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Commit e39b2bb3 authored Jan 07, 2016 by Danesh Petigara Committed by Tejun Heo Jan 08, 2016

libata: skip debounce delay on link resume



The link resume logic uses a 200msec delay while debouncing
the SControl register. The rationale behind that delay is
to accommodate some PHYs that behave badly if their SStatus/
SControl registers are pounded immediately on resume.
The Broadcom STB SATA PHY does not seem to have this issue.
This patch introduces a new link flag that allows platforms
to skip the debounce delay if it isn't needed.

Signed-off-by: Danesh Petigara <dpetigara@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 6ca92dd7

drivers/ata/ahci_brcmstb.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -85,6 +85,7 @@ struct brcm_ahci_priv {

		static const struct ata_port_info ahci_brcm_port_info = {
		.flags = AHCI_FLAG_COMMON \| ATA_FLAG_NO_DIPM,
		.link_flags = ATA_LFLAG_NO_DB_DELAY,
		.pio_mask = ATA_PIO4,
		.udma_mask = ATA_UDMA6,
		.port_ops = &ahci_platform_ops,

drivers/ata/libata-core.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -3598,6 +3598,7 @@ int sata_link_resume(struct ata_link link, const unsigned long params,
		* immediately after resuming. Delay 200ms before
		* debouncing.
		*/
		if (!(link->flags & ATA_LFLAG_NO_DB_DELAY))
		ata_msleep(link->ap, 200);

		/* is SControl restored correctly? */

include/linux/libata.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -205,6 +205,7 @@ enum {
		ATA_LFLAG_NO_LPM = (1 << 8), /* disable LPM on this link */
		ATA_LFLAG_RST_ONCE = (1 << 9), /* limit recovery to one reset */
		ATA_LFLAG_CHANGED = (1 << 10), /* LPM state changed on this link */
		ATA_LFLAG_NO_DB_DELAY = (1 << 11), /* no debounce delay on link resume */

		/* struct ata_port flags */
		ATA_FLAG_SLAVE_POSS = (1 << 0), /* host supports slave dev */