[PATCH 1/2] ata: ahci: Refactor ahci_broken_lpm()

[Niklas Cassel <cassel@kernel.org>]

Currently, the match table in ahci_broken_lpm() contains DMI BIOS dates
of BIOSes that are known to be working.

Having a list of known to be working versions is usually the wrong way to
do things (as this list could theoretically be infinite).

Refactor this match table to contain DMI BIOS dates of BIOSes that are
known to not be working, such that this list can be extended with BIOS
versions (for other boards) that are known to not be working, where there
is no good BIOS version (because all released versions are broken).

Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/ata/ahci.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 163ac909bd06..a6ce172fa928 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1411,27 +1411,39 @@ static bool ahci_broken_suspend(struct pci_dev *pdev)
 static bool ahci_broken_lpm(struct pci_dev *pdev)
 {
 	static const struct dmi_system_id sysids[] = {
-		/* Various Lenovo 50 series have LPM issues with older BIOSen */
+		/* Table contains DMI BIOS dates of BIOSes with broken LPM. */
 		{
 			.matches = {
 				DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 				DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X250"),
 			},
-			.driver_data = "20180406", /* 1.31 */
+			/*
+			 * 1.31, released 20180406, has working LPM, mark any
+			 * DMI BIOS date before that as broken.
+			 */
+			.driver_data = "20180405",
 		},
 		{
 			.matches = {
 				DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 				DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad L450"),
 			},
-			.driver_data = "20180420", /* 1.28 */
+			/*
+			 * 1.28, released 20180420, has working LPM, mark any
+			 * DMI BIOS date before that as broken.
+			 */
+			.driver_data = "20180419",
 		},
 		{
 			.matches = {
 				DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 				DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T450s"),
 			},
-			.driver_data = "20180315", /* 1.33 */
+			/*
+			 * 1.33, released 20180315, has working LPM, mark any
+			 * DMI BIOS date before that as broken.
+			 */
+			.driver_data = "20180314",
 		},
 		{
 			.matches = {
@@ -1439,12 +1451,14 @@ static bool ahci_broken_lpm(struct pci_dev *pdev)
 				DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad W541"),
 			},
 			/*
-			 * Note date based on release notes, 2.35 has been
-			 * reported to be good, but I've been unable to get
-			 * a hold of the reporter to get the DMI BIOS date.
-			 * TODO: fix this.
+			 * Note: according to release notes, version 2.35 has
+			 * working LPM, but we do not have the DMI BIOS date for
+			 * this version, so the date, 20180310, is based on the
+			 * release notes. Mark any DMI BIOS date before that as
+			 * broken.
+			 * TODO: find with date with DMI BIOS date.
 			 */
-			.driver_data = "20180310", /* 2.35 */
+			.driver_data = "20180309",
 		},
 		{ }	/* terminate list */
 	};
@@ -1458,7 +1472,7 @@ static bool ahci_broken_lpm(struct pci_dev *pdev)
 	dmi_get_date(DMI_BIOS_DATE, &year, &month, &date);
 	snprintf(buf, sizeof(buf), "%04d%02d%02d", year, month, date);
 
-	return strcmp(buf, dmi->driver_data) < 0;
+	return strcmp(buf, dmi->driver_data) <= 0;
 }
 
 static bool ahci_broken_online(struct pci_dev *pdev)
-- 
2.49.0