Re: [RFC PATCH] libata-sff: Fix oops reported in kerneloops.org forpnp devices with no ctl

From: Jeff Garzik
Date: Thu May 29 2008 - 17:57:19 EST


Alan Cox wrote:
The Linusified version:

- Make ata_sff_altstatus private so nobody uses it by mistake
- Drop the 400nS delay from it

Add

ata_sff_irq_status - encapsulates the IRQ check logic

This function keeps the existing behaviour for altstatus using devices. I
actually suspect the logic was wrong before the changes but -rc isn't the
time to play with that

ata_sff_sync - ensure writes hit the device

Really we want an io* operation for 'is posted' eg ioisposted(ioaddr) so
that we can fix the nasty delay this causes on most systems.

- ata_sff_pause - 400nS delay

Ensure the command hit the device and delay 400nS

- ata_sff_dma_pause
Ensure the I/O hit the device and enforce an HDMA1:0 transition delay.
Requires altstatus register exists, BUG if not so we don't risk
corruption in MWDMA modes. (UDMA the checksum will save your backside in
theory)

The only other complication then is devices with their own handlers.
rb532 can use dma_pause but scc needs to access its own altstatus
register for internal errata workarounds so directly call the drivers own
altstatus function.

Signed-off-by: Alan Cox <alan@xxxxxxxxxx>

Honestly I think your first RFC PATCH (dated Thu, 29 May 2008 22:10:58 +0100) turned out better than this.

NO_ALTSTATUS is a bit ugly, don't you think?

In any case, based on a quick review I would certainly ack the first RFC PATCH.

Jeff




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