[PATCH] [V2] ata: libata: add workaround to flip LPM during suspend/resume

[Koba Ko <koba.ko@canonical.com>]

Due to TigerLake/Adler Lake AHCI controller's LPM regression,
can't apply LPM on TigerLake/AdlerLake AHCI controller.

Add a workaround to flip LPM during suspend/resume.
When suspneding, apply LPM on TigerLake/AdlerLake AHCI.
Restore it to target_lpm_policy after resuming.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217775
Signed-off-by: Koba Ko <koba.ko@canonical.com>
---
V2: 
* remove the unused declarations
* add a condition for ATA_LFLAG_NO_LPM_RECOVER during suspned/resume
---
 drivers/ata/ahci.c      | 27 +++++++++++++++++++++++++++
 drivers/ata/libata-eh.c | 10 ++++++++++
 include/linux/libata.h  |  1 +
 3 files changed, 38 insertions(+)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 02503e903e4a8..658fac695adf1 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1025,6 +1025,30 @@ static void ahci_p5wdh_workaround(struct ata_host *host)
 		ap->link.flags |= ATA_LFLAG_NO_SRST | ATA_LFLAG_ASSUME_ATA;
 	}
 }
+/*
+ * Intel TGL/ADL workaround, when suspending, put port into LPM,
+ * recover to max power after resuming.
+ */
+static void ahci_intel_ahci_workaround(struct ata_host *host)
+{
+	struct pci_dev *pdev = to_pci_dev(host->dev);
+	int i;
+	static const struct pci_device_id ids[] = {
+		{ PCI_VDEVICE(INTEL, 0xa0d3)}, /* Tiger Lake UP{3,4} AHCI */
+		{ PCI_VDEVICE(INTEL, 0x7ae2)}, /* Alder Lake AHCI*/
+		{}
+	};
+
+	dev_info(&pdev->dev, "enabling Intel AHCI workaround\n");
+
+	if (pci_match_id(ids, pdev)) {
+		for (i = 0; i < host->n_ports; i++) {
+			struct ata_port *ap = host->ports[i];
+
+			ap->flags |= ATA_LFLAG_NO_LPM_RECOVER;
+		}
+	}
+}
 
 /*
  * Macbook7,1 firmware forcibly disables MCP89 AHCI and changes PCI ID when
@@ -1905,6 +1929,9 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	/* apply workaround for ASUS P5W DH Deluxe mainboard */
 	ahci_p5wdh_workaround(host);
 
+	/* apply workaround for Intel AHCI */
+	ahci_intel_ahci_workaround(host);
+
 	/* apply gtf filter quirk */
 	ahci_gtf_filter_workaround(host);
 
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 159ba6ba19ebb..0743a9986a5ac 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -4000,6 +4000,12 @@ static void ata_eh_handle_port_suspend(struct ata_port *ap)
 	int rc = 0;
 	struct ata_device *dev;
 
+	if (!!(ap->flags & ATA_LFLAG_NO_LPM_RECOVER))
+		ata_for_each_dev(dev, &ap->link, ENABLED) {
+			ata_eh_set_lpm(&ap->link, ATA_LPM_MED_POWER_WITH_DIPM, &dev);
+		}
+
+
 	/* are we suspending? */
 	spin_lock_irqsave(ap->lock, flags);
 	if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
@@ -4087,6 +4093,10 @@ static void ata_eh_handle_port_resume(struct ata_port *ap)
 	if (ap->ops->port_resume)
 		ap->ops->port_resume(ap);
 
+	if (!!(ap->flags & ATA_LFLAG_NO_LPM_RECOVER))
+		ata_for_each_dev(dev, &ap->link, ENABLED) {
+			ata_eh_set_lpm(&ap->link, ap->target_lpm_policy, &dev);
+		}
 	/* tell ACPI that we're resuming */
 	ata_acpi_on_resume(ap);
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 52d58b13e5eee..e720fed6dbd7f 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -147,6 +147,7 @@ enum {
 	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_DEBOUNCE_DELAY = (1 << 11), /* no debounce delay on link resume */
+	ATA_LFLAG_NO_LPM_RECOVER = (1 << 12), /* disable LPM on this link */
 
 	/* struct ata_port flags */
 	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */
-- 
2.25.1