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

[Grygorii Strashko]

On 06/04/2013 09:29 PM, Kevin Hilman wrote:
> Grygorii Strashko <grygorii.strashko@xxxxxx> writes:
>
> > 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:
> Yes, your fix works.  Thanks for digging into it.
>
> Care to send a proper patch?  Please be sure to send to Andrew Morton
> also, since he'll be the one to queue the RTC patch.
Hi Kevin,

The similar patch already exists:
https://patchwork.kernel.org/patch/2448251/ - [v2,1/2] RTC: rtc-twl: Fix 
rtc_reg_map initialization
from Peter Ujfalusi

-grygorii

> > 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.
> I suggest you find a Beagle or Gumstix/Overo type board someplace.
> There is an abundance of cheap OMAP3 hardware available.
>
> Kevin

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/