Re: hwif->rw_disk() method

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Hello.

Alan wrote:

Alan/Bart/anybody, could you enlighten me why hwif->rw_disk() method came into being at all?

When you needed to wrap entire disk operations. The ->dma_ methods only
wrap DMA commands.

BTW, I've looked at the clock turnaround code both in drivers/ide/hpt366.c and drivers/ata/pata_hpt3x2n.c and compared it to the HighPoint driver and I'm dazed and confused (again?): contrary to what HighPoint does (I'm not sure they're still doing it at all due to confused nature of their drivers :-), Linux uses DPLL on reads and PCI clock on writes. The libata driver seem to have an explicit contradiction:

static int hpt3x2n_use_dpll(struct ata_port *ap, int reading)
{
        long flags = (long)ap->host->private_data;
        /* See if we should use the DPLL */
        if (reading == 0)
                return USE_DPLL;        /* Needed for write */
        if (flags & PCI66)
                return USE_DPLL;        /* Needed at 66Mhz */
        return 0;
}

static unsigned int hpt3x2n_qc_issue_prot(struct ata_queued_cmd *qc)
{
        struct ata_taskfile *tf = &qc->tf;
        struct ata_port *ap = qc->ap;
        int flags = (long)ap->host->private_data;

        if (hpt3x2n_pair_idle(ap)) {
                int dpll = hpt3x2n_use_dpll(ap, (tf->flags & ATA_TFLAG_WRITE));
                if ((flags & USE_DPLL) != dpll) {
                        if (dpll == 1)
                                hpt3x2n_set_clock(ap, 0x21);
                        else
                                hpt3x2n_set_clock(ap, 0x23);
                }
        }
        return ata_qc_issue_prot(qc);
}

ATA_TFLAG_WRITE indicates a write transfer (host-to-device) while hpt3x2n_use_dpll() contrarywise expects the read transfer indication. Comments?

WBR, Sergei
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