linux-kernel - [RFC 2/2] i2c: gpio: drop class based instantiation of slaves

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Date:	Wed, 19 Jun 2013 21:22:12 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-i2c@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Haavard Skinnemoen <hskinnemoen@...il.com>
Subject: [RFC 2/2] i2c: gpio: drop class based instantiation of slaves

Class based instantiation mechanism can cause huge delays when booting.
For example: when CONFIG_SENSORS_LM75 option is enabled for or omap5-uevm board,
where i2c-gpio is used for HDMI edid reading - it introduces up to 5 sec boot
delay.
It's not recommended to use this mechanism with embedded I2C, so disable it by
leaving I2C adapter "class" field undefined (remove I2C_CLASS_HWMON and
I2C_CLASS_SPD) and add a deprecation warning to allow users, relying on this
mechanism, to switch to something better.

CC: Haavard Skinnemoen <hskinnemoen@...il.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/i2c/busses/i2c-gpio.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c
index bc6e139..33e3d0e 100644
--- a/drivers/i2c/busses/i2c-gpio.c
+++ b/drivers/i2c/busses/i2c-gpio.c
@@ -215,7 +215,7 @@ static int i2c_gpio_probe(struct platform_device *pdev)
 		snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
 
 	adap->algo_data = bit_data;
-	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	adap->class = I2C_CLASS_DEPRECATED;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
 
-- 
1.7.9.5

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