All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ian Dannapel <iansdannapel@gmail.com>
To: linux@rempel-privat.de
Cc: kernel@pengutronix.de, shawnguo@kernel.org,
	s.hauer@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
	linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Michael.Glembotzki@iris-sensing.com,
	Erik.Schumacher@iris-sensing.com,
	Ian Dannapel <iansdannapel@gmail.com>
Subject: [PATCH] i2c: imx: remove unnecessary delay at startup
Date: Mon, 14 Mar 2022 10:59:18 +0100	[thread overview]
Message-ID: <20220314095918.50014-1-iansdannapel@gmail.com> (raw)

a delay on the startup of the i2c imx controller is not required or defined in the specs.
By removing it, the user can see a latency decrease from up to 150μs in communication.
Additional info: https://lore.kernel.org/all/20220304132037.GA15901@pengutronix.de/

Signed-off-by: Ian S. Dannapel <iansdannapel@gmail.com>
---
 drivers/i2c/busses/i2c-imx.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 3576b63a6c03..019dda5301df 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -602,12 +602,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool atomic)
 	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
 	imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode, i2c_imx, IMX_I2C_I2CR);
 
-	/* Wait controller to be stable */
-	if (atomic)
-		udelay(50);
-	else
-		usleep_range(50, 150);
-
 	/* Start I2C transaction */
 	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
 	temp |= I2CR_MSTA;
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Ian Dannapel <iansdannapel@gmail.com>
To: linux@rempel-privat.de
Cc: kernel@pengutronix.de, shawnguo@kernel.org,
	s.hauer@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
	linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Michael.Glembotzki@iris-sensing.com,
	Erik.Schumacher@iris-sensing.com,
	Ian Dannapel <iansdannapel@gmail.com>
Subject: [PATCH] i2c: imx: remove unnecessary delay at startup
Date: Mon, 14 Mar 2022 10:59:18 +0100	[thread overview]
Message-ID: <20220314095918.50014-1-iansdannapel@gmail.com> (raw)

a delay on the startup of the i2c imx controller is not required or defined in the specs.
By removing it, the user can see a latency decrease from up to 150μs in communication.
Additional info: https://lore.kernel.org/all/20220304132037.GA15901@pengutronix.de/

Signed-off-by: Ian S. Dannapel <iansdannapel@gmail.com>
---
 drivers/i2c/busses/i2c-imx.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 3576b63a6c03..019dda5301df 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -602,12 +602,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool atomic)
 	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
 	imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode, i2c_imx, IMX_I2C_I2CR);
 
-	/* Wait controller to be stable */
-	if (atomic)
-		udelay(50);
-	else
-		usleep_range(50, 150);
-
 	/* Start I2C transaction */
 	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
 	temp |= I2CR_MSTA;
-- 
2.25.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2022-03-14  9:59 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-14  9:59 Ian Dannapel [this message]
2022-03-14  9:59 ` [PATCH] i2c: imx: remove unnecessary delay at startup Ian Dannapel
2022-03-14 10:13 ` Uwe Kleine-König
2022-03-14 10:13   ` Uwe Kleine-König
2022-03-15  5:59   ` Oleksij Rempel
2022-03-15  5:59     ` Oleksij Rempel
2022-03-15  7:44     ` Wolfram Sang
2022-03-15  7:44       ` Wolfram Sang

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=20220314095918.50014-1-iansdannapel@gmail.com \
    --to=iansdannapel@gmail.com \
    --cc=Erik.Schumacher@iris-sensing.com \
    --cc=Michael.Glembotzki@iris-sensing.com \
    --cc=festevam@gmail.com \
    --cc=kernel@pengutronix.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rempel-privat.de \
    --cc=s.hauer@pengutronix.de \
    --cc=shawnguo@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 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.