:37 ` James Clark
2025-06-12 14:43 ` Mark Brown
2025-06-12 15:47 ` James Clark
2025-06-12 15:51 ` Vladimir Oltean
2025-06-12 15:40 ` Arnd Bergmann
2025-06-12 11:15 ` Arnd Bergmann
2025-06-09 15:32 ` [PATCH 3/4] spi: spi-fsl-dspi: Increase DMA buffer size James Clark
2025-06-09 15:32 ` [PATCH 4/4] spi: spi-fsl-dspi: Report FIFO overflows as errors James Clark
2025-06-10 21:52 ` Vladimir Oltean
2025-06-11 14:40 ` James Clark
2025-06-11 14:56 ` Vladimir Oltean
2025-06-11 15:00 ` James Clark
2025-06-30 11:40 ` [PATCH 0/4] spi: spi-fsl-dspi: Target mode improvements Mark Brown
2025-06-30 12:23 ` James Clark
2025-06-30 12:25 ` Mark Brown
2025-06-30 12:36 ` James Clark
2025-06-30 12:40 ` Mark Brown
2025-06-30 12:54 ` James Clark
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