Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16with generic iowrite(read)8/16(be)

[Alexey Brodkin]

On 02/07/2013 06:51 PM, Grant Likely wrote:
> On Thu, Feb 7, 2013 at 2:39 PM, Grant Likely <grant.likely@xxxxxxxxxxxx> wrote:
> > On Wed, Feb 6, 2013 at 9:35 PM, Benjamin Herrenschmidt
> > <benh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > >   In fact, the driver already knows about this and figures
> > > > out at runtime how the device is wired up to the bus. This is not the
> > > > problem.
> > >
> > > Except that this is very gross, especially when you observe that in the
> > > busted "big endian" case, it has to byteswap the bloody data port.
> > >
> > > So you end up having to do that gross hack with separate accessors for
> > > registers vs. data and not able to use the _rep variants, which also
> > > means that on platforms like ppc, you end up with a memory barrier on
> > > every access (or more), which is going to slow things down enormously.
> >
> > I don't see why the _rep variants aren't usable here. The only reason
> > I didn't use them when I wrote the driver in the first place was I was
> > a n00b kernel hacker and I didn't know they were there.
>
> The 8-bit variant is different though because the hardware requires
> pingponging between odd and even byte addresses to flush the fifo.
> Reading a data port even address (0x40) gives the least significant
> byte. Reading from an odd address (0x41) give the MSB and pops the
> data off the FIFO. So, yes, the _rep variant can't be used in 8-bit
> mode. It should still be fine in 16-bit.
>
> page 45: http://www.xilinx.com/support/documentation/data_sheets/ds080.pdf

Ok, so may I do a re-spin with these changes:
1. In "ace_in_be16" use "ioread16be"
2. In "ace_out_be16" use "iowrite16be"
3. In "ace_in_le16" use "ioread16"
4. In "ace_out_le16" use "iowrite16"
5. In "ace_datain_le16" use "ioread16_rep"
6. In "ace_dataout_le16" use "iowrite16_rep"

not sure about items for "ace_datain/out_be16" - what about _rep options 
here?

-Alexey
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