From: Wolfram Sang <wsa@the-dreams.de>
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: linux-i2c@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Przemyslaw Sroka <psroka@cadence.com>,
Arkadiusz Golec <agolec@cadence.com>,
Alan Douglas <adouglas@cadence.com>,
Bartosz Folta <bfolta@cadence.com>, Damian Kos <dkos@cadence.com>,
Alicja Jurasik-Urbaniak <alicja@cadence.com>,
Cyprian Wronka <cwronka@cadence.com>,
Suresh Punnoose <sureshp@cadence.com>,
Rafal Ciepiela <rafalc@cadence.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Vitor Soares <Vitor.Soares@synopsys.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Linus Walleij <linus.walleij@linaro.org>,
Xiang Lin <Xiang.Lin@synaptics.com>,
linux-gpio@vger.kernel.org
Subject: Re: [PATCH v4 01/10] i3c: Add core I3C infrastructure
Date: Thu, 14 Jun 2018 13:19:42 +0900 [thread overview]
Message-ID: <20180614041941.4i2cadzoevujmzha@ninjato> (raw)
In-Reply-To: <20180330074751.25987-2-boris.brezillon@bootlin.com>
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Hi Boris,
> +/**
> + * struct i3c_priv_xfer - I3C SDR private transfer
> + * @rnw: encodes the transfer direction. true for a read, false for a write
> + * @len: transfer length in bytes of the transfer
> + * @data: input/output buffer
> + */
> +struct i3c_priv_xfer {
> + bool rnw;
> + u16 len;
> + union {
> + void *in;
> + const void *out;
> + } data;
So, this is probably where most payloads end up?
I didn't notice any sign of DMA in these patches, but given my
experiences, DMA will come sooner or later. And in I2C, this was
problematic because then a lot of drivers were in the wild getting their
buffers from everywhere (stack!). We now have an opt-in approach to mark
buffers as DMA-safe.
I don't know if typical I3C transfers will be similar to I2C with
usually small payloads where DMA usually makes not much sense. Yet, I
think, that it might be a good idea to think about how this shall be
handled with I3C right away. Maybe simply enforcing buffers to be
DMA-safe. Or whatever.
A clear rule on that might save you hazzle later.
Regards,
Wolfram
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next prev parent reply other threads:[~2018-06-14 4:19 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-30 7:47 [PATCH v4 00/10] Add the I3C subsystem Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 01/10] i3c: Add core I3C infrastructure Boris Brezillon
2018-06-04 9:11 ` Przemyslaw Gaj
2018-06-04 11:24 ` Boris Brezillon
2018-06-14 4:19 ` Wolfram Sang [this message]
2018-06-14 7:07 ` Boris Brezillon
2018-06-14 8:15 ` Wolfram Sang
2018-06-20 11:37 ` Sekhar Nori
2018-06-20 12:47 ` Boris Brezillon
2018-07-11 14:01 ` Arnd Bergmann
2018-07-11 14:41 ` Boris Brezillon
2018-07-11 15:03 ` Boris Brezillon
2018-07-11 15:39 ` Arnd Bergmann
2018-07-11 17:12 ` Boris Brezillon
2018-07-11 20:10 ` Arnd Bergmann
2018-07-11 22:09 ` Boris Brezillon
2018-07-12 8:21 ` Arnd Bergmann
2018-07-12 8:46 ` Boris Brezillon
2018-07-12 10:03 ` Arnd Bergmann
2018-07-12 10:24 ` Boris Brezillon
2018-07-12 4:41 ` Peter Rosin
2018-07-12 8:04 ` Boris Brezillon
2018-07-12 8:08 ` Arnd Bergmann
2018-07-12 8:44 ` Peter Rosin
2018-03-30 7:47 ` [PATCH v4 02/10] docs: driver-api: Add I3C documentation Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 03/10] i3c: Add sysfs ABI spec Boris Brezillon
2018-04-29 13:37 ` Greg Kroah-Hartman
2018-04-30 9:10 ` Boris Brezillon
2018-05-02 9:47 ` Geert Uytterhoeven
2018-05-02 11:10 ` Greg Kroah-Hartman
2018-05-02 11:32 ` Geert Uytterhoeven
2018-03-30 7:47 ` [PATCH v4 04/10] dt-bindings: i3c: Document core bindings Boris Brezillon
2018-03-30 7:55 ` Geert Uytterhoeven
2018-03-30 7:59 ` Boris Brezillon
2018-04-09 20:24 ` Rob Herring
2018-03-30 7:47 ` [PATCH v4 05/10] dt-bindings: i3c: Add macros to help fill I3C/I2C device's reg property Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 06/10] MAINTAINERS: Add myself as the I3C subsystem maintainer Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 07/10] i3c: master: Add driver for Cadence IP Boris Brezillon
2018-06-04 9:24 ` Przemyslaw Gaj
2018-06-04 11:26 ` Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 08/10] dt-bindings: i3c: Document Cadence I3C master bindings Boris Brezillon
2018-04-09 20:25 ` Rob Herring
2018-03-30 7:47 ` [PATCH v4 09/10] gpio: Add a driver for Cadence I3C GPIO expander Boris Brezillon
2018-04-26 8:44 ` Linus Walleij
2018-06-22 8:24 ` Boris Brezillon
2018-03-30 7:47 ` [PATCH v4 10/10] dt-bindings: gpio: Add bindings for Cadence I3C gpio expander Boris Brezillon
2018-04-09 20:26 ` Rob Herring
2018-04-23 17:38 ` [PATCH v4 00/10] Add the I3C subsystem Boris Brezillon
2018-04-23 17:56 ` Greg Kroah-Hartman
2018-04-29 13:36 ` Greg Kroah-Hartman
2018-04-30 9:37 ` Boris Brezillon
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