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Date:   Thu, 12 May 2022 17:40:21 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Sergei Shtylyov <sergei.shtylyov@gmail.com>
Cc:     Serge Semin <Sergey.Semin@baikalelectronics.ru>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Jens Axboe <axboe@kernel.dk>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
        Rob Herring <robh+dt@kernel.org>, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v3 09/23] ata: libahci_platform: Sanity check the DT
 child nodes number
Message-ID: <20220512144021.stkajc7dimgfkldv@mobilestation>
References: <20220511231810.4928-1-Sergey.Semin@baikalelectronics.ru>
 <20220511231810.4928-10-Sergey.Semin@baikalelectronics.ru>
 <42dfc76f-a9d9-8e63-874d-b7459cef326c@gmail.com>
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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