linux-kernel - [PATCH] rtc: rtc-twl: fix initialization sequence

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Date:	Wed, 5 Jun 2013 14:19:22 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	<rtc-linux@...glegroups.com>,
	Andrew Morton <akpm@...ux-foundation.org>
CC:	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Tony Lindgren <tony@...mide.com>
Subject: [PATCH] rtc: rtc-twl: fix initialization sequence

The twl-rtc has the following dependencies from other drivers during the boot:
pinctrl
|-i2c-omap
  |- twl-core
     |- twl-rtc

The i2c-omap probe may be deferred because pinctrl iss not ready yet. As result,
i2c-omap will be probed at late init time. Which, in turn, will delay twl-core
initialization till late init time too.

But, the twl-rtc driver is registered from finction twl_rtc_init() at
module(device) init time and contains part of its initialization code within it.
Unfortunatelly, this code depends on twl-core which may be not ready at that
moment and, as result, wrong register map will be selected
(on OMAP3 twl6030_rtc_reg_map will be selected instead of twl4030_rtc_reg_map).

static int __init twl_rtc_init(void)
{
    if (twl_class_is_4030()) <--- twl-core might be not ready here
                             <--- and twl_class_is_4030() will return 0
        rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
    else
        rtc_reg_map = (u8 *) twl6030_rtc_reg_map;

    return platform_driver_register(&twl4030rtc_driver);
}

Hence, move register map selection code in twl_rtc_probe() to solve this issue.

Cc: Alessandro Zummo <a.zummo@...ertech.it>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Tony Lindgren <tony@...mide.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/rtc/rtc-twl.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c
index bbda0fd..1698115 100644
--- a/drivers/rtc/rtc-twl.c
+++ b/drivers/rtc/rtc-twl.c
@@ -481,6 +481,11 @@ static int twl_rtc_probe(struct platform_device *pdev)
 	if (irq <= 0)
 		goto out1;
 
+	if (twl_class_is_4030())
+		rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
+	else
+		rtc_reg_map = (u8 *) twl6030_rtc_reg_map;
+
 	ret = twl_rtc_read_u8(&rd_reg, REG_RTC_STATUS_REG);
 	if (ret < 0)
 		goto out1;
@@ -622,11 +627,6 @@ static struct platform_driver twl4030rtc_driver = {
 
 static int __init twl_rtc_init(void)
 {
-	if (twl_class_is_4030())
-		rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
-	else
-		rtc_reg_map = (u8 *) twl6030_rtc_reg_map;
-
 	return platform_driver_register(&twl4030rtc_driver);
 }
 module_init(twl_rtc_init);
-- 
1.7.9.5

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