Re: [PATCH v3 09/23] ata: libahci_platform: Sanity check the DT child nodes number

Serge Semin
2022-05-12T14:40:32Z

On Thu, May 12, 2022 at 11:24:22AM +0300, Sergei Shtylyov wrote:
> On 5/12/22 2:17 AM, Serge Semin wrote:
>
> > Having greater than (AHCI_MAX_PORTS = 32) ports detected isn't that
>

> Having greater than AHCI_MAX_PORTS (32) ports detected?

Ok.

>
> > critical from the further AHCI-platform initialization point of view since
> > exceeding the ports upper limit will cause allocating more resources than
> > will be used afterwards. But detecting too many child DT-nodes doesn't
> > seem right since it's very unlikely to have it on an ordinary platform. In
> > accordance with the AHCI specification there can't be more than 32 ports
> > implemented at least due to having the CAP.NP field of 4 bits wide and the
>

> It's 5 bits wide, actually...

Right =)

The denoted comments will be taken into account in v4. Thanks.

-Sergey

>
> > PI register of dword size. Thus if such situation is found the DTB must
> > have been corrupted and the data read from it shouldn't be reliable. Let's
> > consider that as an erroneous situation and halt further resources
> > allocation.
> >
> > Note it's logically more correct to have the nports set only after the
> > initialization value is checked for being sane. So while at it let's make
> > sure nports is assigned with a correct value.
> >
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
>
> [...]
>
> MBR, Sergey