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Message-ID: <4891976.lTa9ZQzyVA@vostro.rjw.lan>
Date: Fri, 24 Jan 2014 18:19:55 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Yijing Wang <wangyijing@...wei.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Jani Nikula <jani.nikula@...ux.intel.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
David Airlie <airlied@...ux.ie>,
intel-gfx@...ts.freedesktop.org,
DRI mailing list <dri-devel@...ts.freedesktop.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
Dave Airlie <airlied@...hat.com>,
Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH v5] ACPI: Fix acpi_evaluate_object() return value check
On Friday, January 24, 2014 08:25:23 AM Bjorn Helgaas wrote:
> On Fri, Jan 24, 2014 at 8:36 AM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> > On Friday, January 24, 2014 07:54:29 AM Bjorn Helgaas wrote:
> >> On Thu, Jan 23, 2014 at 5:33 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> >> > On Thursday, January 23, 2014 11:21:01 AM Bjorn Helgaas wrote:
> >> >> On Wed, Jan 22, 2014 at 8:42 PM, Yijing Wang <wangyijing@...wei.com> wrote:
> >> >> > Since acpi_evaluate_object() returns acpi_status and not plain int,
> >> >> > ACPI_FAILURE() should be used for checking its return value. Also
> >> >> > add some detailed debug info when acpi_evaluate_object() failed.
> >> >> >
> >> >> > Reviewed-by: Jani Nikula <jani.nikula@...el.com>
> >> >> > Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> >> >> > Signed-off-by: Yijing Wang <wangyijing@...wei.com>
> >> >> > ---
> >> >> > v4->v5: Add some detailed debug info for acpi_evaluate_object()
> >> >> > failure suggested by Bjorn.
> >> >> > v3->v4: Fix spell error, add Jani Nikula reviewed-by.
> >> >> > v2->v3: Fix compile error pointed out by Hanjun.
> >> >> > v1->v2: Add CC to related subsystem MAINTAINERS
> >> >> > ---
> >> >> > drivers/gpu/drm/i915/intel_acpi.c | 33 ++++++++++++++++-------
> >> >> > drivers/gpu/drm/nouveau/core/subdev/mxm/base.c | 13 ++++++---
> >> >> > drivers/gpu/drm/nouveau/nouveau_acpi.c | 25 +++++++++++-------
> >> >> > drivers/pci/pci-label.c | 10 +++++--
> >> >> > 4 files changed, 54 insertions(+), 27 deletions(-)
> >> >> >
> >> >> > diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > index dfff090..e7b526b 100644
> >> >> > --- a/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > +++ b/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > @@ -31,11 +31,13 @@ static const u8 intel_dsm_guid[] = {
> >> >> > static int intel_dsm(acpi_handle handle, int func)
> >> >> > {
> >> >> > struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
> >> >> > + struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
> >> >> > struct acpi_object_list input;
> >> >> > union acpi_object params[4];
> >> >> > union acpi_object *obj;
> >> >> > u32 result;
> >> >> > - int ret = 0;
> >> >> > + acpi_status status;
> >> >> > + int ret;
> >> >> >
> >> >> > input.count = 4;
> >> >> > input.pointer = params;
> >> >> > @@ -50,10 +52,14 @@ static int intel_dsm(acpi_handle handle, int func)
> >> >> > params[3].package.count = 0;
> >> >> > params[3].package.elements = NULL;
> >> >> >
> >> >> > - ret = acpi_evaluate_object(handle, "_DSM", &input, &output);
> >> >> > - if (ret) {
> >> >> > - DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
> >> >> > - return ret;
> >> >> > + status = acpi_evaluate_object(handle, "_DSM", &input, &output);
> >> >> > + if (ACPI_FAILURE(status)) {
> >> >> > + acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
> >> >> > + DRM_DEBUG_DRIVER(
> >> >> > + "failed to evaluate _DSM for %s, exit status %u\n",
> >> >> > + (char *)string.pointer, (unsigned int)status);
> >> >> > + kfree(string.pointer);
> >> >> > + return -EINVAL;
> >> >>
> >> >> I said "too bad there isn't an *easy* way" to include more
> >> >> information. IMHO this is too ugly and error-prone to use
> >> >> consistently. And if you are going to add more information, why did
> >> >> you only do it for some of the calls and not others?
> >> >>
> >> >> I considered adding a %p extension to print the pathname; I don't know
> >> >> if that's worthwhile or not. I think it would be ideal if we had a
> >> >> struct device and could use dev_info(), and then a way to connect the
> >> >> struct device with an ACPI path, like maybe a dmesg note when we
> >> >> create the struct device corresponding to an ACPI Device node.
> >> >
> >> > Well, we can generally print something like that from pci_acpi_setup().
> >> >
> >> > What about the below? Wouldn't it generate too much output on some systems?
> >>
> >> Yeah, that probably would generate an awful lot of output. I was just
> >> hoping to avoid treating ACPI pathnames as first-class objects. What
> >> do you think about a %p extension? I played with that once, but I
> >> seem to have lost the patch.
> >
> > Well, it may be worth doing. However, that information is readily available from
> > sysfs anyway, you only need to follow the firmware_node link in the PCI device's
> > sysfs directory and read the path attribute from there. For example, on my
> > system:
> >
> > $ cat /sys/devices/pci0000:00/0000:00:1c.4/0000:0b:00.0/firmware_node/path
> > \_SB_.PCI0.RP05.PXSX
>
> That's perfect. If we had a struct device, we could just use
> dev_info() for these messages. But I have no idea how hard it would
> be to get at the struct device.
>From the pci_dev side that is trivial: use ACPI_COMPANION(). The other way
around is rather more difficult as browsing a list would be involved.
Rafael
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