Re: [PATCH 1/2] i2c: omap: convert to module_platform_driver()

[Grygorii Strashko]

Hi Kevin,
On 06/03/2013 11:59 PM, Kevin Hilman wrote:
> Grygorii Strashko <grygorii.strashko@xxxxxx> writes:
>
> > The OMAP I2C driver has a relation to pinctrl-single driver. As result,
> > its probe will be deferred during system boot until late init time,
> > because the pinctrl-single is initizalized as moudle/device init time.
> > This, in turn, will delay initialization of all I2C devices (like mfd,
> > I2C regulators and etc.) and cause boot delay (more over, it can broken
> > initialization of drivers which are not ready to use deferred probe
> > mechanism yet, for example DSS).
> >
> > There are no sense to keep OMAP I2C initialization on subsys init layer
> > any more, hence shift it to module/device layer where the i2c <-->
> > pinctrl-single dependency is resolved in drivers/Makefile now.
> >
> > Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> > Cc: "Ben Dooks (embedded platforms)" <ben-linux@xxxxxxxxx>
> > Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> > Cc: linux-omap@xxxxxxxxxxxxxxx
> > Cc: linux-i2c@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> >
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> Testing this patch with PATCH 1/2, the twl_rtc driver fails to correctly
> initialize on OMAP3:
>
>           twl_rtc rtc.22: hctosys: invalid date/time
>
> instead of the expected result:
>
>            twl_rtc rtc.22: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
>
> so something is still not right for the init sequence.
>
> Kevin
I think, the root cause of the problem isn't this patch - it's just yet 
another side effect
of using deferred probes :). I've taken a look on twl-rtc code and found 
possible error place
static int __init twl_rtc_init(void)
{
    if (twl_class_is_4030()) <------ here,
        rtc_reg_map = (u8 *) twl4030_rtc_reg_map;
    else
        rtc_reg_map = (u8 *) twl6030_rtc_reg_map;

    return platform_driver_register(&twl4030rtc_driver);
}
In drivers/Makefile:
obj-$(CONFIG_RTC_LIB)        += rtc/  <------ RTC is placed before I2C
obj-y                += i2c/ media/ <----- and only here I2C bus 
instantiates TWL-core device
and configures twl_priv->twl_id

Thats why it's working on my OMAP4/twl6030 board. Could you check if 
below fix will work on OMAP3:
diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c
index 8751a52..aaa5015 100644
--- a/drivers/rtc/rtc-twl.c
+++ b/drivers/rtc/rtc-twl.c
@@ -469,6 +469,11 @@ 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;
@@ -610,11 +615,6 @@ 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);

Unfortunately, I have no OMAP3 HW and can't check it.

Regards,
-grygorii


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