linux-kernel - Re: SATA link power management issues

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Message-ID: <2356903.cA2H5W8V2D@xps13>
Date:	Mon, 20 Apr 2015 22:02:12 +0200
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-ide@...r.kernel.org, tj@...nel.org, stripathi@....com
Subject: Re: SATA link power management issues

On Sunday 22 February 2015 21:53:35 Gabriele Mazzotta wrote:
> Hi,
> 
> It seems that the following patch prevents errors when the policy is
> changed. Could anybody explain why?
> 
> Thanks,
> Gabriele
> 
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 61a9c07..38d39f7 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -1708,7 +1708,10 @@ static void ahci_handle_port_interrupt(struct ata_port *ap,
>  		status &= ~PORT_IRQ_BAD_PMP;
>  
>  	/* if LPM is enabled, PHYRDY doesn't mean anything */
> -	if (ap->link.lpm_policy > ATA_LPM_MAX_POWER) {
> +	if (ap->link.lpm_policy > ATA_LPM_MAX_POWER ||
> +	    ap->link.flags & ATA_LFLAG_CHANGED) {
> +		if (ap->link.flags & ATA_LFLAG_CHANGED)
> +			ap->link.flags &= ~ATA_LFLAG_CHANGED;
>  		status &= ~PORT_IRQ_PHYRDY;
>  		ahci_scr_write(&ap->link, SCR_ERROR, SERR_PHYRDY_CHG);
>  	}
> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> index d2029a4..e8f965c 100644
> --- a/drivers/ata/libata-eh.c
> +++ b/drivers/ata/libata-eh.c
> @@ -3489,6 +3489,8 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>  		}
>  	}
>  
> +	link->flags |= ATA_LFLAG_CHANGED;
> +
>  	return 0;
>  
>  fail:
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index fc03efa..5abf5f2 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -205,6 +205,7 @@ enum {
>  	ATA_LFLAG_SW_ACTIVITY	= (1 << 7), /* keep activity stats */
>  	ATA_LFLAG_NO_LPM	= (1 << 8), /* disable LPM on this link */
>  	ATA_LFLAG_RST_ONCE	= (1 << 9), /* limit recovery to one reset */
> +	ATA_LFLAG_CHANGED	= (1 << 10),
>  
>  	/* struct ata_port flags */
>  	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */

Hi,

did anyone looked at the above change?

Thanks,
Gabriele
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