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Subject: Re: [PATCH v18 10/11] PCI/DPC: Add Error Disconnect Recover (EDR)
 support
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        ashok.raj@intel.com, Len Brown <lenb@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
References: <20200324213710.GA48671@google.com>
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Message-ID: <f71c989b-b8f8-3437-b086-a97c2aa1e2c5@linux.intel.com>
Date:   Tue, 24 Mar 2020 18:00:31 -0700
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Hi Bjorn,

On 3/24/20 2:37 PM, Bjorn Helgaas wrote:
> This is really ugly.  What's the story on this firmware?  It sounds
> defective to me.
I think there is no defined standard for this. I have checked few
_DSM implementations. Some of them return default value and some
don't. But atleast in the test hardware I use, we need this check.

> 
> Or is everybody that uses _DSM supposed to check before evaluating it?
I think its safer to do this check.
> E.g.,
> 
>    if (!acpi_check_dsm(...))
>      return -EINVAL;
> 
>    obj = acpi_evaluate_dsm(...);
> 
> If everybody is supposed to do this, it seems like the check part
> should be moved into acpi_evaluate_dsm().