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Message-ID: <ca1a7c99-e579-d314-0f09-ceca1b560d4a@redhat.com>
Date: Thu, 19 Jul 2018 15:13:40 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
tj@...nel.org
Cc: linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
alan.cox@...el.com, Mario.Limonciello@...l.com, rjw@...ysocki.net
Subject: Re: [RFC PATCH v2 1/2] ata: ahci: Support state with min power and
Partial low power state
Hi,
On 13-07-18 17:06, Srinivas Pandruvada wrote:
> Hi Hans,
> On Fri, 2018-07-13 at 11:08 +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 13-07-18 00:27, Srinivas Pandruvada wrote:
>>> Currently when min_power policy is selected, the partial low power
>>> state
>>> is not entered and link will try aggressively enter to only slumber
>>> state.
>>> Add a new policy which still enable DEVSLP but also try to enter
>>> partial
>>> low power state.
>>>
>>> For information the difference between partial and slumber
>>> Partial – PHY logic is powered up, and in a reduced power state.
>>> The link
>>> PM exit latency to active state maximum is 10 ns.
>>> Slumber – PHY logic is powered up, and in a reduced power state.
>>> The link
>>> PM exit latency to active state maximum is 10 ms.
>>> Devslp – PHY logic is powered down. The link PM exit latency from
>>> this
>>> state to active state maximum is 20 ms, unless otherwise specified
>>> by
>>> DETO.
>>>
>>> Suggested-by: Hans de Goede <hdegoede@...hat.com>
>>> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel
>>> .com>
>>
>> You got this the wrong way around, when ALP
> You mean ASP, as per spec in section 3.3.7 of the spec.
>
>> is not set you only get
>> partial,
> Not exactly.
> It means that the system will try to enter aggressively partial . I
> have seen slumber residency also when this is reset. When "set" you
> don't see any any partial. But when you reset you see both. So based on
> idle duration link will transition from partial to slumber even if "not
> set".
>
>> the ALP bit is active high, not active low as your commit
>> suggests. So the name of the new policy should be
>> min_power_without_asp.
>
>
> The policy name I am suggesting is not the actual bit value of ASP (I
> interpreted ASP as name for partial), but whether you will get to
> partial or not. So I think it is better to rename to
> "min_power_with_partial". User should not have to worry about the bit
> value.
>
>
> So user will see with the rename from "min_power_with_asp" to
> "min_power_with_partial":
>
> #cat /sys/class/scsi_host/host*/link_power_management_policy
> min_power_with_partial
> min_power_with_partial
> min_power_with_partial
>
> Output of test (You will see both partial and slumber)
>
> SATA LPM Summary - Sampled: Residency (Percentage)
> Disk Name , Off (%), Active (%), Partial (%), Slumber (%), Devsleep (%), Other (%), Uninitialized (%)
> --------- , -------, ----------, -----------, -----------, ------------, ---------, -----------------
> INTEL SSDSCKJF180A5, 0.0 , 4.6 , 13.1 , 30.3 , 52.0 , 0.0 , 0.0
>
> SATA LPM Summary - Sampled: Counts
> Disk Name , Off, Active, Partial, Slumber, Devsleep, Other, Uninitialized
> --------- , ---, ------, -------, -------, --------, -----, -------------
> INTEL SSDSCKJF180A5, 0 , 9 , 27 , 60 , 103 , 0 , 0
>
>
> # cat /sys/class/scsi_host/host*/link_power_management_policy
> min_power
> min_power
> min_power
>
> Output of test (You will see only slumber)
>
> SATA LPM Summary - Sampled: Residency (Percentage)
> Disk Name , Off (%), Active (%), Partial (%), Slumber (%), Devsleep (%), Other (%), Uninitialized (%)
> --------- , -------, ----------, -----------, -----------, ------------, ---------, -----------------
> INTEL SSDSCKJF180A5, 0.0 , 6.8 , 0.0 , 53.8 , 39.3 , 0.0 , 0.0
>
> SATA LPM Summary - Sampled: Counts
> Disk Name , Off, Active, Partial, Slumber, Devsleep, Other, Uninitialized
> --------- , ---, ------, -------, -------, --------, -----, -------------
> INTEL SSDSCKJF180A5, 0 , 11 , 0 , 107 , 76 , 0 , 0
Ah, I see thank you for clarifying that. Yes I agree that
min_power_with_partial is the best name for the new policy.
For the next version do not forget to make the overriding of the
lpm policy a per host thing, rather then directly overriding the
global value as I mentioned in a previous mail.
