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Commit 5e5c74a5 authored by Robert Hancock's avatar Robert Hancock Committed by Jeff Garzik
Browse files

sata_nv: delay on switching between NCQ and non-NCQ commands 



This patch appears to solve some problems with commands timing out in
cases where an NCQ command is immediately followed by a non-NCQ command
(or possibly vice versa). This is a rather ugly solution, but until we
know more about why this is needed, this is about all we can do.

Signed-off-by: default avatarRobert Hancock <hancockr@shaw.ca>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent cc075910

drivers/ata/sata_nv.c

+10 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ struct nv_adma_port_priv { 
	void __iomem *		gen_block;

	void __iomem *		notifier_clear_block;

	u8			flags;

	int			last_issue_ncq;

};



struct nv_host_priv {
@@ -1260,6 +1261,7 @@ static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc) 
{

	struct nv_adma_port_priv *pp = qc->ap->private_data;

	void __iomem *mmio = pp->ctl_block;

	int curr_ncq = (qc->tf.protocol == ATA_PROT_NCQ);



	VPRINTK("ENTER\n");
@@ -1274,6 +1276,14 @@ static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc) 
	/* write append register, command tag in lower 8 bits

	   and (number of cpbs to append -1) in top 8 bits */

	wmb();



	if(curr_ncq != pp->last_issue_ncq) {

	   	/* Seems to need some delay before switching between NCQ and non-NCQ

		   commands, else we get command timeouts and such. */

		udelay(20);

		pp->last_issue_ncq = curr_ncq;

	}



	writew(qc->tag, mmio + NV_ADMA_APPEND);



	DPRINTK("Issued tag %u\n",qc->tag);