linux-kernel - [PATCH] sm501: When registering the GPIO, turn on the GPIO unit's power

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Message-ID: <20110706034138.GA8987@leaf>
Date:	Tue, 5 Jul 2011 20:41:40 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	Samuel Ortiz <sameo@...ux.intel.com>,
	Paul Mundt <lethal@...ux-sh.org>, Ben Dooks <ben@...tec.co.uk>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	psas-avionics@...ts.psas.pdx.edu
Subject: [PATCH] sm501: When registering the GPIO, turn on the GPIO unit's
 power

When attempting to use GPIO via the sm501 unit on the TQM5200 board,
GPIO operations would only function if during the same boot u-boot's
"fkt led" command had initialized the sm501.  Comparing the sm501's
registers with and without running the "fkt led" command turned up one
significant difference: u-boot had enabled the GPIO power gate.
Changing the Linux sm501 driver to enable the GPIO power gate allows
GPIO to work without first initializing it with u-boot.

Signed-off-by: Josh Triplett <josh@...htriplett.org>
---
 drivers/mfd/sm501.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/mfd/sm501.c b/drivers/mfd/sm501.c
index df3702c..d7a0ab9 100644
--- a/drivers/mfd/sm501.c
+++ b/drivers/mfd/sm501.c
@@ -1089,6 +1089,7 @@ static int __devinit sm501_register_gpio(struct sm501_devdata *sm)
 		goto err_low_chip;
 	}
 
+	sm501_unit_power(sm->dev, SM501_GATE_GPIO, 1);
 	gpio->registered = 1;
 
 	return 0;
@@ -1118,6 +1119,8 @@ static void sm501_gpio_remove(struct sm501_devdata *sm)
 	if (!sm->gpio.registered)
 		return;
 
+	sm501_unit_power(sm->dev, SM501_GATE_GPIO, 0);
+
 	ret = gpiochip_remove(&gpio->low.gpio);
 	if (ret)
 		dev_err(sm->dev, "cannot remove low chip, cannot tidy up\n");
-- 
1.7.5.4

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