Messages in this thread | | | Date | Tue, 18 Nov 2014 21:43:41 +0800 | From | Jiang Liu <> | Subject | Re: [patch 08/16] genirq: Introduce callback irq_chip.irq_write_msi_msg |
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On 2014/11/18 21:33, Yun Wu (Abel) wrote: > On 2014/11/18 18:19, Thomas Gleixner wrote: > >> On Tue, 18 Nov 2014, Yun Wu (Abel) wrote: >>> On 2014/11/12 21:43, Thomas Gleixner wrote: >>>> struct irq_chip { >>>> @@ -359,6 +360,7 @@ struct irq_chip { >>>> void (*irq_release_resources)(struct irq_data *data); >>>> >>>> void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg); >>>> + void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg); >>> >>> Hmm... It's really weird. >>> I don't think it's the interrupt controllers' responsibility to write messages >>> for all the endpoint devices since the methods of configuring message registers >>> may different between these devices. And theoretically, the endpoint devices >>> themselves should take the responsibility to configure their message registers. >>> To say the least, the write_msg callback here still need to call some certain >>> interfaces provided by the corresponding device. >>> >>> There would be lots of ARM new devices capable of sending message >>> based interrupts to interrupt controllers, does all the drivers of >>> the devices need to expose a write_msg callback to interrupt >>> controllers? >> >> Well, writing the message _IS_ part of the interrupt controller. >> >> So in order to enable non PCI based MSI we want to have generic >> infrastructure with minimal per device/device class callbacks and of >> course you need to provide that callback for your special device. >> >> We already have non PCI based MSI controllers in x86 today and we need >> to handle the whole stuff with tons of copied coded extra for each of >> those. So consolidating it into common infrastructure allows us to get >> rid of the pointless copied code and reduce the per device effort to >> the relevant hardware specific callbacks. irq_write_msi_msg being one >> of those. >> > > At least, we have the same goal. > I will illustrate my thoughts by an example. > The current code is something like: > > Device A > ======== > void A_write_msg() { ... } > > Group B > (a group of devices behave same on writing messages, i.e. PCI) > ======= > void B_write_msg() { ... } > > Controller > ========== > irq_chip.irq_write_msi_msg () { > if (A) > A_write_msg(); > if (B) > B_write_msg(); > } > > It's horrible when new devices come out, since we need to modify the > controller part for each new device. > What I suggested is: > > MSI Core > ======== > struct msi_ops { .write_msg, }; > struct msi_desc { .msi_ops, }; > > write_msg() { > X = get_dev(); > irq_chip.compose_msg(X); // IRQ chips' responsibility > X_msi_ops.write_msg(); // nothing to do with IRQ chips > } > > Device A > ======== > void A_write_msg() { ... } > A_msi_ops.write_msg = A_write_msg; > > Group B > ======= > void B_write_msg() { ... } > B_msi_ops.write_msg = B_write_msg; > > Please correct me if I misunderstood anything. Hi Yun, We provide an irq_chip for each type of interrupt controller instead of devices. For the example mentioned above, if device A and Group B has different interrupt controllers, we just need to implement irq_chip_A and irq_chip_B and set irq_chip.irq_write_msi_msg() to suitable callbacks. The framework already achieves what you you want:) Regards! Gerry > > Thanks, > Abel >
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