Messages in this thread | | | Date | Wed, 17 Nov 1999 10:59:33 +0300 | From | Andrey Panin <> | Subject | Re: [PATCH] ISA Plug-n-Play support for 2.3.28 |
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Theodore Y. