Jens Axboe wrote:
>> I think that should be feasible.. However, one problem is that 
>> slave_config only has access to the struct scsi_device and the 
>> ata_scsi_find_dev function to turn that into a struct ata_device isn't 
>> exported, which it would need to be in order to do anything useful 
>> inside the driver for slave_config. We could export it, or I suppose the 
>> other place we could do this handling would be postreset, as at that 
>> point we should know what kind of device is attached.. any comments?
> 
> What else do you need? From the scsi device, call the
> blk_queue_bounce_limit() on the queue tored in there. That shold be it.
> 
>> Also, how is the driver supposed to be setting the DMA mask for the SCSI 
>> device? I suppose blk_queue_bounce_limit would work, but it seems a bit 
>> odd to use block layer calls at the libata driver level.
> 
> That is the right thing to do.
> 
>> I also noticed that I'm still using the default 64KB libata dma_boundary 
>> value, this should be 4GB for ADMA mode (but fixed up back to the 
>> default if an ATAPI device is connected, same as with the DMA mask).
> 
> You can set that from the same location as the bounce limit.

OK, I've cut another patch (v4) which incorporates the auto-setting of 
the lower bounce limit and segment boundary when an ATAPI device is 
connected to the port. ATAPI was not actually tested as I don't have any 
ATAPI SATA devices. I also cleaned up a few other things such as 
handling failure to set the 64-bit DMA mask as well as using 
ata_port_printk where appropriate.

I think this resolves all of the outstanding comments and known issues.. 
as before, commenters, testers, and mergers are welcome :-)

This patch is against 2.6.19-rc2.

---

This patch adds support for ADMA mode on NVIDIA nForce4 (CK804/MCP04) 
SATA controllers to the sata_nv driver. Benefits of ADMA mode include:

-NCQ support
-Reduced CPU overhead (controller DMAs command information from memory 
instead of them being pushed in by the CPU)
-Full 64-bit DMA support

ADMA mode is disabled by default in this version. To enable ADMA on 
supported controllers, set the module parameter adma_enabled=1.

Signed-off-by: Robert Hancock <hancockr@shaw.ca>

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/