[U-Boot] [Patch V3] i2c: mxc: add a condition in case the parameter is NULL

[Qianyu Gong]

> -----Original Message-----
> From: Heiko Schocher [mailto:hs at denx.de]
> Sent: Friday, December 18, 2015 6:24 PM
> To: Gong Qianyu-B52263
> Cc: u-boot at lists.denx.de; Stefano Babic
> Subject: Re: [U-Boot] [Patch V3] i2c: mxc: add a condition in case the
> parameter is NULL
> 
> Hello Gong Qianyu,
> 
> added Stefano Babic to cc as he is the imx maintainer.
> 
> Am 18.12.2015 um 10:38 schrieb Gong Qianyu:
> > This could avoid executing the code that only applies to i.MX platforms.
> >
> > The bus_i2c_init() is called before relocation and will assgin value
> > to a static variable. If U-Boot is then still running in a flash
> > device, it's theoretically not allowed to write data to flash without
> > an erasing operation. For i.MX platforms, the U-Boot is always running
> > in DDR.
> >
> > Actually it causes asynchronous error when the ARM64 system error
> > report is enabled and the flash write protect is set.
> >
> > Signed-off-by: Gong Qianyu <Qianyu.Gong at freescale.com>
> > ---
> > V3:
> >   - Sorry..Remove an unrelated line in other file.
> >
> >   drivers/i2c/mxc_i2c.c | 12 ++++++++++--
> >   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> Ok, from my side, but it would be better to switch your board(s) to
> support DM and get rid of this old stuff from this driver.
> 
> Reviewed-by: Heiko Schocher <hs at denx.de>
> 
> bye,
> Heiko

Thanks. But I have no control over this driver. Maybe they are considering to 
convert it later.

Regards,
Qianyu

> >
> > diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index
> > fa4c82f..b2d15c9 100644
> > --- a/drivers/i2c/mxc_i2c.c
> > +++ b/drivers/i2c/mxc_i2c.c
> > @@ -581,8 +581,16 @@ void bus_i2c_init(int index, int speed, int unused,
> >   		return;
> >   	}
> >
> > -	mxc_i2c_buses[index].idle_bus_fn = idle_bus_fn;
> > -	mxc_i2c_buses[index].idle_bus_data = idle_bus_data;
> > +	/*
> > +	 * Warning: Be careful to allow the assignment to a static
> > +	 * variable here. This function could be called while U-Boot is
> > +	 * still running in flash memory. So such assignment is equal
> > +	 * to write data to flash without erasing.
> > +	 */
> > +	if (idle_bus_fn)
> > +		mxc_i2c_buses[index].idle_bus_fn = idle_bus_fn;
> > +	if (idle_bus_data)
> > +		mxc_i2c_buses[index].idle_bus_data = idle_bus_data;
> >
> >   	ret = enable_i2c_clk(1, index);
> >   	if (ret < 0) {
> >
> 
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