Hello.
Bartlomiej Zolnierkiewicz wrote:
Remove the bogus code pretending to set SW/MW DMA timings -- I wonder whether
its author really thought that he could achieve that wrtiting to BMIDE status
registers? Stop fiddling with the DMA capable bits in the speedproc() -- they
do not enable DMA, and are properly dealt with by the dma_host_{on,off} methods;
also, get rid of the duplicate reads/writes of UDIDETCRx registers, and do some
coding style and whitespace changes while at it...
Unfortunately, fixing the SW/MW DMA support would requre a major driver rewrite
along with some more fixing, so I'm putting it off...
Warning: this has been compile-tested only.
Worked fine on my SPARC Ultra5.
Correction: I was only looking for absence of errors when testing
this patch. However, later I found that this patch (version 1.42
of cmd64x.c) disabled DMA on my CMD646, dropping performance to
1/4th (from about 13MB/s to about 3.5MB/s according to hdparm -Tt).
That was expected behavior.
Here's the relevant kernel messages from before this patch:
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
CMD646: IDE controller at PCI slot 0000:01:03.0
CMD646: chipset revision 3
CMD646: chipset revision 0x03, MultiWord DMA Force Limited
The driver never supported UltraDMA on this revision, as indicated by that
message.
CMD646: 100% native mode on irq 14
ide0: BM-DMA at 0x1fe02c00020-0x1fe02c00027, BIOS settings: hda:pio, hdb:pio
ide1: BM-DMA at 0x1fe02c00028-0x1fe02c0002f, BIOS settings: hdc:pio, hdd:pio
Probing IDE interface ide0...
hda: ST320420A, ATA DISK drive
ide0 at 0x1fe02c00000-0x1fe02c00007,0x1fe02c0000a on irq 14
Probing IDE interface ide1...
hdc: CRD-8483B, ATAPI CD/DVD-ROM drive
ide1 at 0x1fe02c00010-0x1fe02c00017,0x1fe02c0001a on irq 14 (shared with ide0)
hda: max request size: 128KiB
hda: 39851760 sectors (20404 MB) w/2048KiB Cache, CHS=39535/16/63, (U)DMA
hda: cache flushes not supported
hda: hda1 hda2 hda3 hda4 hda5
With the patch the kernel messages are the same, except for the
3rd last line which becomes:
hda: 39851760 sectors (20404 MB) w/2048KiB Cache, CHS=39535/16/63
i.e., the (U)DMA indicator is gone.
Please revert this until the regression is fixed.
The intent of the patch was exactly to *remove* broken DMA support until
it's fixed (which requires more work). It only worked by chance -- because
MWDMA2 timings are the same as of PIO4. Have patience please.
It only worked by chance but it _worked_, especially for the usual case,
MWDMA2/PIO4 == all newer drives (despite writing 0x10 reserved bit of
BMIDESR0/1 for the master devices). I think I'll remove the patch for now.
Then I will protest. :-) This was *not* fixable all at once. And removing
it just because some users happen to have the *known buggy* (and so reduced to
MWDMA only) chips is a wrong thing to do.
PCI0643 would also suffer, to be precise.
OK, I'm not removing it but it needs (rather urgent) fixing.
To fix SWDMA/MWDMA properly isn't it enough to just call cmd64x_tune_pio()
from cmd64x_tune_chipset() to tune the corresponding PIO mode?
No, that wouldn't be a clean fix, just a kind of workaround -- it will
also change the address setup times (which is not quite desirable). I can
I see, how about:
* splitting off setup timing programming from program_drive_counts()
into separate function (setup timing is programmed into separate register)
Yes, it's on my todo list. But consider the amount of cleanup work I had
to do (and have in drafts still) for 2.6.21-rc1 -- if it really gets there
:-). And also, consider that currently I have a plenty of internal bugs to
fix besides IDE (and they're not as obvious as IDE ones).
* pushing ide_get_best_pio_mode() call to higher layers
[ cmd64x_tune_driver() only, it is not needed in cmd64x_tune_chipset() ]
Ehm, is it really there? I thought I left it in cmd64x_tune_pio() where
it's on its right place...
* calling new function setting setup timing from cmd64x_tune_drive()
and cmd64x_tune_chipset() (here for PIO modes only)
I ceratainly don't want to put this into cmd64x_tune_chipset() -- this
should be handled in cmd64x_tune_pio() still.
* calling cmd64x_tune_pio() fro SWDMA/MWDMA
Erm? Putting time-to-cycle converion into program_drive_counts() sound
like a better plan.
Would the above assembly into the proper SWDMA/MWDMA fix?
Not all items did make sense to me, sorry. :-)
compose such quickie in five minutes though.
I can wait some time for the proper fix but if you see that
it won't happen soon (week?) please send me this workaround.
I think it will happen in a week.
Thanks,
Bart
WBR, Sergei
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