From 31cc23b34913bc173680bdc87af79e551bf8cc0d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 23 Sep 2007 13:14:12 +0900 Subject: libata-pmp-prep: implement ops->qc_defer() Controllers which support PMP have various restrictions on which combinations of commands are allowed to what number of devices concurrently. This patch implements ops->qc_defer() which determines whether a qc can be issued at the moment or should be deferred. If the function returns ATA_DEFER_LINK, the qc will be deferred until a qc completes on the link. If ATA_DEFER_PORT, until a qc completes on any link. The defer conditions are advisory and in general ATA_DEFER_LINK can be considered as lower priority deferring than ATA_DEFER_PORT. ops->qc_defer() replaces fixed ata_scmd_need_defer(). For standard NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented. ahci and sata_sil24 are converted to use ata_std_qc_defer(). ops->qc_defer() is heavier than the original mechanism because full qc is prepped before determining to defer it, but various information is needed to determine defer conditinos and fully translating a qc is the only way to supply such information in generic manner. IMHO, this shouldn't cause any noticeable performance issues as * for most cases deferring occurs rarely (except for NCQ-aware cmd-switching PMP) * translation itself isn't that expensive * once deferred the command won't be repeated until another command completes which usually is a very long time cpu-wise. Signed-off-by: Tejun Heo Signed-off-by: Jeff Garzik --- include/linux/libata.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/libata.h') diff --git a/include/linux/libata.h b/include/linux/libata.h index c3820f105ff..b0d4ca0d27b 100644 --- a/include/linux/libata.h +++ b/include/linux/libata.h @@ -272,6 +272,10 @@ enum { /* ering size */ ATA_ERING_SIZE = 32, + /* return values for ->qc_defer */ + ATA_DEFER_LINK = 1, + ATA_DEFER_PORT = 2, + /* desc_len for ata_eh_info and context */ ATA_EH_DESC_LEN = 80, @@ -639,6 +643,7 @@ struct ata_port_operations { void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int); + int (*qc_defer) (struct ata_queued_cmd *qc); void (*qc_prep) (struct ata_queued_cmd *qc); unsigned int (*qc_issue) (struct ata_queued_cmd *qc); @@ -824,6 +829,7 @@ extern void ata_data_xfer(struct ata_device *adev, unsigned char *buf, unsigned int buflen, int write_data); extern void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf, unsigned int buflen, int write_data); +extern int ata_std_qc_defer(struct ata_queued_cmd *qc); extern void ata_dumb_qc_prep(struct ata_queued_cmd *qc); extern void ata_qc_prep(struct ata_queued_cmd *qc); extern void ata_noop_qc_prep(struct ata_queued_cmd *qc); -- cgit v1.2.3