Dear José Miguel Gonçalves,
> Hi Scott,
>
> On 09/13/2012 12:20 AM, Scott Wood wrote:
> > On 09/12/2012 06:16 PM, José Miguel Gonçalves wrote:
> >> Hi Marek,
> >>
> >> On 09/12/2012 10:11 PM, Marek Vasut wrote:
> >>> Dear José Miguel Gonçalves,
> >>>
> >>>> +
> >>>> +/*
> >>>> + * Hardware specific access to control-lines function
> >>>> + */
> >>>> +static void s3c_nand_hwcontrol(struct mtd_info *mtd, int cmd,
> >>>> unsigned int
> >>>> ctrl) +{
> >>>> + s3c24xx_nand *const nand = s3c24xx_get_base_nand();
> >>>> + struct nand_chip *this = mtd->priv;
> >>>> +
> >>>> + if (ctrl & NAND_CTRL_CHANGE) {
> >>>> + if (ctrl & NAND_CLE)
> >>>> + this->IO_ADDR_W = (void __iomem *)&nand->nfcmmd;
> >>>> + else if (ctrl & NAND_ALE)
> >>>> + this->IO_ADDR_W = (void __iomem *)&nand->nfaddr;
> >>>> + else
> >>>> + this->IO_ADDR_W = (void __iomem *)&nand->nfdata;
> >>>
> >>> Do you need this cast ?
> >>
> >> Without it gcc gives me a warning:
> >>
> >> s3c24xx_nand.c:90:20: warning: assignment discards `volatile' qualifier
> >> from pointer target type [enabled by default]
> >
> > Why do you have volatile in your s3c24xx_nand struct?
>
> I use that as a rule to memory mapping of hardware registers.
> Without it GCC optimization sometimes do bad things, like completely
> removing sequences of code.
Not true unless your gcc is broken. Use proper accessors (readl()/writel()),
they have proper barriers already.
> For instance, if you need to pause in a loop until some bit of a
> register is changed (as it's done in the serial driver) and the struct
> were this register is mapped don't have the volatile attribute, the GCC
> optimizer removes the loop.
Yes, see above.
> Regards,
> José Gonçalves
Best regards,
Marek Vasut
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
