Hi Arnd,
> Subject: Re: [PATCHv8 1/4] pwm: Add Freescale FTM PWM driver support
>
> On Thursday 02 January 2014 17:57:01 Xiubo Li wrote:
> > +static inline u32 ftm_readl(bool big_endian, const void __iomem *addr)
> > +{
> > + u32 val;
> > +
> > + val = __raw_readl(addr);
> > +
> > + if (likely(big_endian))
> > + val = be32_to_cpu((__force __be32)val);
> > + else
> > + val = le32_to_cpu((__force __le32)val);
> > + rmb();
> > +
> > + return val;
> > +}
> > +
> > +static inline void ftm_writel(bool big_endian, u32 val, void __iomem *addr)
> > +{
> > + wmb();
> > + if (likely(big_endian))
> > + val = (__force u32)cpu_to_be32(val);
> > + else
> > + val = (__force u32)cpu_to_le32(val);
> > +
> > + __raw_writel(val, addr);
>
> These functions definitely need some comments regarding why this is necessary.
> I assume that after 8 rounds of review (that I did not read) this has been
> discussed already, so please explain above the functions why you don't just
> use ioread32be/ioread32 and iowrite32be/iowrite32 here.
>
As Thierry has commonts in some days before:
----
A few years ago GregKH commented in response to a patch that ioread*()
weren't supposed to be used for memory-mapped only devices. The original
purpose apparently was to allow drivers to work with both I/O and
memory-mapped devices.
----
I'm not very sure.
The big-endian supports is added at v7~v8 patch series.
> Also all callers seem to be of the style
>
> val = ftm_readl(fpc->big_endian, fpc->base + FTM_SC);
>
> so I wonder why you don't just pass the fpc pointer to the function
> and make it
>
> static inline void ftm_readl(struct fsl_pwm_chip *fpc, unsigned long reg, u32
> val)
> {
> if (fpc->big_endian)
> iowrite32be(val, fpc->base + reg);
> else
> iowrite32(val, fpc->base + reg);
> }
>
Yes, it was.
I thought this will make the ftm_readl/ftm_writel look more brief like other drivers.
Thanks very much.
--
Best Regards,
Xiubo
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