On 09/17/2015 11:13 PM, Russell King - ARM Linux wrote: > On Thu, Sep 17, 2015 at 12:57:53PM +0200, Daniel Lezcano wrote: >> Hi Thomas, >> >> there is one thing I don't understand. >> >> If the IRQ0 is invalid, irq_of_parse_and_map returning zero means an error >> and from what you said it is ok. >> >> But I see the NO_IRQ on ARM is (-1) and the drivers are checking with NO_IRQ >> the return code of irq_of_parse_and_map. So if there is an error, that won't >> be detected. Hi Russel, > NO_IRQ being -1 is a legacy thing for ARM - all ARM drivers are supposed > to be converted to use <= 0 or == 0 to detect invalid IRQs, and _eventually_ > once all users are gone, NO_IRQ deleted. > > Moreover, there are supposed to be no _new_ users of NO_IRQ ever added to > the kernel. > > Modern drivers should _all_ be using !irq to detect invalid IRQs, and not > using NO_IRQ. Ah, ok. Thanks for the clarification. > The steps here are: > > 1. Convert all ARM platforms to start numbering IRQs from 1 rather than 0. > 2. Convert all drivers used on ARM to detect lack of IRQ by checking for > <= 0. > 3. Replace NO_IRQ assignments with zero-initialisations. > 4. Remove NO_IRQ. > > The reason it hasn't happened is that it requires effort and testing, > and rather than running around getting old platforms to boot (which > includes remembering _how_ to get them to boot) with recent kernels, > I prefer to spend my time doing more productive work with modern code. I understand. I will take the opportunity track down those NO_IRQ in the clocksource directory. -- Daniel -- <http://www.linaro.org/> Linaro.org ? Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
