[PATCH 0/2] ahci: Add some controls on actual LPM capability

[PATCH 0/2] ahci: Add some controls on actual LPM capability

[Runa Guo-oc]

On some platform, when OS enables LPM by default (eg, min_power),
then, PhyRdy Change cannot be detected if ahci supports no LPM;
DIPM Slumber request cannot be disallowed if ahci's CAP.PSC is
set to '1' and CAP.SSC is cleared to '0', which may cause ahci
to be an uncertain state (same for Partial).

In ahci spec, PhyRdy Change cannot coexist with LPM;
when CAP.PSC/SSC is cleared to '0', the PxSCTL.IPM
field must be programmed to disallow device initiated
Partial/Slumber request.

Adds suports to control these cases on actual LPM capability.

Runa Guo-oc (2):
  ahci: Add PhyRdy Change control on actual LPM capability
  ahci: Add PxSCTL.IPM control on actual LPM capability

 drivers/ata/ahci.c        |  9 +++++++++
 drivers/ata/libata-eh.c   |  4 ++++
 drivers/ata/libata-sata.c | 12 +++++++++++-
 include/linux/libata.h    |  4 ++++
 4 files changed, 28 insertions(+), 1 deletion(-)

-- 
2.7.4

[PATCH 1/2] ahci: Add PhyRdy Change control on actual LPM capability

[Runa Guo-oc]

On some platform, when OS enables LPM by default (eg, min_power),
then, PhyRdy Change cannot be detected if ahci supports no LPM.

In ahci spec, PhyRdy Change cannot coexist with LPM.

Adds support to control this case on actual LPM capability.

Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
---
 drivers/ata/ahci.c      | 9 +++++++++
 drivers/ata/libata-eh.c | 4 ++++
 include/linux/libata.h  | 4 ++++
 3 files changed, 17 insertions(+)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 397dfd2..03f0cb3 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1870,6 +1870,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	else
 		dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n");
 
+	if (hpriv->cap & HOST_CAP_PART)
+		host->flags |= ATA_HOST_PART;
+
+	if (hpriv->cap & HOST_CAP_SSC)
+		host->flags |= ATA_HOST_SSC;
+
+	if (hpriv->cap2 & HOST_CAP2_SDS)
+		host->flags |= ATA_HOST_DEVSLP;
+
 	if (pi.flags & ATA_FLAG_EM)
 		ahci_reset_em(host);
 
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 3307ed4..05b1043 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3246,6 +3246,10 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	unsigned int err_mask;
 	int rc;
 
+	/* if controller does not support lpm, then sets no LPM flags*/
+	if (!(ap->host->flags & (ATA_HOST_PART | ATA_HOST_SSC | ATA_HOST_DEVSLP)))
+		link->flags |= ATA_LFLAG_NO_LPM;
+
 	/* if the link or host doesn't do LPM, noop */
 	if (!IS_ENABLED(CONFIG_SATA_HOST) ||
 	    (link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 732de90..7a243f4 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -216,6 +216,10 @@ enum {
 	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
 	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
 
+	ATA_HOST_PART		= (1 << 4), /* Host support partial.*/
+	ATA_HOST_SSC		= (1 << 5), /* Host support slumber.*/
+	ATA_HOST_DEVSLP		= (1 << 6), /* Host support devslp.*/
+
 	/* bits 24:31 of host->flags are reserved for LLD specific flags */
 
 	/* various lengths of time */
-- 
2.7.4

[PATCH 2/2] ahci: Add PxSCTL.IPM control on actual LPM capability

[Runa Guo-oc]

On some platform, when OS enables LPM by default (eg, min_power),
then, DIPM slumber request cannot be disallowed if ahci's CAP.PSC
is set to '1' and CAP.SSC is cleared to '0', which may cause ahci
to be an uncertain state (same for Partial).

In ahci spec, when CAP.PSC/SSC is cleared to '0', the PxSCTL.IPM
field must be programmed to disallow device initiated Partial/
Slumber request.

Adds support to control this case on actual LPM capability.

Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
---
 drivers/ata/libata-sata.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index 7a5fe41..e6195cf 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -394,9 +394,19 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	case ATA_LPM_MED_POWER_WITH_DIPM:
 	case ATA_LPM_MIN_POWER_WITH_PARTIAL:
 	case ATA_LPM_MIN_POWER:
-		if (ata_link_nr_enabled(link) > 0)
+		if (ata_link_nr_enabled(link) > 0) {
 			/* no restrictions on LPM transitions */
 			scontrol &= ~(0x7 << 8);
+
+			/* if controller does not support partial, then disallows it,
+			 * the same for slumber
+			 */
+			if (!(link->ap->host->flags & ATA_HOST_PART))
+				scontrol |= (0x1 << 8);
+
+			if (!(link->ap->host->flags & ATA_HOST_SSC))
+				scontrol |= (0x2 << 8);
+		}
 		else {
 			/* empty port, power off */
 			scontrol &= ~0xf;
-- 
2.7.4

Re: [PATCH 1/2] ahci: Add PhyRdy Change control on actual LPM capability

[Damien Le Moal]

On 4/21/22 18:43, Runa Guo-oc wrote:
> On some platform, when OS enables LPM by default (eg, min_power),
> then, PhyRdy Change cannot be detected if ahci supports no LPM.

Do you mean "...if the ahci adapter does not support LPM." ?
If that is what you mean, then min_power should not be set. Mario has
patches to fix that.

> 
> In ahci spec, PhyRdy Change cannot coexist with LPM.
> 
> Adds support to control this case on actual LPM capability.
> 
> Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
> ---
>  drivers/ata/ahci.c      | 9 +++++++++
>  drivers/ata/libata-eh.c | 4 ++++
>  include/linux/libata.h  | 4 ++++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index 397dfd2..03f0cb3 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -1870,6 +1870,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	else
>  		dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n");
>  
> +	if (hpriv->cap & HOST_CAP_PART)
> +		host->flags |= ATA_HOST_PART;
> +
> +	if (hpriv->cap & HOST_CAP_SSC)
> +		host->flags |= ATA_HOST_SSC;
> +
> +	if (hpriv->cap2 & HOST_CAP2_SDS)
> +		host->flags |= ATA_HOST_DEVSLP;
> +
>  	if (pi.flags & ATA_FLAG_EM)
>  		ahci_reset_em(host);
>  
> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> index 3307ed4..05b1043 100644
> --- a/drivers/ata/libata-eh.c
> +++ b/drivers/ata/libata-eh.c
> @@ -3246,6 +3246,10 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>  	unsigned int err_mask;
>  	int rc;
>  
> +	/* if controller does not support lpm, then sets no LPM flags*/
> +	if (!(ap->host->flags & (ATA_HOST_PART | ATA_HOST_SSC | ATA_HOST_DEVSLP)))
> +		link->flags |= ATA_LFLAG_NO_LPM;
> +
>  	/* if the link or host doesn't do LPM, noop */
>  	if (!IS_ENABLED(CONFIG_SATA_HOST) ||
>  	    (link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index 732de90..7a243f4 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -216,6 +216,10 @@ enum {
>  	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
>  	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
>  
> +	ATA_HOST_PART		= (1 << 4), /* Host support partial.*/
> +	ATA_HOST_SSC		= (1 << 5), /* Host support slumber.*/
> +	ATA_HOST_DEVSLP		= (1 << 6), /* Host support devslp.*/
> +
>  	/* bits 24:31 of host->flags are reserved for LLD specific flags */
>  
>  	/* various lengths of time */


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH 2/2] ahci: Add PxSCTL.IPM control on actual LPM capability

[Damien Le Moal]

On 4/21/22 18:43, Runa Guo-oc wrote:
> On some platform, when OS enables LPM by default (eg, min_power),
> then, DIPM slumber request cannot be disallowed if ahci's CAP.PSC
> is set to '1' and CAP.SSC is cleared to '0', which may cause ahci
> to be an uncertain state (same for Partial).
> 
> In ahci spec, when CAP.PSC/SSC is cleared to '0', the PxSCTL.IPM
> field must be programmed to disallow device initiated Partial/
> Slumber request.
> 
> Adds support to control this case on actual LPM capability.

s/Adds/Add

Overall, I need to reread the specs to confirm all this.

