Messages in this thread | | | Date | Fri, 19 Dec 2008 14:31:35 +0300 | From | Sergei Shtylyov <> | Subject | Re: [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O support properly |
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Hello.
Alan Cox wrote:
>> OTOH the current patch is safe even for 2.6.28 (based on years of experience >> with the check that we had in IDE subsystem) and will fix some libata drivers >> (pata_legacy, pata_qdi and pata_winbond) to use dword IO on >= ATA-2 devices. >> >> [ In reality this a regression fix for IDE -> libata conversion as it is a >> huge performance improvement for the above mentioned DMA-less drivers. ] >> > > The 32bit PIO support is already queued up and went to Jeff a while ago > so thats all in hand - its btw a big win on some suprising chipset cases > including Intel ICH chipsets. >
This is indeed strange...
>> Jeff, I would like to merge it through IDE tree since the other patch depends >> on it but if you want to go ahead and push it to Linus earlier feel free to >> do it (or I can include it into the next IDE fixes pull request if you like). >> > > Its still broken. You cannot use the version check for versions below 3. >
The word is reserved since ATA-2, and ata_id_major_version() should be returning 0 for pre-ATA-3 drives, so I don't know what else can be done here...
> I remain unconvinced we should be looking at it anywhere except specific > pure ISA cycle pass through hardware and thus it belongs as a helper for >
I'm still not getting how drive can support or not support "DWORD I/O" -- you certainly can't have 32-bit I/O cycle on ISA (only on EISA) and you certainly cannot translate 32-bit cycle to the ATA bus. I remember I had some hypotheses before but they turned out to be inconsistent.
> those drivers not as ata_has_mumble stuff as its not ATA - eide_* maybe. >
Indeed, already ATA-1 says that the word 48 is "includedfor backwards compatible VU use".
> Alan >
MBR, Sergei
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