linux-kernel - Re: [PATCH] ata: Kconfig: Update SATA_LPM

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Message-ID: <b9dc8838-1272-5c7e-121d-768e7feed290@opensource.wdc.com>
Date:   Mon, 28 Mar 2022 09:37:40 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     "Limonciello, Mario" <Mario.Limonciello@....com>,
        Christoph Hellwig <hch@...radead.org>
Cc:     "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" 
        <linux-ide@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ata: Kconfig: Update SATA_LPM_POLICY default to "3"

On 3/25/22 00:09, Limonciello, Mario wrote:
> [Public]
> 
>> -----Original Message-----
>> From: Christoph Hellwig <hch@...radead.org>
>> Sent: Thursday, March 24, 2022 10:05
>> To: Limonciello, Mario <Mario.Limonciello@....com>
>> Cc: Damien Le Moal <damien.lemoal@...nsource.wdc.com>; open
>> list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers) <linux-
>> ide@...r.kernel.org>; open list <linux-kernel@...r.kernel.org>
>> Subject: Re: [PATCH] ata: Kconfig: Update SATA_LPM_POLICY default to "3"
>>
>> What about just reverting the rename of the config symbol?
>> It is a bit misleadinḑ, but so are many other option nams.  And they
>> really aren't the user interface anyway, the help text and description
>> are the main user interface and can be changed at will.
> 
> It was the rename that prompted us to give it a closer look.
> I think this patch should to change the default should happen either way.
> 
> If Damien or Linus wants to revert the rename, that's fine with me, but if
> we land this patch then I think it should serve the intent of most people and
> distros.

I am OK with the change of the default value to 3 since this is what most
distros have today anyway. Nevertheless, I think we should fallback on the
safe side with this and also revert the config name back to
CONFIG_SATA_LPM_MOBILE_POLICY to avoid any unintended side effects.

Please send a v2 with that rename and the default value change. As
Christoph suggested, the config option help text can be broader than what
the name suggests. I am thinking of something like this:

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index f27b12ba2ce7..ee3f96b5be70 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -125,14 +125,16 @@ config SATA_AHCI

 	  If unsure, say N.

-config SATA_LPM_POLICY
+config SATA_MOBILE_LPM_POLICY
 	int "Default SATA Link Power Management policy for low power chipsets"
 	range 0 4
-	default 0
+	default 3
 	depends on SATA_AHCI
 	help
 	  Select the Default SATA Link Power Management (LPM) policy to use
-	  for chipsets / "South Bridges" designated as supporting low power.
+	  for chipsets / "South Bridges" supporting low-power modes. Such
+	  chipsets are typically found on most laptops but desktops and
+	  servers now also widely use chipsets with low power modes support.

 	  The value set has the following meanings:
 		0 => Keep firmware settings



-- 
Damien Le Moal
Western Digital Research