From: Alexandru Ardelean <alexandru.ardelean@analog.com>
To: <linux-iio@vger.kernel.org>, <linux-spi@vger.kernel.org>,
<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <jic23@kernel.org>, <robh+dt@kernel.org>, <mark.rutland@arm.com>,
<broonie@kernel.org>,
Alexandru Ardelean <alexandru.ardelean@analog.com>,
Michael Hennerich <michael.hennerich@analog.com>
Subject: [PATCH 1/4][V2] drivers: spi: core: Add optional delay between cs_change transfers
Date: Wed, 17 Jul 2019 14:51:06 +0300 [thread overview]
Message-ID: <20190717115109.15168-2-alexandru.ardelean@analog.com> (raw)
In-Reply-To: <20190717115109.15168-1-alexandru.ardelean@analog.com>
Some devices like the ADIS16460 IMU require a stall period between
transfers, i.e. between when the CS is de-asserted and re-asserted. The
default value of 10us is not enough. This change makes the delay
configurable for when the next CS change goes active.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/spi/spi.c | 3 ++-
include/linux/spi/spi.h | 3 +++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 5e75944ad5d1..02fd00bcaace 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1163,7 +1163,8 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
keep_cs = true;
} else {
spi_set_cs(msg->spi, false);
- udelay(10);
+ udelay(xfer->cs_change_delay_usecs ?
+ xfer->cs_change_delay_usecs : 10);
spi_set_cs(msg->spi, true);
}
}
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 053abd22ad31..c884b3b94841 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -734,6 +734,8 @@ extern void spi_res_release(struct spi_controller *ctlr,
* transfer. If 0 the default (from @spi_device) is used.
* @bits_per_word: select a bits_per_word other than the device default
* for this transfer. If 0 the default (from @spi_device) is used.
+ * @cs_change_delay_usecs: microseconds to delay between cs_change
+ * transfers.
* @cs_change: affects chipselect after this transfer completes
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
@@ -823,6 +825,7 @@ struct spi_transfer {
#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */
u8 bits_per_word;
u8 word_delay_usecs;
+ u8 cs_change_delay_usecs;
u16 delay_usecs;
u32 speed_hz;
u16 word_delay;
--
2.20.1
next prev parent reply other threads:[~2019-07-17 11:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 11:51 [PATCH 0/4][V2] iio: imu: Add support for the ADIS16460 IMU Alexandru Ardelean
2019-07-17 11:51 ` Alexandru Ardelean [this message]
2019-07-18 12:50 ` [PATCH 1/4][V2] drivers: spi: core: Add optional delay between cs_change transfers Mark Brown
2019-07-18 13:36 ` Ardelean, Alexandru
2019-07-17 11:51 ` [PATCH 2/4][V2] iio: imu: adis: Add support for SPI transfer cs_change_delay_usecs Alexandru Ardelean
2019-07-17 11:51 ` [PATCH 3/4][V2] iio: imu: Add support for the ADIS16460 IMU Alexandru Ardelean
2019-07-17 11:51 ` [PATCH 4/4][V2] dt-bindings: iio: imu: add bindings for ADIS16460 Alexandru Ardelean
2019-07-19 22:49 ` Rob Herring
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=20190717115109.15168-2-alexandru.ardelean@analog.com \
--to=alexandru.ardelean@analog.com \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=jic23@kernel.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=michael.hennerich@analog.com \
--cc=robh+dt@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).