| Message ID | 1508018851-9272-4-git-send-email-festevam@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
+ gkh, maz, tglx, linus w On 15/10/2017 00:07, Fabio Estevam wrote: > When platform_get_irq() fails we should propagate the real error value > instead of always returning -ENXIO. > > Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com> > Signed-off-by: Fabio Estevam <festevam@gmail.com> > --- > drivers/pci/host/pcie-tango.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c > index e23f738..5196583 100644 > --- a/drivers/pci/host/pcie-tango.c > +++ b/drivers/pci/host/pcie-tango.c > @@ -272,9 +272,9 @@ static int tango_pcie_probe(struct platform_device *pdev) > writel_relaxed(0, pcie->base + SMP8759_ENABLE + offset); > > virq = platform_get_irq(pdev, 1); > - if (virq <= 0) { > + if (virq < 0) { > dev_err(dev, "Failed to map IRQ\n"); > - return -ENXIO; > + return virq; > } > > irq_dom = irq_domain_create_linear(fwnode, MSI_MAX, &dom_ops, pcie); Hello Fabio, I don't think this patch is correct. AFAIU, on all but legacy platforms, when platform_get_irq() returns 0, it is to signal an error condition. Marc Z pointed out this discussion: http://yarchive.net/comp/linux/zero.html Looking more closely at the platform_get_irq implementation, and ignoring the CONFIG_SPARC special-case, the return value is either: * a valid virq > 0, or * -EPROBE_DEFER, or * some error code < 0, in the ACPI case, or * -ENXIO, or * res->start (an unsigned type, so >= 0) I suppose it would be slightly nicer to write: virq = platform_get_irq(pdev, 1); if (virq <= 0) return virq ? virq : -ENODEV; Regards.
On Mon, Oct 16, 2017 at 11:09 AM, Marc Gonzalez <marc_gonzalez@sigmadesigns.com> wrote: > I don't think this patch is correct. > > AFAIU, on all but legacy platforms, when platform_get_irq() returns 0, > it is to signal an error condition. > > Marc Z pointed out this discussion: > http://yarchive.net/comp/linux/zero.html Same comment as I had, more or less. > I suppose it would be slightly nicer to write: > > virq = platform_get_irq(pdev, 1); > if (virq <= 0) > return virq ? virq : -ENODEV; This looks good to me. Yours, Linus Walleij
On Mon, Oct 16, 2017 at 11:09:15AM +0200, Marc Gonzalez wrote: > + gkh, maz, tglx, linus w > > On 15/10/2017 00:07, Fabio Estevam wrote: > > > When platform_get_irq() fails we should propagate the real error value > > instead of always returning -ENXIO. > > > > Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com> > > Signed-off-by: Fabio Estevam <festevam@gmail.com> > > --- > > drivers/pci/host/pcie-tango.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c > > index e23f738..5196583 100644 > > --- a/drivers/pci/host/pcie-tango.c > > +++ b/drivers/pci/host/pcie-tango.c > > @@ -272,9 +272,9 @@ static int tango_pcie_probe(struct platform_device *pdev) > > writel_relaxed(0, pcie->base + SMP8759_ENABLE + offset); > > > > virq = platform_get_irq(pdev, 1); > > - if (virq <= 0) { > > + if (virq < 0) { > > dev_err(dev, "Failed to map IRQ\n"); > > - return -ENXIO; > > + return virq; > > } > > > > irq_dom = irq_domain_create_linear(fwnode, MSI_MAX, &dom_ops, pcie); > > Hello Fabio, > > I don't think this patch is correct. > > AFAIU, on all but legacy platforms, when platform_get_irq() returns 0, > it is to signal an error condition. > > Marc Z pointed out this discussion: > http://yarchive.net/comp/linux/zero.html > > Looking more closely at the platform_get_irq implementation, and ignoring > the CONFIG_SPARC special-case, the return value is either: > > * a valid virq > 0, or > * -EPROBE_DEFER, or > * some error code < 0, in the ACPI case, or > * -ENXIO, or > * res->start (an unsigned type, so >= 0) > > > I suppose it would be slightly nicer to write: > > virq = platform_get_irq(pdev, 1); > if (virq <= 0) > return virq ? virq : -ENODEV; All these return values end up getting returned by the driver probe() functions. I don't think there's much value in returning the exact error we got from platform_get_irq() vs a generic error like -ENXIO or -ENODEV, so my $0.02 is that the above is more complicated than it's worth. I think existing code that looks like: irq = platform_get_irq(pdev, 0); if (irq <= 0) return -ENODEV; is fine and there's no reason to change it. For code that doesn't check the platform_get_irq() return value, I'd say it's worth adding a check for "irq <= 0". Maybe somebody will point out an arch that can return 0 as a legitimate IRQ, and then we'll have to rethink. Bjorn
