Re: [PATCH 1/5] i2c: mv64xxx: Add reset deassert call

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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Hi,

On Fri, Jan 10, 2014 at 01:48:41PM +0800, Chen-Yu Tsai wrote:
> On Fri, Jan 10, 2014 at 1:19 AM, Maxime Ripard
> <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote:
> > The Allwinner A31 SoC using that IP has a reset controller maintaining
> > it reset unless told otherwise.
> >
> > Add some optional reset support to the driver.
> >
> > Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> > ---
> >  Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt | 1 +
> >  drivers/i2c/busses/Kconfig                            | 1 +
> >  drivers/i2c/busses/i2c-mv64xxx.c                      | 6 ++++++
> >  3 files changed, 8 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt b/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
> > index 82e8f6f..603003a 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mv64xxx.txt
> > @@ -12,6 +12,7 @@ Optional properties :
> >
> >   - clock-frequency : Desired I2C bus clock frequency in Hz. If not set the
> >  default frequency is 100kHz
> > + - resets          : phandle to the parent reset controller
> >
> >  Examples:
> >
> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> > index 3b26129..69aa599 100644
> > --- a/drivers/i2c/busses/Kconfig
> > +++ b/drivers/i2c/busses/Kconfig
> > @@ -528,6 +528,7 @@ config I2C_MPC
> >  config I2C_MV64XXX
> >         tristate "Marvell mv64xxx I2C Controller"
> >         depends on (MV64X60 || PLAT_ORION || ARCH_SUNXI)
> > +       select RESET_CONTROLLER
> >         help
> >           If you say yes to this option, support will be included for the
> >           built-in I2C interface on the Marvell 64xxx line of host bridges.
> > diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> > index 8be7e42..d4e2f32 100644
> > --- a/drivers/i2c/busses/i2c-mv64xxx.c
> > +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/interrupt.h>
> >  #include <linux/mv643xx_i2c.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/reset.h>
> >  #include <linux/io.h>
> >  #include <linux/of.h>
> >  #include <linux/of_device.h>
> > @@ -743,6 +744,7 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
> >  #else
> >         const struct of_device_id *device;
> >         struct device_node *np = dev->of_node;
> > +       struct reset_control *rstc;
> >         u32 bus_freq, tclk;
> >         int rc = 0;
> >
> > @@ -763,6 +765,10 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
> >         }
> >         drv_data->irq = irq_of_parse_and_map(np, 0);
> >
> > +       rstc = devm_reset_control_get(dev, NULL);
> > +       if (!IS_ERR(rstc))
> > +               reset_control_deassert(rstc);
> > +
> 
> Do we need to handle -EPROBE_DEFER here?

Hmmm, true.

> Also no reset_control_assert() in the exit path?
> I'm asking because I have similar code in my stmmac patches.

That might be a good idea indeed.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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