From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Jean Delvare <jdelvare@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-acpi@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 2/4] x86/pci: Re-use new dmi_get_bios_year() helper
Date: Wed, 28 Feb 2018 12:29:04 +0200 [thread overview]
Message-ID: <1519813744.10722.258.camel@linux.intel.com> (raw)
In-Reply-To: <20180226172832.7bf82336@endymion>
On Mon, 2018-02-26 at 17:28 +0100, Jean Delvare wrote:
> > - if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year
> > < 2008) {
> > - if (iomem_resource.end <= 0xffffffff)
> > - pci_use_crs = false;
> > - }
> > + if ((dmi_get_bios_year() < 2008) && (iomem_resource.end <=
> > 0xffffffff))
> > + pci_use_crs = false;
>
> You are changing the behavior here, when DMI does not provide a BIOS
> date. Beforehand, the test would fail and pci_use_crs would be left
> alone. After your change, dmi_get_bios_year() will return 0, and
> "0 < 2008" is true, so pci_use_crs is set to false.
Hmm... Indeed.
> I have no opinion on what this driver should do in such case,
I would assume that no BIOS date is related to prehistoric firmwares and
using _CRS would sound weird on them.
> but I
> certainly wouldn't expect a change of behavior from a "use a helper
> instead of open-coding" kind of patch.
Agree.
> I don't think you can safely assume that the code calling
> dmi_get_bios_year() will always do the right thing when 0 is being
> returned. It's up to the calling code to decide what the default
> behavior should be.
That's correct.
--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
next prev parent reply other threads:[~2018-02-28 10:29 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 12:59 [PATCH v1 1/4] dmi: Introduce dmi_get_bios_year() helper Andy Shevchenko
2018-02-22 12:59 ` [PATCH v1 2/4] x86/pci: Re-use new " Andy Shevchenko
2018-02-23 8:25 ` [tip:x86/platform] x86/pci: Simplify code by using the " tip-bot for Andy Shevchenko
2018-02-23 21:39 ` [PATCH v1 2/4] x86/pci: Re-use " Bjorn Helgaas
2018-02-26 16:28 ` Jean Delvare
2018-02-28 10:29 ` Andy Shevchenko [this message]
2018-02-28 10:33 ` Rafael J. Wysocki
2018-02-28 19:21 ` Jean Delvare
2018-02-28 19:34 ` Andy Shevchenko
2018-02-22 12:59 ` [PATCH v1 3/4] ACPI / sleep: " Andy Shevchenko
2018-02-23 8:25 ` [tip:x86/platform] ACPI/sleep: Simplify code by using the " tip-bot for Andy Shevchenko
2018-02-26 16:31 ` [PATCH v1 3/4] ACPI / sleep: Re-use " Jean Delvare
2018-02-22 12:59 ` [PATCH v1 4/4] pci: " Andy Shevchenko
2018-02-23 8:26 ` [tip:x86/platform] pci: Simplify code by using the " tip-bot for Andy Shevchenko
2018-02-23 21:40 ` [PATCH v1 4/4] pci: Re-use " Bjorn Helgaas
2018-02-25 13:27 ` Andy Shevchenko
2018-02-26 18:19 ` Bjorn Helgaas
2018-02-28 10:12 ` Andy Shevchenko
2018-02-28 15:17 ` Bjorn Helgaas
2018-02-26 20:40 ` Jean Delvare
2018-02-23 8:24 ` [tip:x86/platform] dmi: Introduce the dmi_get_bios_year() helper function tip-bot for Andy Shevchenko
2018-02-23 21:35 ` [PATCH v1 1/4] dmi: Introduce dmi_get_bios_year() helper Bjorn Helgaas
2018-02-25 13:23 ` Andy Shevchenko
2018-02-26 9:29 ` Rafael J. Wysocki
2018-02-28 10:14 ` Andy Shevchenko
2018-02-27 9:14 ` Jean Delvare
2018-02-28 10:33 ` Andy Shevchenko
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