+ linus t, mark b On 21/10/2017 00:31, Bjorn Helgaas wrote: > On Mon, Oct 16, 2017 at 11:09:15AM +0200, Marc Gonzalez wrote: > >> + gkh, maz, tglx, linus w >> >> On 15/10/2017 00:07, Fabio Estevam wrote: >> >>> When platform_get_irq() fails we should propagate the real error value >>> instead of always returning -ENXIO. >>> >>> Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com> >>> Signed-off-by: Fabio Estevam <festevam@gmail.com> >>> --- >>> drivers/pci/host/pcie-tango.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c >>> index e23f738..5196583 100644 >>> --- a/drivers/pci/host/pcie-tango.c >>> +++ b/drivers/pci/host/pcie-tango.c >>> @@ -272,9 +272,9 @@ static int tango_pcie_probe(struct platform_device *pdev) >>> writel_relaxed(0, pcie->base + SMP8759_ENABLE + offset); >>> >>> virq = platform_get_irq(pdev, 1); >>> - if (virq <= 0) { >>> + if (virq < 0) { >>> dev_err(dev, "Failed to map IRQ\n"); >>> - return -ENXIO; >>> + return virq; >>> } >>> >>> irq_dom = irq_domain_create_linear(fwnode, MSI_MAX, &dom_ops, pcie); >> >> Hello Fabio, >> >> I don't think this patch is correct. >> >> AFAIU, on all but legacy platforms, when platform_get_irq() returns 0, >> it is to signal an error condition. >> >> Marc Z pointed out this discussion: >> http://yarchive.net/comp/linux/zero.html >> >> Looking more closely at the platform_get_irq implementation, and ignoring >> the CONFIG_SPARC special-case, the return value is either: >> >> * a valid virq > 0, or >> * -EPROBE_DEFER, or >> * some error code < 0, in the ACPI case, or >> * -ENXIO, or >> * res->start (an unsigned type, so >= 0) >> >> >> I suppose it would be slightly nicer to write: >> >> virq = platform_get_irq(pdev, 1); >> if (virq <= 0) >> return virq ? virq : -ENODEV; > > All these return values end up getting returned by the driver probe() > functions. I don't think there's much value in returning the exact > error we got from platform_get_irq() vs a generic error like -ENXIO or > -ENODEV, so my $0.02 is that the above is more complicated than it's > worth. > > I think existing code that looks like: > > irq = platform_get_irq(pdev, 0); > if (irq <= 0) > return -ENODEV; > > is fine and there's no reason to change it. For code that doesn't > check the platform_get_irq() return value, I'd say it's worth adding a > check for "irq <= 0". Maybe somebody will point out an arch that can > return 0 as a legitimate IRQ, and then we'll have to rethink. I agree with what Bjorn wrote, but there might be one exception to consider: mapping EPROBE_DEFER to something else will likely prevent the driver core from correctly handling deferred probes. References for myself: https://lwn.net/Articles/485194/ https://patchwork.kernel.org/patch/9558675/ Regards.
diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c index e23f738..5196583 100644 --- a/drivers/pci/host/pcie-tango.c +++ b/drivers/pci/host/pcie-tango.c @@ -272,9 +272,9 @@ static int tango_pcie_probe(struct platform_device *pdev) writel_relaxed(0, pcie->base + SMP8759_ENABLE + offset); virq = platform_get_irq(pdev, 1); - if (virq <= 0) { + if (virq < 0) { dev_err(dev, "Failed to map IRQ\n"); - return -ENXIO; + return virq; } irq_dom = irq_domain_create_linear(fwnode, MSI_MAX, &dom_ops, pcie);
When platform_get_irq() fails we should propagate the real error value instead of always returning -ENXIO. Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com> Signed-off-by: Fabio Estevam <festevam@gmail.com> --- drivers/pci/host/pcie-tango.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)