From: Mark Brown <broonie@kernel.org>
To: Lukas Wunner <lukas@wunner.de>
Cc: Vinod Koul <vkoul@kernel.org>, Stefan Wahren <wahrenst@gmx.net>,
linux-spi@vger.kernel.org, dmaengine@vger.kernel.org,
linux-rpi-kernel@lists.infradead.org,
bcm-kernel-feedback-list@broadcom.com,
Eric Anholt <eric@anholt.net>, Nuno Sa <nuno.sa@analog.com>,
Martin Sperl <kernel@martin.sperl.org>,
Noralf Tronnes <noralf@tronnes.org>,
Robert Jarzmik <robert.jarzmik@free.fr>,
Florian Kauer <florian.kauer@koalo.de>,
Florian Fainelli <f.fainelli@gmail.com>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>
Subject: Re: [PATCH 03/10] spi: Guarantee cacheline alignment of driver-private data
Date: Tue, 10 Sep 2019 12:29:23 +0100 [thread overview]
Message-ID: <20190910112923.GN2036@sirena.org.uk> (raw)
In-Reply-To: <69faaeb305582ab7dca65fa08635edfa1a39b3fa.1564825752.git.lukas@wunner.de>
[-- Attachment #1: Type: text/plain, Size: 724 bytes --]
On Sat, Aug 03, 2019 at 12:10:00PM +0200, Lukas Wunner wrote:
> __spi_alloc_controller() uses a single allocation to accommodate struct
>
> Reverse the order. A forthcoming commit leverages this to grant DMA
> access to driver-private data of the BCM2835 SPI master.
That's just shuffling the problem around, the same issues will
then apply to the controller struct and you'll take a performance
penalty on architectures that don't like unaligned accesses.
> An alternative approach would be to round up struct spi_controller to
> cacheline size, at the expense of some wasted memory.
That would seem more logical, or just do two alloacations. It's
not like we allocate huge numbers of SPI controllers.
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
next prev parent reply other threads:[~2019-09-10 11:29 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-03 10:10 [PATCH 00/10] Raspberry Pi SPI speedups Lukas Wunner
2019-08-03 10:10 ` [PATCH 01/10] dmaengine: bcm2835: Allow reusable descriptors Lukas Wunner
2019-08-08 12:30 ` Vinod Koul
2019-08-03 10:10 ` [PATCH 04/10] spi: bcm2835: Drop dma_pending flag Lukas Wunner
2019-08-03 10:10 ` [PATCH 05/10] spi: bcm2835: Work around DONE bit erratum Lukas Wunner
2019-08-11 19:45 ` Stefan Wahren
2019-08-11 19:57 ` Lukas Wunner
2019-08-11 20:29 ` Eric Anholt
2019-08-19 19:20 ` Stefan Wahren
2019-08-03 10:10 ` [PATCH 09/10] dmaengine: bcm2835: Avoid accessing memory when copying zeroes Lukas Wunner
2019-08-08 12:31 ` Vinod Koul
2019-08-03 10:10 ` [PATCH 07/10] spi: bcm2835: Speed up TX-only DMA transfers by clearing RX FIFO Lukas Wunner
2019-08-03 10:10 ` [PATCH 06/10] spi: bcm2835: Cache CS register value for ->prepare_message() Lukas Wunner
2019-08-03 10:10 ` [PATCH 02/10] dmaengine: bcm2835: Allow cyclic transactions without interrupt Lukas Wunner
2019-08-08 12:30 ` Vinod Koul
2019-08-03 10:10 ` [PATCH 08/10] dmaengine: bcm2835: Document struct bcm2835_dmadev Lukas Wunner
2019-08-08 12:31 ` Vinod Koul
2019-08-03 10:10 ` [PATCH 10/10] spi: bcm2835: Speed up RX-only DMA transfers by zero-filling TX FIFO Lukas Wunner
2019-08-03 10:10 ` [PATCH 03/10] spi: Guarantee cacheline alignment of driver-private data Lukas Wunner
2019-09-10 11:29 ` Mark Brown [this message]
2019-08-03 16:01 ` [PATCH 00/10] Raspberry Pi SPI speedups Noralf Trønnes
2019-08-11 19:50 ` Stefan Wahren
2019-08-11 19:52 ` Lukas Wunner
2019-08-19 19:22 ` Stefan Wahren
2019-08-21 15:21 ` kernel
2019-08-24 10:33 ` Lukas Wunner
2019-09-07 9:06 ` Lukas Wunner
2019-09-09 16:56 ` Mark Brown
2019-09-10 11:21 ` Mark Brown
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190910112923.GN2036@sirena.org.uk \
--to=broonie@kernel.org \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=dmaengine@vger.kernel.org \
--cc=eric@anholt.net \
--cc=f.fainelli@gmail.com \
--cc=florian.kauer@koalo.de \
--cc=kernel@martin.sperl.org \
--cc=linux-rpi-kernel@lists.infradead.org \
--cc=linux-spi@vger.kernel.org \
--cc=lukas@wunner.de \
--cc=noralf@tronnes.org \
--cc=nuno.sa@analog.com \
--cc=rjui@broadcom.com \
--cc=robert.jarzmik@free.fr \
--cc=sbranden@broadcom.com \
--cc=vkoul@kernel.org \
--cc=wahrenst@gmx.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.