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

Rob Herring
2022-05-17T19:15:50Z

On Thu, 12 May 2022 02:17:51 +0300, 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(-)
>

Reviewed-by: Rob Herring <robh@kernel.org>