> 
> Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
> ---
>  drivers/ata/libata-sata.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index 7a5fe41..e6195cf 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -394,9 +394,19 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>  	case ATA_LPM_MED_POWER_WITH_DIPM:
>  	case ATA_LPM_MIN_POWER_WITH_PARTIAL:
>  	case ATA_LPM_MIN_POWER:
> -		if (ata_link_nr_enabled(link) > 0)
> +		if (ata_link_nr_enabled(link) > 0) {
>  			/* no restrictions on LPM transitions */>  			scontrol &= ~(0x7 << 8);

Given that the added code below adds restrictions, this comment is
strange. Better change it to something like:

			/* Assume no restrictions on LPM transitions */

> +
> +			/* if controller does not support partial, then disallows it,
> +			 * the same for slumber
> +			 */

Please correctly format the comment and check the grammar. Some like below
is easier to read.

			/*
			 * If the controller does not support partial or
			 * slumber then disallow these transitions.
			 */

> +			if (!(link->ap->host->flags & ATA_HOST_PART))
> +				scontrol |= (0x1 << 8);
> +
> +			if (!(link->ap->host->flags & ATA_HOST_SSC))
> +				scontrol |= (0x2 << 8);
> +		}
>  		else {

Please do not leave this else here. Put it on the same line as the closing
bracket and enclose the below statements in brackets too.

>  			/* empty port, power off */
>  			scontrol &= ~0xf;

		} else {
			/* empty port, power off */
 			scontrol &= ~0xf;
		}


-- 
Damien Le Moal
Western Digital Research

Re: [PATCH 1/2] ahci: Add PhyRdy Change control on actual LPM capability

[RunaGuo-oc]

On 2022/4/21 18:39, Damien Le Moal wrote:
> On 4/21/22 18:43, Runa Guo-oc wrote:
>> On some platform, when OS enables LPM by default (eg, min_power),
>> then, PhyRdy Change cannot be detected if ahci supports no LPM.
> Do you mean "...if the ahci adapter does not support LPM." ?

Yes.

> If that is what you mean, then min_power should not be set.

Yes, I agree with you. But, as we know, link_power_management
is a user policy which can be modified, if some users are not
familiar with ahci spec, then the above case may happen.

>   Mario has patches to fix that.

  
Hmm. How to patch this case ?

>> In ahci spec, PhyRdy Change cannot coexist with LPM.
>>
>> Adds support to control this case on actual LPM capability.
>>
>> Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
>> ---
>>   drivers/ata/ahci.c      | 9 +++++++++
>>   drivers/ata/libata-eh.c | 4 ++++
>>   include/linux/libata.h  | 4 ++++
>>   3 files changed, 17 insertions(+)
>>
>> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
>> index 397dfd2..03f0cb3 100644
>> --- a/drivers/ata/ahci.c
>> +++ b/drivers/ata/ahci.c
>> @@ -1870,6 +1870,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>>   	else
>>   		dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n");
>>   
>> +	if (hpriv->cap & HOST_CAP_PART)
>> +		host->flags |= ATA_HOST_PART;
>> +
>> +	if (hpriv->cap & HOST_CAP_SSC)
>> +		host->flags |= ATA_HOST_SSC;
>> +
>> +	if (hpriv->cap2 & HOST_CAP2_SDS)
>> +		host->flags |= ATA_HOST_DEVSLP;
>> +
>>   	if (pi.flags & ATA_FLAG_EM)
>>   		ahci_reset_em(host);
>>   
>> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
>> index 3307ed4..05b1043 100644
>> --- a/drivers/ata/libata-eh.c
>> +++ b/drivers/ata/libata-eh.c
>> @@ -3246,6 +3246,10 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>>   	unsigned int err_mask;
>>   	int rc;
>>   
>> +	/* if controller does not support lpm, then sets no LPM flags*/
>> +	if (!(ap->host->flags & (ATA_HOST_PART | ATA_HOST_SSC | ATA_HOST_DEVSLP)))
>> +		link->flags |= ATA_LFLAG_NO_LPM;
>> +
>>   	/* if the link or host doesn't do LPM, noop */
>>   	if (!IS_ENABLED(CONFIG_SATA_HOST) ||
>>   	    (link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
>> diff --git a/include/linux/libata.h b/include/linux/libata.h
>> index 732de90..7a243f4 100644
>> --- a/include/linux/libata.h
>> +++ b/include/linux/libata.h
>> @@ -216,6 +216,10 @@ enum {
>>   	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
>>   	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
>>   
>> +	ATA_HOST_PART		= (1 << 4), /* Host support partial.*/
>> +	ATA_HOST_SSC		= (1 << 5), /* Host support slumber.*/
>> +	ATA_HOST_DEVSLP		= (1 << 6), /* Host support devslp.*/
>> +
>>   	/* bits 24:31 of host->flags are reserved for LLD specific flags */
>>   
>>   	/* various lengths of time */
>

