Messages in this thread | | | Date | Wed, 06 Mar 2013 15:02:42 +0800 | From | Mike Qiu <> | Subject | Re: [PATCH 2/3] irq: Add hw continuous IRQs map to virtual continuous IRQs support |
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于 2013/3/6 13:42, Michael Ellerman 写道: > On Wed, Mar 06, 2013 at 01:34:58PM +0800, Mike Qiu wrote: >> 于 2013/3/6 11:54, Michael Ellerman 写道: >>> On Tue, Mar 05, 2013 at 03:19:57PM +0800, Mike Qiu wrote: >>>> 于 2013/3/5 10:23, Michael Ellerman 写道: >>>>> On Tue, Jan 15, 2013 at 03:38:55PM +0800, Mike Qiu wrote: >>>>>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c >>>>>> index 96f3a1d..38648e6 100644 >>>>>> --- a/kernel/irq/irqdomain.c >>>>>> +++ b/kernel/irq/irqdomain.c >>>>>> @@ -636,6 +636,67 @@ int irq_create_strict_mappings(struct irq_domain *domain, unsigned int irq_base, >>>>>> } >>>>>> EXPORT_SYMBOL_GPL(irq_create_strict_mappings); >>>>>> +/** >>>>>> + * irq_create_mapping_many - Map a range of hw IRQs to a range of virtual IRQs >>>>>> + * @domain: domain owning the interrupt range >>>>>> + * @hwirq_base: beginning of continuous hardware IRQ range >>>>>> + * @count: Number of interrupts to map >>>>> For multiple-MSI the allocated interrupt numbers must be a power-of-2, >>>>> and must be naturally aligned. I don't /think/ that's a requirement for >>>>> the virtual numbers, but it's probably best that we do it anyway. >>>>> >>>>> So this API needs to specify that it will give you back a power-of-2 >>>>> block that is naturally aligned - otherwise you can't use it for MSI. >>>> rtas_call will return the numbers of hardware interrupt, and it >>>> should be power-of-2, as this I think do not need to specify >>> You're confusing hardware interrupt numbers and virtual interrupt >>> numbers. My comment is about irq_create_mapping_many(), which returns >>> virtual interrupt numbers. >>> >>> As I said I don't think there is a requirement that the virtual >>> interrupt numbers are also a power-of-2 naturally aligned block, but we >>> should allocate them as one anyway, to avoid any issues in future. >> But for virtual interrupt numbersit should be a power-of-2 naturally >> aligned block, because it must be continuous, as the MSI-HOWTO.txt says: >> >> 4.2.2 pci_enable_msi_block >> int pci_enable_msi_block(struct pci_dev *dev, int count) >> This variation on the above call allows a device driver to request >> multiple MSIs. The MSI specification only allows interrupts to be >> allocated in powers of two, up to a maximum of 2^5 (32). >> If this function returns 0, it has succeeded in allocating at least >> as many interrupts as the driver requested >> (it may have allocated more in order to satisfy the power-of-two >> requirement). In this case, the function enables MSI on this device >> and updates dev->irq to be the lowest of the new interrupts >> assigned to it. The other interrupts assigned to the device are in >> the range dev->irq to dev->irq + count - 1. >> >> See the last line, that means for the virtual interrupts must be a >> continuous block. > In practice I think things could work if we didn't, because we are not > using the mask routines that assume that layout. > > But you're right, we must implement the API as it's specified, so the > virtual interrupt numbers must be a naturally aligned power-of-2. Yes, also your opinion is also right, just becasue the API requires a naturally aligned power-of-2 interrupt numbers, so we need to implement it like this.
cheers > > cheers >
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