* Re: + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree [not found] ` <20091209074533.GB8136-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> @ 2009-12-09 15:08 ` Grant Likely [not found] ` <fa686aa40912090708g45879802l6cea7b401b1434e3-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 0 siblings, 1 reply; 5+ messages in thread From: Grant Likely @ 2009-12-09 15:08 UTC (permalink / raw) To: Uwe Kleine-König Cc: dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f, mm-commits-u79uwXL29TY76Z2rM5mHXA, daniel-rDUAYElUppE, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b (resend because I forgot to cc the mailing list) 2009/12/9 Uwe Kleine-König <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>: > Hello Grant, > > On Tue, Dec 08, 2009 at 05:38:57PM -0700, Grant Likely wrote: >> > diff -puN drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing drivers/spi/spi_imx.c >> > --- a/drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing >> > +++ a/drivers/spi/spi_imx.c >> > @@ -554,7 +554,7 @@ static int __init spi_imx_probe(struct p >> > } >> > >> > spi_imx->irq = platform_get_irq(pdev, 0); >> > - if (!spi_imx->irq) { >> > + if (spi_imx->irq < 0) { >> >> This changes the old behaviour. Is that what you intended? '<= 0' perhaps? > Yes, the old check was wrong. What if the irq to use is 0? I thought > the commit log to be understandable. platform_get_irq returns -ENXIO on > error and an irq number on success. So 0 has to be interpreted as valid > irq, not an error. 0 is not a valid IRQ g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev ^ permalink raw reply [flat|nested] 5+ messages in thread
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* Re: + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree [not found] ` <fa686aa40912090708g45879802l6cea7b401b1434e3-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> @ 2009-12-09 15:32 ` Uwe Kleine-König [not found] ` <20091209153241.GB1389-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2009-12-09 17:55 ` Uwe Kleine-König 0 siblings, 2 replies; 5+ messages in thread From: Uwe Kleine-König @ 2009-12-09 15:32 UTC (permalink / raw) To: Grant Likely Cc: dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f, mm-commits-u79uwXL29TY76Z2rM5mHXA, daniel-rDUAYElUppE, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b On Wed, Dec 09, 2009 at 08:08:19AM -0700, Grant Likely wrote: > (resend because I forgot to cc the mailing list) > > 2009/12/9 Uwe Kleine-König <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>: > > Hello Grant, > > > > On Tue, Dec 08, 2009 at 05:38:57PM -0700, Grant Likely wrote: > >> > diff -puN drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing drivers/spi/spi_imx.c > >> > --- a/drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing > >> > +++ a/drivers/spi/spi_imx.c > >> > @@ -554,7 +554,7 @@ static int __init spi_imx_probe(struct p > >> > } > >> > > >> > spi_imx->irq = platform_get_irq(pdev, 0); > >> > - if (!spi_imx->irq) { > >> > + if (spi_imx->irq < 0) { > >> > >> This changes the old behaviour. Is that what you intended? '<= 0' perhaps? > > Yes, the old check was wrong. What if the irq to use is 0? I thought > > the commit log to be understandable. platform_get_irq returns -ENXIO on > > error and an irq number on success. So 0 has to be interpreted as valid > > irq, not an error. > > 0 is not a valid IRQ Hmm, on my x86 I have: $ grep '\<0:' /proc/interrupts 0: 24330 IO-APIC-edge timer arm/davinci starts at 0, too. As does arm/ns9xxx. arm/pxa seems to start at 1. realview starts at 1, too. So four out of five make are wrong? Seems like a big area for cleanup. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev ^ permalink raw reply [flat|nested] 5+ messages in thread
