linux-kernel - [PATCH 2/2] ata: ahci: Protect users from setting policies their drives don't support

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Date:   Mon, 28 Feb 2022 15:33:02 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
CC:     "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" 
        <linux-ide@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        <hdegoede@...hat.com>,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH 2/2] ata: ahci: Protect users from setting policies their drives don't support

As the default low power policy applies to more chipsets and drives, it's
important to make sure that drives actually support the policy that a user
selected in their kernel configuration.

If the drive doesn't support slumber, don't let the default policies
dependent upon slumber (`min_power` or `min_power_with_partial`) affect the
disk.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
Changes from RFC v1 -> PATCH v1:
* Move the warning and protection from drives that don't support slumber further
  into the calling path.
 drivers/ata/libahci.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 0ed484e04fd6..9dee721ed1fe 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -785,7 +785,15 @@ static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 		pp->intr_mask &= ~PORT_IRQ_PHYRDY;
 		writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
 
-		sata_link_scr_lpm(link, policy, false);
+		if (policy >= ATA_LPM_MIN_POWER_WITH_PARTIAL &&
+		   !(hpriv->cap & HOST_CAP_SSC)) {
+			struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+
+			dev_warn(&pdev->dev,
+				 "This drive doesn't support slumber; ignoring SATA policy\n");
+		} else {
+			sata_link_scr_lpm(link, policy, false);
+		}
 	}
 
 	if (hpriv->cap & HOST_CAP_ALPM) {
-- 
2.34.1