Hi,

On Monday 28 February 2005 16:24, Tejun Heo wrote:

  Hi,

Bartlomiej Zolnierkiewicz wrote:

quoted

On Sunday 27 February 2005 08:36, Tejun Heo wrote:

quoted

Hello, Bartlomiej.

This patch should be modified to use flagged taskfile if the
task_end_request_fix patch isn't applied.  As non-flagged taskfile
won't return valid result registers, TASK ioctl users won't get the
correct register output.

Nope, it works just fine because REQ_DRIVE_TASK used only
no-data protocol, please check task_no_data_intr().

  Sorry, I missed that.  IDE really has a lot of ways to finish a 
command, doesn't it?  hdio.txt is gonna look ugly. :-)

Yep but it was a lot more "fun" when there were three PIO codepaths. ;-)

hdio.txt doesn't need to know about driver internals so no problem here.

quoted

quoted

IMHO, this flag-to-get-result-registers thing is way too subtle.  How
about keeping old behavior by just not copying out register outputs in
ide_taskfile_ioctl() in applicable cases instead of not reading
registers when ending commands?  That is, unless there's some
noticeable performance impacts I'm not aware of.

This would miss whole point of not _reading_ these registers (IO is slow).
IMHO new flags denoting {in,out} registers should be added (to <linux/ata.h>
to share them with libata) so new code can be sane and old flags would map
on new flags when needed.

  Please do it.

  Or, let me know what you have in mind (added fields, flag names, 
etc...); then, I'll do it.  I think we also need to hear Jeff's opinion 
as things need to be added to ata.h.

I was thinking about:

* adding ATA_TFLAG_{IN,OUT}_xxx flags (there is enough free
  place for all flags in ->flags field of struct ata_taskfile)
* teaching flagged_taskfile() about these flags and mapping ->tf_out_flags
  onto ATA_TFLAG_OUT_xxx (simple mapping no need to move ->tf_out_flags
  to ide_taskfile_ioctl() etc. - no risk of breaking something)
* moving flagged taskfile writing to ide_tf_load_discrete() helper
* adding ide_tf_read_discrete() helper for use by ide_end_drive_cmd()
  and mapping ->tf_in_flags onto ATA_TFLAG_IN_xxx (ditto)

If you like this plan feel free to implement it.
I'm also open for better ideas, comments etc.

Bartlomiej