mail archive of the barebox mailing list
 help / color / mirror / Atom feed
From: Bastian Stender <bst@pengutronix.de>
To: barebox@lists.infradead.org
Cc: Bastian Stender <bst@pengutronix.de>
Subject: [PATCH 1/2] i2c: mv64xxx: add software delays
Date: Thu, 23 Feb 2017 17:34:49 +0100	[thread overview]
Message-ID: <20170223163450.6611-1-bst@pengutronix.de> (raw)

As stated in Marvell's Functional Specifications in MV-S107021-U0 Rev. A
on page 420 ff. software delays are needed. "SW delay represent a delay
of at least 2 internal clock cycles". These delays are hereby
implemented.

The original kernel driver compensates the needed software delays with
the time the interrupts take.

Signed-off-by: Bastian Stender <bst@pengutronix.de>
---
 drivers/i2c/busses/i2c-mv64xxx.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 9b9e6c953f..45d5a2b6dc 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -270,6 +270,7 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status)
 		}
 		/* FALLTHRU */
 	case STATUS_MAST_RD_DATA_ACK: /* 0x50 */
+		udelay(2);
 		if (status != STATUS_MAST_RD_DATA_ACK)
 			drv_data->action = ACTION_CONTINUE;
 		else {
@@ -280,6 +281,7 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status)
 
 		if (drv_data->bytes_left == 1)
 			drv_data->cntl_bits &= ~REG_CONTROL_ACK;
+			udelay(2);
 		break;
 
 	case STATUS_MAST_RD_DATA_NO_ACK: /* 0x58 */
@@ -318,6 +320,8 @@ static void mv64xxx_i2c_send_start(struct mv64xxx_i2c_data *drv_data)
 	mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
 	mv64xxx_write(drv_data, drv_data->cntl_bits | REG_CONTROL_START,
 		drv_data->reg_offsets.control);
+
+	udelay(2);
 }
 
 static void
@@ -333,7 +337,7 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 		mv64xxx_i2c_send_start(drv_data);
 
 		if (drv_data->errata_delay)
-			udelay(5);
+			udelay(3);
 
 		/*
 		 * We're never at the start of the message here, and by this
@@ -349,6 +353,7 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 		break;
 
 	case ACTION_SEND_ADDR_1:
+		udelay(2);
 		mv64xxx_write(drv_data, drv_data->addr1,
 			drv_data->reg_offsets.data);
 		mv64xxx_write(drv_data, drv_data->cntl_bits,
@@ -360,9 +365,11 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 			drv_data->reg_offsets.data);
 		mv64xxx_write(drv_data, drv_data->cntl_bits,
 			drv_data->reg_offsets.control);
+		udelay(2);
 		break;
 
 	case ACTION_SEND_DATA:
+		udelay(2);
 		mv64xxx_write(drv_data, drv_data->msg->buf[drv_data->byte_posn++],
 			drv_data->reg_offsets.data);
 		mv64xxx_write(drv_data, drv_data->cntl_bits,
@@ -383,8 +390,9 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 		mv64xxx_write(drv_data, drv_data->cntl_bits | REG_CONTROL_STOP,
 			drv_data->reg_offsets.control);
 		drv_data->block = false;
+		udelay(2);
 		if (drv_data->errata_delay)
-			udelay(5);
+			udelay(3);
 
 		break;
 
-- 
2.11.0


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

             reply	other threads:[~2017-02-23 16:35 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-23 16:34 Bastian Stender [this message]
2017-02-23 16:34 ` [PATCH 2/2] i2c: mv64xxx: simplify mv64xxx_i2c_wait_for_completion Bastian Stender
2017-02-24  7:24 ` [PATCH 1/2] i2c: mv64xxx: add software delays Sascha Hauer

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=20170223163450.6611-1-bst@pengutronix.de \
    --to=bst@pengutronix.de \
    --cc=barebox@lists.infradead.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