libata-core: Document some limits/assumptions about ID_ATA
Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
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@ -1618,6 +1618,9 @@ static u32 ata_pio_mask_no_iordy(const struct ata_device *adev)
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* devices. This function also issues ATA_CMD_INIT_DEV_PARAMS
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* for pre-ATA4 drives.
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*
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* FIXME: ATA_CMD_ID_ATA is optional for early drives and right
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* now we abort if we hit that case.
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*
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* LOCKING:
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* Kernel thread context (may sleep)
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*
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@ -1745,10 +1748,13 @@ int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
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/*
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* The exact sequence expected by certain pre-ATA4 drives is:
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* SRST RESET
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* IDENTIFY
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* INITIALIZE DEVICE PARAMETERS
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* IDENTIFY (optional in early ATA)
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* INITIALIZE DEVICE PARAMETERS (later IDE and ATA)
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* anything else..
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* Some drives were very specific about that exact sequence.
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*
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* Note that ATA4 says lba is mandatory so the second check
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* shoud never trigger.
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*/
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if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
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err_mask = ata_dev_init_params(dev, id[3], id[6]);
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