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From: Bjorn Helgaas <helgaas@kernel.org>
To: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>
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>
Subject: Re: [PATCH v18 10/11] PCI/DPC: Add Error Disconnect Recover (EDR) support
Date: Thu, 26 Mar 2020 17:36:37 -0500
Message-ID: <20200326223637.GA106135@google.com> (raw)
In-Reply-To: <f71c989b-b8f8-3437-b086-a97c2aa1e2c5@linux.intel.com>

On Tue, Mar 24, 2020 at 06:00:31PM -0700, Kuppuswamy, Sathyanarayanan wrote:
> 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.

I agree that I don't see anything in the ACPI spec v6.3 about what
should happen if we supply a Function Index that isn't supported.
That looks like a hole in the spec.

> > 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().

So my question, and I guess this is really for Rafael, is that since
it seems like *everybody* needs to use acpi_check_dsm() in order to
use acpi_evaluate_dsm() safely, why don't we move the check *into*
acpi_evaluate_dsm()?

It's just error prone if we expect everybody to call both interfaces.

Bjorn

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24  0:25 [PATCH v18 00/11] " sathyanarayanan.kuppuswamy
2020-03-24  0:25 ` [PATCH v18 01/11] PCI/ERR: Update error status after reset_link() sathyanarayanan.kuppuswamy
2020-03-24  0:25 ` [PATCH v18 02/11] PCI: move {pciehp,shpchp}_is_native() definitions to pci.c sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 03/11] PCI/DPC: Fix DPC recovery issue in non hotplug case sathyanarayanan.kuppuswamy
2020-03-24 23:49   ` Bjorn Helgaas
2020-03-25  1:17     ` Kuppuswamy, Sathyanarayanan
2020-03-28 17:10       ` Bjorn Helgaas
2020-03-28 22:04         ` Kuppuswamy, Sathyanarayanan
2020-03-28 22:21           ` Bjorn Helgaas
2020-03-28 22:40             ` Kuppuswamy, Sathyanarayanan
2020-03-24  0:26 ` [PATCH v18 04/11] PCI/DPC: Move DPC data into struct pci_dev sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 05/11] PCI/ERR: Remove service dependency in pcie_do_recovery() sathyanarayanan.kuppuswamy
2020-03-28 21:12   ` Kuppuswamy, Sathyanarayanan
2020-03-28 21:32     ` Bjorn Helgaas
2020-03-28 21:55       ` Kuppuswamy, Sathyanarayanan
2020-03-28 22:16         ` Bjorn Helgaas
2020-03-24  0:26 ` [PATCH v18 06/11] PCI/ERR: Return status of pcie_do_recovery() sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 07/11] PCI/DPC: Cache DPC capabilities in pci_init_capabilities() sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 08/11] PCI/AER: Add pci_aer_raw_clear_status() to unconditionally clear Error Status sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 09/11] PCI/DPC: Expose dpc_process_error(), dpc_reset_link() for use by EDR sathyanarayanan.kuppuswamy
2020-03-24  0:26 ` [PATCH v18 10/11] PCI/DPC: Add Error Disconnect Recover (EDR) support sathyanarayanan.kuppuswamy
2020-03-24 21:37   ` Bjorn Helgaas
2020-03-25  1:00     ` Kuppuswamy, Sathyanarayanan
2020-03-26 22:36       ` Bjorn Helgaas [this message]
2020-03-24  0:26 ` [PATCH v18 11/11] PCI/AER: Rationalize error status register clearing sathyanarayanan.kuppuswamy
2020-03-31 15:28 ` [PATCH v18 00/11] Add Error Disconnect Recover (EDR) support Bjorn Helgaas
2020-03-31 16:28   ` Kuppuswamy, Sathyanarayanan

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