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* Re: + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree [not found] ` <20091209153241.GB1389-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> @ 2009-12-09 17:23 ` Grant Likely 0 siblings, 0 replies; 5+ messages in thread From: Grant Likely @ 2009-12-09 17:23 UTC (permalink / raw) To: Uwe Kleine-König Cc: dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f, mm-commits-u79uwXL29TY76Z2rM5mHXA, Greg Kroah-Hartman, daniel-rDUAYElUppE, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b, David Vrabel 2009/12/9 Uwe Kleine-König <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>: > On Wed, Dec 09, 2009 at 08:08:19AM -0700, Grant Likely wrote: >> >> This changes the old behaviour. Is that what you intended? '<= 0' perhaps? >> > Yes, the old check was wrong. What if the irq to use is 0? I thought >> > the commit log to be understandable. platform_get_irq returns -ENXIO on >> > error and an irq number on success. So 0 has to be interpreted as valid >> > irq, not an error. >> >> 0 is not a valid IRQ > Hmm, on my x86 I have: > > $ grep '\<0:' /proc/interrupts > 0: 24330 IO-APIC-edge timer > > arm/davinci starts at 0, too. As does arm/ns9xxx. arm/pxa seems to > start at 1. realview starts at 1, too. So four out of five make are > wrong? Seems like a big area for cleanup. As discussed on IRC, regardless of some of the core & arch use cases. As far as drivers are concerned, 0 is not a valid IRQ. Linus' comments here were referenced: http://lkml.org/lkml/2005/11/21/221 The return of -ENXIO was added in commit 305b3228, and it is definitely in the workaround category. Damn. And a quick grep show a lot of broken drivers because of it. (variations on the common 'if (!irq)' pattern abound as well as a large number of the variant 'if (irq < 0)'). Well. Though I don't like it, I will take the patch as testing for <= 0 instead of < 0. At least that doesn't create new situations of 0 being used as a valid IRQ. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree 2009-12-09 15:32 ` Uwe Kleine-König [not found] ` <20091209153241.GB1389-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> @ 2009-12-09 17:55 ` Uwe Kleine-König 2009-12-09 18:00 ` Grant Likely 1 sibling, 1 reply; 5+ messages in thread From: Uwe Kleine-König @ 2009-12-09 17:55 UTC (permalink / raw) To: Grant Likely Cc: akpm, mm-commits, daniel, dbrownell, s.hauer, spi-devel-general, linux-kernel On Wed, Dec 09, 2009 at 04:32:41PM +0100, Uwe Kleine-König wrote: > On Wed, Dec 09, 2009 at 08:08:19AM -0700, Grant Likely wrote: > > (resend because I forgot to cc the mailing list) > > > > 2009/12/9 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>: > > > Hello Grant, > > > > > > On Tue, Dec 08, 2009 at 05:38:57PM -0700, Grant Likely wrote: > > >> > diff -puN drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing drivers/spi/spi_imx.c > > >> > --- a/drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing > > >> > +++ a/drivers/spi/spi_imx.c > > >> > @@ -554,7 +554,7 @@ static int __init spi_imx_probe(struct p > > >> > } > > >> > > > >> > spi_imx->irq = platform_get_irq(pdev, 0); > > >> > - if (!spi_imx->irq) { > > >> > + if (spi_imx->irq < 0) { > > >> > > >> This changes the old behaviour. Is that what you intended? '<= 0' perhaps? > > > Yes, the old check was wrong. What if the irq to use is 0? I thought > > > the commit log to be understandable. platform_get_irq returns -ENXIO on > > > error and an irq number on success. So 0 has to be interpreted as valid > > > irq, not an error. > > > > 0 is not a valid IRQ > Hmm, on my x86 I have: > > $ grep '\<0:' /proc/interrupts > 0: 24330 IO-APIC-edge timer > > arm/davinci starts at 0, too. As does arm/ns9xxx. arm/pxa seems to > start at 1. realview starts at 1, too. So four out of five make are > wrong? Seems like a big area for cleanup. I've read a bit and I think the best for a driver writer (i.e. the role I have when changing drivers/spi/spi_imx.c) is to accept what platform_get_irq returns to me. If the platform specified struct resource mydevicesresources[] = { ... { .start = 0, .end = 0, .flags = IORESOURCE_IRQ, }, ... }; then the best thing to do is to take irq0, isn't it. So as platform_get_irq is implemented as int platform_get_irq(struct platform_device *dev, unsigned int num) { struct resource *r = platform_get_resource(dev, IORESOURCE_IRQ, num); return r ? r->start : -ENXIO; } testing for <0 seems right to me. