[U-Boot] [PATCH] serial: ns16550: fix different reg size access

[Wolfgang Denk <wd@denx.de>]

Dear Lei Wen,

In message <AANLkTinqAyDx7=61FMgPdCg3ULt9nk93jF-y0Sdi=5uX@mail.gmail.com> you wrote:
>
> >> I think my code also could handle this. They only could set the
> >> CONFIG_SYS_NS16550_REG_SIZE =A0to be 1
> >> and CONFIG_SYS_NS16550_MAX_REG_SIZE to be 4. Then
> >> the other bits is untouched by this driver.
> >
> > I don't think so. You still use just a single writel() call then. =A0To
> > leave the other bits untouched, you would have to perform a readl()
> > first, then insert one data byte, and then write it back. =A0Your patch
> > does not do that.
> 
> My original patch is like below, so where it call writel?...
> +#elif (CONFIG_SYS_NS16550_REG_SIZE == 1) || (CONFIG_SYS_NS16550_REG_SIZE == -1)
> +#ifdef CONFIG_SYS_NS16550_PORT_MAPPED
> +#define serial_out(x, y)       outb(x, y)
> +#define serial_in(y)           inb(y)
> +#else
> +#define serial_out(x, y)       writeb(x, y)
> +#define serial_in(y)           readb(y)

If you use writeb() [as the current driver would do as well}, then how
do you expect to set this bit 8 (which is in the next byte) to 0 as
you claim you have to?

Either I don't understand what you want, or you don't understand how
the ns16550 driver works.

I can see no shortcomings in the existent driver, thus no need to
make it more complicated than it already is.


Best regards,

Wolfgang Denk

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