One other thing is to NOT override the policy if it is set on
the kernel-commandline, which I believe will require setting the
global value to -1 and only set another value if the global value
is not -1 (using you settings where applicable and falling back
to CONFIG_SATA_MOBILE_LPM_POLICY where not applicable).
Regards,
Hans
>>> ---
>>> drivers/ata/libahci.c | 6 +++++-
>>> drivers/ata/libata-core.c | 1 +
>>> drivers/ata/libata-scsi.c | 1 +
>>> include/linux/libata.h | 3 ++-
>>> 4 files changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
>>> index 511fb67f363d..8cf2cf49537d 100644
>>> --- a/drivers/ata/libahci.c
>>> +++ b/drivers/ata/libahci.c
>>> @@ -799,8 +799,11 @@ static int ahci_set_lpm(struct ata_link *link,
>>> enum ata_lpm_policy policy,
>>> return 0;
>>> } else {
>>> cmd |= PORT_CMD_ALPE;
>>> +
>>> if (policy == ATA_LPM_MIN_POWER)
>>> cmd |= PORT_CMD_ASP;
>>> + else if (policy ==
>>> ATA_LPM_MIN_POWER_WITH_ASP)
>>> + cmd &= ~PORT_CMD_ASP;
>>>
>>> /* write out new cmd value */
>>> writel(cmd, port_mmio + PORT_CMD);
>>> @@ -811,7 +814,8 @@ static int ahci_set_lpm(struct ata_link *link,
>>> enum ata_lpm_policy policy,
>>> if ((hpriv->cap2 & HOST_CAP2_SDS) &&
>>> (hpriv->cap2 & HOST_CAP2_SADM) &&
>>> (link->device->flags & ATA_DFLAG_DEVSLP)) {
>>> - if (policy == ATA_LPM_MIN_POWER)
>>> + if (policy == ATA_LPM_MIN_POWER ||
>>> + policy == ATA_LPM_MIN_POWER_WITH_ASP)
>>> ahci_set_aggressive_devslp(ap, true);
>>> else
>>> ahci_set_aggressive_devslp(ap, false);
>>> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
>>> index cc71c63df381..245a59e6cb18 100644
>>> --- a/drivers/ata/libata-core.c
>>> +++ b/drivers/ata/libata-core.c
>>> @@ -3970,6 +3970,7 @@ int sata_link_scr_lpm(struct ata_link *link,
>>> enum ata_lpm_policy policy,
>>> scontrol |= (0x6 << 8);
>>> break;
>>> case ATA_LPM_MED_POWER_WITH_DIPM:
>>> + case ATA_LPM_MIN_POWER_WITH_ASP:
>>> case ATA_LPM_MIN_POWER:
>>> if (ata_link_nr_enabled(link) > 0)
>>> /* no restrictions on LPM transitions */
>>> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
>>> index aad1b01447de..2d683db50ceb 100644
>>> --- a/drivers/ata/libata-scsi.c
>>> +++ b/drivers/ata/libata-scsi.c
>>> @@ -110,6 +110,7 @@ static const char *ata_lpm_policy_names[] = {
>>> [ATA_LPM_MAX_POWER] = "max_performance",
>>> [ATA_LPM_MED_POWER] = "medium_power",
>>> [ATA_LPM_MED_POWER_WITH_DIPM] =
>>> "med_power_with_dipm",
>>> + [ATA_LPM_MIN_POWER_WITH_ASP] =
>>> "min_power_with_asp",
>>> [ATA_LPM_MIN_POWER] = "min_power",
>>> };
>>>
>>> diff --git a/include/linux/libata.h b/include/linux/libata.h
>>> index 32f247cb5e9e..1e154f1f7e8f 100644
>>> --- a/include/linux/libata.h
>>> +++ b/include/linux/libata.h
>>> @@ -523,7 +523,8 @@ enum ata_lpm_policy {
>>> ATA_LPM_MAX_POWER,
>>> ATA_LPM_MED_POWER,
>>> ATA_LPM_MED_POWER_WITH_DIPM, /* Med power + DIPM as win
>>> IRST does */
>>> - ATA_LPM_MIN_POWER,
>>> + ATA_LPM_MIN_POWER_WITH_ASP, /* Min Power + partial and
>>> slumber */
>>> + ATA_LPM_MIN_POWER, /* Min power + no partial (slumber
>>> only) */
>>> };
>>>
>>> enum ata_lpm_hints {
>>>
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