From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Jiada Wang <jiada_wang@mentor.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Mark Rutland <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
Sascha Hauer <kernel@pengutronix.de>,
Fabio Estevam <fabio.estevam@nxp.com>,
Shawn Guo <shawnguo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH RFC 0/5] *** SPI Slave mode support ***
Date: Tue, 25 Apr 2017 10:07:38 +0200 [thread overview]
Message-ID: <20170425080738.cb6jaqvktgpir7zq@pengutronix.de> (raw)
In-Reply-To: <58FF0127.7070703@mentor.com>
Hello Jiada,
On Tue, Apr 25, 2017 at 12:56:23AM -0700, Jiada Wang wrote:
> the use case of
> "A (master) <=> B (slave)", "B (master) <=> C(slave)", do share MISO and
> MOSI lines,
> but there is no SS line between A and C. so for each SPI slave device, there
> is only one
> master device.
So you need a mutex to make A not use the bus while B communicates to C.
Otherwise you have two drivers on MOSI (A and B) and MISO (B and C).
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
WARNING: multiple messages have this Message-ID (diff)
From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Jiada Wang <jiada_wang@mentor.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Sascha Hauer <kernel@pengutronix.de>,
Fabio Estevam <fabio.estevam@nxp.com>,
Shawn Guo <shawnguo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH RFC 0/5] *** SPI Slave mode support ***
Date: Tue, 25 Apr 2017 10:07:38 +0200 [thread overview]
Message-ID: <20170425080738.cb6jaqvktgpir7zq@pengutronix.de> (raw)
In-Reply-To: <58FF0127.7070703@mentor.com>
Hello Jiada,
On Tue, Apr 25, 2017 at 12:56:23AM -0700, Jiada Wang wrote:
> the use case of
> "A (master) <=> B (slave)", "B (master) <=> C(slave)", do share MISO and
> MOSI lines,
> but there is no SS line between A and C. so for each SPI slave device, there
> is only one
> master device.
So you need a mutex to make A not use the bus while B communicates to C.
Otherwise you have two drivers on MOSI (A and B) and MISO (B and C).
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
WARNING: multiple messages have this Message-ID (diff)
From: u.kleine-koenig@pengutronix.de (Uwe Kleine-König)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC 0/5] *** SPI Slave mode support ***
Date: Tue, 25 Apr 2017 10:07:38 +0200 [thread overview]
Message-ID: <20170425080738.cb6jaqvktgpir7zq@pengutronix.de> (raw)
In-Reply-To: <58FF0127.7070703@mentor.com>
Hello Jiada,
On Tue, Apr 25, 2017 at 12:56:23AM -0700, Jiada Wang wrote:
> the use case of
> "A (master) <=> B (slave)", "B (master) <=> C(slave)", do share MISO and
> MOSI lines,
> but there is no SS line between A and C. so for each SPI slave device, there
> is only one
> master device.
So you need a mutex to make A not use the bus while B communicates to C.
Otherwise you have two drivers on MOSI (A and B) and MISO (B and C).
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
next prev parent reply other threads:[~2017-04-25 8:11 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 12:13 [PATCH RFC 0/5] *** SPI Slave mode support *** jiada_wang
2017-04-13 12:13 ` jiada_wang at mentor.com
2017-04-13 12:13 ` jiada_wang
2017-04-13 12:13 ` jiada_wang
2017-04-13 12:14 ` [PATCH RFC 1/5] spi: core: add support to work in Slave mode jiada_wang
2017-04-13 12:14 ` jiada_wang at mentor.com
2017-04-13 12:14 ` jiada_wang-nmGgyN9QBj3QT0dZR+AlfA
2017-04-13 12:14 ` jiada_wang-nmGgyN9QBj3QT0dZR+AlfA
2017-04-13 12:14 ` [PATCH RFC 2/5] spi: spidev: use different name for SPI controller slave mode device jiada_wang
2017-04-13 12:14 ` jiada_wang at mentor.com
2017-04-13 12:14 ` jiada_wang
2017-04-13 12:14 ` jiada_wang
2017-04-13 12:14 ` [PATCH RFC 3/5] spi: imx: add selection for iMX53 and iMX6 controller jiada_wang
2017-04-13 12:14 ` jiada_wang at mentor.com
2017-04-13 12:14 ` jiada_wang
2017-04-13 12:14 ` [PATCH RFC 4/5] ARM: dts: imx: change compatiblity for SPI controllers on imx53 later soc jiada_wang
2017-04-13 12:14 ` jiada_wang at mentor.com
2017-04-13 12:14 ` jiada_wang
2017-04-13 12:14 ` [PATCH RFC 5/5] spi: imx: Add support for SPI Slave mode for imx53 and imx6 chips jiada_wang
2017-04-13 12:14 ` jiada_wang at mentor.com
2017-04-13 12:14 ` jiada_wang
2017-04-13 12:59 ` [PATCH RFC 0/5] *** SPI Slave mode support *** Mark Brown
2017-04-13 12:59 ` Mark Brown
2017-04-13 12:59 ` Mark Brown
2017-04-13 19:47 ` Geert Uytterhoeven
2017-04-13 19:47 ` Geert Uytterhoeven
2017-04-13 19:47 ` Geert Uytterhoeven
2017-04-14 5:39 ` Jiada Wang
2017-04-14 5:39 ` Jiada Wang
2017-04-14 5:39 ` Jiada Wang
2017-04-24 10:55 ` Geert Uytterhoeven
2017-04-24 10:55 ` Geert Uytterhoeven
2017-04-24 10:55 ` Geert Uytterhoeven
2017-04-24 12:48 ` Jiada Wang
2017-04-24 12:48 ` Jiada Wang
2017-04-24 12:48 ` Jiada Wang
2017-04-24 13:10 ` Geert Uytterhoeven
2017-04-24 13:10 ` Geert Uytterhoeven
2017-04-24 13:10 ` Geert Uytterhoeven
2017-04-25 7:56 ` Jiada Wang
2017-04-25 7:56 ` Jiada Wang
2017-04-25 7:56 ` Jiada Wang
2017-04-25 8:07 ` Uwe Kleine-König [this message]
2017-04-25 8:07 ` Uwe Kleine-König
2017-04-25 8:07 ` Uwe Kleine-König
2017-04-25 8:09 ` Geert Uytterhoeven
2017-04-25 8:09 ` Geert Uytterhoeven
2017-04-25 8:09 ` Geert Uytterhoeven
2017-04-25 10:31 ` Mark Brown
2017-04-25 10:31 ` Mark Brown
2017-04-25 10:31 ` Mark Brown
2017-04-27 6:43 ` Jiada Wang
2017-04-27 6:43 ` Jiada Wang
2017-04-27 6:43 ` Jiada Wang
2017-05-24 17:29 ` Mark Brown
2017-05-24 17:29 ` Mark Brown
2017-05-24 17:29 ` Mark Brown
2017-05-29 12:01 ` Fabio Estevam
2017-05-29 12:01 ` Fabio Estevam
2017-05-29 12:01 ` Fabio Estevam
2017-05-30 2:53 ` Jiada Wang
2017-05-30 2:53 ` Jiada Wang
2017-05-30 2:53 ` Jiada Wang
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