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

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Date:   Fri, 22 Apr 2022 17:57:19 +0800
From:   RunaGuo-oc <RunaGuo-oc@...oxin.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Mario Limonciello" <mario.limonciello@....com>,
        Cobe Chen <CobeChen@...oxin.com>, Tim Guo <TimGuo@...oxin.com>,
        TonyW Wang <TonyWWang@...oxin.com>,
        Leo Liu <LeoLiu@...oxin.com>
Subject: Re: [PATCH 1/2] ahci: Add PhyRdy Change control on actual LPM
 capability

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@...oxin.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 */
>