Re: [PATCH 2/2] ahci: Add PxSCTL.IPM control on actual LPM capability

[RunaGuo-oc]

On 2022/4/21 18:53, Damien Le Moal wrote:
> On 4/21/22 18:43, Runa Guo-oc wrote:
>> On some platform, when OS enables LPM by default (eg, min_power),
>> then, DIPM slumber request cannot be disallowed if ahci's CAP.PSC
>> is set to '1' and CAP.SSC is cleared to '0', which may cause ahci
>> to be an uncertain state (same for Partial).
>>
>> In ahci spec, when CAP.PSC/SSC is cleared to '0', the PxSCTL.IPM
>> field must be programmed to disallow device initiated Partial/
>> Slumber request.
>>
>> Adds support to control this case on actual LPM capability.
> s/Adds/Add

Sorry, here should use 'Add' instead of 'Adds'.

> Overall, I need to reread the specs to confirm all this.

Ok.

>> Signed-off-by: Runa Guo-oc <RunaGuo-oc@zhaoxin.com>
>> ---
>>   drivers/ata/libata-sata.c | 12 +++++++++++-
>>   1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
>> index 7a5fe41..e6195cf 100644
>> --- a/drivers/ata/libata-sata.c
>> +++ b/drivers/ata/libata-sata.c
>> @@ -394,9 +394,19 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>>   	case ATA_LPM_MED_POWER_WITH_DIPM:
>>   	case ATA_LPM_MIN_POWER_WITH_PARTIAL:
>>   	case ATA_LPM_MIN_POWER:
>> -		if (ata_link_nr_enabled(link) > 0)
>> +		if (ata_link_nr_enabled(link) > 0) {
>>   			/* no restrictions on LPM transitions */>  			scontrol &= ~(0x7 << 8);
> Given that the added code below adds restrictions, this comment is
> strange. Better change it to something like:
>
> 			/* Assume no restrictions on LPM transitions */
>
>> +
>> +			/* if controller does not support partial, then disallows it,
>> +			 * the same for slumber
>> +			 */
> Please correctly format the comment and check the grammar. Some like below
> is easier to read.
>
> 			/*
> 			 * If the controller does not support partial or
> 			 * slumber then disallow these transitions.
> 			 */
>
>> +			if (!(link->ap->host->flags & ATA_HOST_PART))
>> +				scontrol |= (0x1 << 8);
>> +
>> +			if (!(link->ap->host->flags & ATA_HOST_SSC))
>> +				scontrol |= (0x2 << 8);
>> +		}
>>   		else {
> Please do not leave this else here. Put it on the same line as the closing
> bracket and enclose the below statements in brackets too.
>
>>   			/* empty port, power off */
>>   			scontrol &= ~0xf;
> 		} else {
> 			/* empty port, power off */
>   			scontrol &= ~0xf;
> 		}

  
I'll change it like below,
+		if (ata_link_nr_enabled(link) > 0) {
-			/* no restrictions on LPM transitions */
+			/* Assume no restrictions on LPM transitions */
			scontrol &= ~(0x7 << 8);
  
+			/*
+			 * If the controller does not support partial or
+			 * slumber then disallow these transitions.
+			 */

+			if (!(link->ap->host->flags & ATA_HOST_PART))
+				scontrol |= (0x1 << 8);
+
+			if (!(link->ap->host->flags & ATA_HOST_SSC))
+				scontrol |= (0x2 << 8);

		} else {
			/* empty port, power off */
  			scontrol &= ~0xf;
		}