Messages in this thread | | | Date | Thu, 7 Feb 2013 19:12:25 +0400 | From | Alexey Brodkin <> | Subject | Re: [PATCH] drivers/block/xsysace - replace in(out)_8/in(out)_be16/in(out)_le16 with generic iowrite(read)8/16(be) |
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On 02/07/2013 06:51 PM, Grant Likely wrote: > On Thu, Feb 7, 2013 at 2:39 PM, Grant Likely <grant.likely@secretlab.ca> wrote: >> On Wed, Feb 6, 2013 at 9:35 PM, Benjamin Herrenschmidt >> <benh@kernel.crashing.org> 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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