linux-kernel - Re: [REGRESSION] libata: SATA LPM forcibly disabled on Intel Jasper Lake since Linux 6.13

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Message-ID: <37a2d604-6c20-4913-ad1a-15e727df8a3d@kernel.org>
Date: Mon, 15 Dec 2025 10:44:48 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Bernard Drozd <bernid@...eria.pl>, linux-ide@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Niklas Cassel <cassel@...nel.org>
Subject: Re: [REGRESSION] libata: SATA LPM forcibly disabled on Intel Jasper
 Lake since Linux 6.13

On 12/15/25 00:26, Bernard Drozd wrote:
> Hello,
> 
> I am reporting a power-management regression in libata affecting Intel 
> Jasper Lake platforms, introduced after Linux 6.12.
> 
> Hardware:
> - CPU / SoC: Intel Jasper Lake (Elkhart Lake class)
> - SATA controller: Intel Jasper Lake SATA AHCI Controller (PCI ID 8086:4d03)

Byt the way, I see this:

ahci.c: /* Elkhart Lake IDs 0x4b60 & 0x4b62 https://sata-io.org/product/8803 not
tested yet */
ahci.c: { PCI_VDEVICE(INTEL, 0x4b63), board_ahci_pcs_quirk }, /* Elkhart Lake
AHCI */

So the same "Elkhart Lake", but different PCI ID. Looking at PCI IDs databases,
I do not find anything with ID 8086:4d03. Can you please check your PCI ID ?

Though board_ahci_pcs_quirk does not disable LPM...


> - Drives tested: SATA SSD + SATA HDD (multiple vendors)
> - Distribution: Debian 13 (Trixie)
> - Kernel versions tested:
>    - 6.12.x  → OK
>    - 6.17.x  → REGRESSION
> 
> Problem description:
> Since kernel >= 6.13, SATA Link Power Management (LPM) is forcibly disabled.
> The sysfs interface still exists but only reports:
> 
>    /sys/class/scsi_host/host*/link_power_management_policy = max_performance
> 
> Attempts to change it fail silently or are ignored:
> 
> echo 'med_power_with_dipm' > 
> '/sys/class/scsi_host/host0/link_power_management_policy'
> echo 'med_power_with_dipm' > 
> '/sys/class/scsi_host/host1/link_power_management_policy'
> 
> This worked correctly on kernel 6.12.x and earlier.
> 
> Observed effects:
> - SATA devices never enter partial/slumber
> - CPU package C-states are limited (system mostly stuck in PC2 (before 
> the change i had C10))
> - Idle power consumption increases by ~5 W
> - powertop shows SATA LPM tunables as permanently "Bad"
> 
> Relevant dmesg output (6.17.x):
>    ata1: SATA link power management disabled due to platform quirk
>    ata2: SATA link power management disabled due to platform quirk
> 
> This appears to be caused by the libata change disabling LPM on Intel 
> platforms
> without a per-platform whitelist. Jasper Lake does not exhibit 
> instability with
> LPM enabled and worked reliably on previous kernels.
> 
> Expectation:
> - Either re-enable LPM for Intel Jasper Lake
> - Or provide a kernel parameter to override the forced LPM disable
>    (e.g. libata.allow_lpm=1)
> 
> This regression significantly impacts low-power systems and fanless mini-PCs
> based on Jasper Lake.
> 
> Please let me know if additional logs or testing are needed.
> 
> Best regards,
> bern
> 
> 


-- 
Damien Le Moal
Western Digital Research