On Tue, 9 Sep 2008 17:44:59 +0100, Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
> > command/status registers, but the register layout is swapped on big
> > endian. There are some other endian issue and some special registers
> > which requires many custom dma_ops/port_ops routines.
>
> It would probably be a lot cleaner using the libata framework, and also
> go obsolete less soon.
Yes, that's future plan.
> > +#define TX4939IDE_writeb(val, base, reg) \
> > + __raw_writeb(val, (void __iomem *)((base) + TX4939IDE_REG8(reg)))
>
> It's generally frowned upon to hide all the detail in macros, it is much
> easier to read and understand the code if you don't do this.
OK, I'll try to make much readble.
> > +#define TX4939IDE_BASE(hwif) ((hwif)->io_ports.data_addr & ~0xfff)
>
> Why do you have void __iomem casts all over the write methods not in the
> _BASE() method - that would let sparse do its job properly
Indeed. I'll do it.
> > + for (i = 0; i < MAX_DRIVES; i++) {
> > + if (drive != &hwif->drives[i] &&
>
> You don't actually need the first test. This also appears wrong. In your
> tests MW_DMA_0 is 'faster' than PIO4 but in fact MW_DMA_0 PIO timings are
> *slower* than PIO4 so the mode is not in fact slower.
>
> > + case XFER_MW_DMA_2:
> > + case XFER_MW_DMA_1:
> > + case XFER_MW_DMA_0:
> > + case XFER_PIO_4:
> > + value |= 0x0400;
> > + break;
>
> This looks odd according to the speed tables. Can you clarify what is
> going on ?
As you and Sergei pointed out, the code seems somewhat broken. I'll
rework on it.
> > +#ifdef __BIG_ENDIAN
> > + {
> > + unsigned int *table = hwif->dmatable_cpu;
> > + while (1) {
> > + cpu_to_le64s((u64 *)table);
> > + if (*table & 0x80000000)
> > + break;
>
> You modify the table but you never ensure the data is not still in
> temporary variables from the compiler or flushed from cache
The dmatable_cpu is allocated by pci_alloc_consistent so that flush is
not needed. But... this is not PCI device. I should not use
ide_allocate_dma_engine(). I'll fix it.
Thank you for review.
---
Atsushi Nemoto
