mail archive of the barebox mailing list
 help / color / mirror / Atom feed
From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: barebox@lists.infradead.org
Subject: [PATCH 2/2] i2c_probe: Use a quick write transfer instead of writing a zero
Date: Fri, 25 Jan 2019 21:59:35 +0100	[thread overview]
Message-ID: <20190125205935.15135-2-u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <20190125205935.15135-1-u.kleine-koenig@pengutronix.de>

This matches the method implemented in i2cdetect(8) when using its -q
option.

With this change an rx8130 RTC is detectable using i2c_probe. This
failed before because this chip acks the first byte (containing its
address and the R/̅W bit) but nacks the following 0 (representing the
target address to write nothing to) which makes i2c_write_reg() return
with an error and so the chip is not listed as available.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 commands/i2c.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/commands/i2c.c b/commands/i2c.c
index 65ff7378ec14..77d65e3fa32b 100644
--- a/commands/i2c.c
+++ b/commands/i2c.c
@@ -24,19 +24,19 @@
 
 static void i2c_probe_range(struct i2c_adapter *adapter, int startaddr, int stopaddr)
 {
-	struct i2c_client client = {};
 	int addr;
-	int ret;
-	u8 reg;
-
-	client.adapter = adapter;
 
 	printf("probing i2c%d range 0x%02x-0x%02x: ", adapter->nr, startaddr, stopaddr);
 	for (addr = startaddr; addr <= stopaddr && !ctrlc(); addr++) {
-		client.addr = addr;
-		ret = i2c_write_reg(&client, 0x00, &reg, 0);
-		if (ret == 0)
+		struct i2c_msg msg = {
+			.addr = addr,
+			.buf = NULL,
+			.len = 0,
+		};
+		int ret = i2c_transfer(adapter, &msg, 1);
+		if (ret == 1)
 			printf("0x%02x ", addr);
+
 	}
 	printf("\n");
 }
-- 
2.20.1


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

  reply	other threads:[~2019-01-25 20:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-25 20:59 [PATCH 1/2] i2c_probe: limit slave addresses to [0x04, 0x77] Uwe Kleine-König
2019-01-25 20:59 ` Uwe Kleine-König [this message]
2019-01-28  9:01 ` 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=20190125205935.15135-2-u.kleine-koenig@pengutronix.de \
    --to=u.kleine-koenig@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