[PATCH] ata: ahci: Enable/Disable ATA Staggered Spin-up by default

Eric Curtin
2022-09-19T11:17:01Z

On some kernels tuned for performance, you want to always favour
spin-up time versus power draw. This adds the ability to always favour
spin-up time by default (disabling Staggered Spin-up favours
performance, rather than power draw).

Regardless of whether this is enabled or disabled the
libahci.ignore_sss option will override any kernel config.

Signed-off-by: Eric Curtin <ecurtin@redhat.com>
---
drivers/ata/Kconfig | 15 +++++++++++++++
drivers/ata/libahci.c | 2 +-
2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 1c9f4fb2595d..36b11fbcf644 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -67,6 +67,21 @@ config ATA_FORCE

If unsure, say Y.

+config ATA_SSS
+ bool "Enable ATA Staggered Spin-up by default"
+ default y
+ help
+ This option denotes whether Staggered Spin-up capability on
+ storage controllers is used. Staggered Spin-up reduces
+ peak power draw, but decreases performance. If this config is
+ set to N, Staggered Spin-up capability will be ignored by
+ default.
+
+ This can be overridden by using the kernel argument
+ libahci.ignore_sss.
+
+ If unsure, say Y.
+
config ATA_ACPI
bool "ATA ACPI Support"
depends on ACPI
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index cf8c7fd59ada..b7b573d47fda 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -33,7 +33,7 @@
#include "libata.h"

static int ahci_skip_host_reset;
-int ahci_ignore_sss;
+int ahci_ignore_sss = !IS_ENABLED(CONFIG_ATA_SSS);
EXPORT_SYMBOL_GPL(ahci_ignore_sss);

module_param_named(skip_host_reset, ahci_skip_host_reset, int, 0444);
--
2.37.3