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree 2009-12-09 17:55 ` Uwe Kleine-König @ 2009-12-09 18:00 ` Grant Likely 0 siblings, 0 replies; 5+ messages in thread From: Grant Likely @ 2009-12-09 18:00 UTC (permalink / raw) To: Uwe Kleine-König Cc: akpm, mm-commits, daniel, dbrownell, s.hauer, spi-devel-general, linux-kernel 2009/12/9 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>: > On Wed, Dec 09, 2009 at 04:32:41PM +0100, Uwe Kleine-König wrote: >> On Wed, Dec 09, 2009 at 08:08:19AM -0700, Grant Likely wrote: >> > (resend because I forgot to cc the mailing list) >> > >> > 2009/12/9 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>: >> > > Hello Grant, >> > > >> > > On Tue, Dec 08, 2009 at 05:38:57PM -0700, Grant Likely wrote: >> > >> > diff -puN drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing drivers/spi/spi_imx.c >> > >> > --- a/drivers/spi/spi_imx.c~spi-imx-correct-check-for-platform_get_irq-failing >> > >> > +++ a/drivers/spi/spi_imx.c >> > >> > @@ -554,7 +554,7 @@ static int __init spi_imx_probe(struct p >> > >> > } >> > >> > >> > >> > spi_imx->irq = platform_get_irq(pdev, 0); >> > >> > - if (!spi_imx->irq) { >> > >> > + if (spi_imx->irq < 0) { >> > >> >> > >> This changes the old behaviour. Is that what you intended? '<= 0' perhaps? >> > > Yes, the old check was wrong. What if the irq to use is 0? I thought >> > > the commit log to be understandable. platform_get_irq returns -ENXIO on >> > > error and an irq number on success. So 0 has to be interpreted as valid >> > > irq, not an error. >> > >> > 0 is not a valid IRQ >> Hmm, on my x86 I have: >> >> $ grep '\<0:' /proc/interrupts >> 0: 24330 IO-APIC-edge timer >> >> arm/davinci starts at 0, too. As does arm/ns9xxx. arm/pxa seems to >> start at 1. realview starts at 1, too. So four out of five make are >> wrong? Seems like a big area for cleanup. > I've read a bit and I think the best for a driver writer (i.e. the role > I have when changing drivers/spi/spi_imx.c) is to accept what > platform_get_irq returns to me. If the platform specified > > struct resource mydevicesresources[] = { > ... > { > .start = 0, > .end = 0, > .flags = IORESOURCE_IRQ, > }, > ... > }; > > then the best thing to do is to take irq0, isn't it. So as > platform_get_irq is implemented as > > int platform_get_irq(struct platform_device *dev, unsigned int num) > { > struct resource *r = platform_get_resource(dev, IORESOURCE_IRQ, num); > > return r ? r->start : -ENXIO; > } > > testing for <0 seems right to me. Regardless. I won't accept that change for a theoretical use case. In the general case I'll maintain the pattern that irq 0 is invalid unless it is the only way to get around a real problem. g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2009-12-09 18:00 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <200912082330.nB8NU4IO016215@imap1.linux-foundation.org> [not found] ` <fa686aa40912081638m734e97c3r2c3f412898d293b@mail.gmail.com> [not found] ` <20091209074533.GB8136@pengutronix.de> [not found] ` <20091209074533.GB8136-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2009-12-09 15:08 ` + spi-imx-correct-check-for-platform_get_irq-failing.patch added to -mm tree Grant Likely [not found] ` <fa686aa40912090708g45879802l6cea7b401b1434e3-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2009-12-09 15:32 ` Uwe Kleine-König [not found] ` <20091209153241.GB1389-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> 2009-12-09 17:23 ` Grant Likely 2009-12-09 17:55 ` Uwe Kleine-König 2009-12-09 18:00 ` Grant Likely
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