linux-kernel - Re: [PATCH v2] libata: disable forced PORTS

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Date:	Sat, 16 Jan 2016 13:09:37 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Tejun Heo <tj@...nel.org>, Andy Lutomirski <luto@...capital.net>
Cc:	linux-ide@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] libata: disable forced PORTS_IMPL for >= AHCI 1.3

Hello.

On 1/15/2016 11:13 PM, Tejun Heo wrote:

> Some early controllers incorrectly reported zero ports in PORTS_IMPL
> register and the ahci driver fabricates PORTS_IMPL from the number of
> ports in those cases.  This hasn't mattered but with the new nvme
> controllers there are cases where zero PORTS_IMPL is valid and should
> be honored.
>
> Disable the workaround for >= AHCI 1.3.
>
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Reported-by: Andy Lutomirski <luto@...capital.net>
> Link: http://lkml.kernel.org/g/CALCETrU7yMvXEDhjAUShoHEhDwifJGapdw--BKxsP0jmjKGmRw@mail.gmail.com
> ---
> Hello, Andy.
>
> Can you please see whether this one works?
>
> Thanks.
>
>   drivers/ata/libahci.c |    5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index d61740e..a91432a 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -496,8 +496,9 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
>   		}
>   	}
>
> -	/* fabricate port_map from cap.nr_ports */
> -	if (!port_map) {
> +	/* fabricate port_map from cap.nr_ports for < AHCI 1.3 */
> +	if (!port_map && (!(vers >> 16) ||
> +			  ((vers >> 16) == 1 && (vers & 0xFFFF) < 0x300))) {

     Hm, won't just (vers < 0x1300) just work?

MBR, Sergei