linux-kernel - [PATCH v2] w1: add fast search for single slave bus

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Date:	Sun,  4 Dec 2011 17:46:50 +0100
From:	Hubert Feurstein <h.feurstein@...il.com>
To:	zbr@...emap.net, jeff.dagenais@...il.com
Cc:	linux-kernel@...r.kernel.org,
	Hubert Feurstein <h.feurstein@...il.com>
Subject: [PATCH v2] w1: add fast search for single slave bus

This enables a much more efficient way of device searching. It uses the
1-wire read-rom operation which allows the direct reading of the slave
address. BUT this works only with exactly one slave on the bus.

Signed-off-by: Hubert Feurstein <h.feurstein@...il.com>
---
 v2: remove config option

 drivers/w1/w1.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index c374978..9761950 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -892,6 +892,16 @@ void w1_search(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb
 			break;
 		}
 
+		/* Do fast search on single slave bus */
+		if (dev->max_slave_count == 1) {
+			w1_write_8(dev, W1_READ_ROM);
+
+			if (w1_read_block(dev, (u8 *)&rn, 8) == 8 && rn)
+				cb(dev, rn);
+
+			break;
+		}
+
 		/* Start the search */
 		w1_write_8(dev, search_type);
 		for (i = 0; i < 64; ++i) {
-- 
1.7.7.4

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