[PATCH v5 1/3] ARM: mxs: add GPMI-NFC support for imx23/imx28

[Lothar Waßmann]

Hi,

Arnd Bergmann writes:
> On Thursday 30 June 2011, Huang Shijie wrote:
> > add GPMI-NFC support for imx23 and imx28.
> > 
> > Signed-off-by: Huang Shijie <b32955 at freescale.com>
> 
[...]
> > +struct gpmi_nfc_platform_data {
> > +	/* SoC hardware information. */
> > +	int		(*platform_init)(void);
> > +	void		(*platform_exit)(void);
> > +
> > +	/* NAND Flash information. */
> > +	unsigned int	min_prop_delay_in_ns;
> > +	unsigned int	max_prop_delay_in_ns;
> > +	unsigned int	max_chip_count;
> > +
> > +	/* Medium information. */
> > +	struct mtd_partition *partitions;
> > +	unsigned	partition_count;
> > +};
> 
> When adding new infrastructure, always keep in mind how you want it to look
> after the device tree conversion. The partitions and min/max_* are easily covered
> with that, but the init/exit function pointers are somewhat problematic.
> 
> Fortunately, you don't really require these functions for this driver. The _exit
> function is completely unused, so just get rid of it.
> 
> The init function is used only to set up iomux, so the logical replacement is
> a pointer to the iomux data, and calling mxs_iomux_setup_multiple_pads
> directly from the driver.
> 
NO! I strongly object that. mxs_iomux_setup_multiple_pads() is a
platform specific function and has no business inside a device driver
that should be platform agnostic.
Consider the same controller being part of a different SoC that
requires you to call mxs_iomux_v2_setup_multiple_pads() instead. You
would then have to check for the SoC type inside the driver to find
the right function to call which is quite obscene.

I would rather live with the iomux statically configured in the
platform init code than having direct calls into platform specific
code from device drivers.


Lothar Waßmann
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