Re: [PATCH v3 04/23] dt-bindings: ata: sata: Extend number of SATA ports

[Hannes Reinecke <hare@suse.de>]

On 5/12/22 01:17, Serge Semin wrote:
> The denoted in the description upper limit only concerns the Port
> Multipliers, but not the actual SATA ports. It's an external device
> attached to a SATA port in order to access more than one SATA-drive. So
> when it's attached to a SATA port it just extends the port capability
> while the number of actual SATA ports stays the same. For instance on AHCI
> controllers the number of actual ports is determined by the CAP.NP field
> and the PI (Ports Implemented) register. AFAICS in general the maximum
> number of SATA ports depends on the particular controller implementation.
> Generic AHCI controller can't have more than 32 ports (since CAP.NP is of
> 5 bits wide and PI register is 32-bits size), while DWC AHCI SATA
> controller can't be configured with more than 8 ports activated. So let's
> discard the SATA ports reg-property restrictions and just make sure that
> it consists of a single reg-item.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> ---
> 
> Changelog v2:
> - Add comma and replace "channel" with "SATA port" in the reg property
>    description (@Damien).
> ---
>   Documentation/devicetree/bindings/ata/sata-common.yaml | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/ata/sata-common.yaml b/Documentation/devicetree/bindings/ata/sata-common.yaml
> index 7ac77b1c5850..9c9c621761ca 100644
> --- a/Documentation/devicetree/bindings/ata/sata-common.yaml
> +++ b/Documentation/devicetree/bindings/ata/sata-common.yaml
> @@ -41,11 +41,10 @@ patternProperties:
>       properties:
>         reg:
>           minimum: 0
> -        maximum: 14
>           description:
> -          The ID number of the drive port SATA can potentially use a port
> -          multiplier making it possible to connect up to 15 disks to a single
> -          SATA port.
> +          The ID number of the SATA port. Aside with being directly used,
> +          each port can have a Port Multiplier attached thus allowing to
> +          access more than one drive by means of a single SATA port.
>   
>   additionalProperties: true
>   
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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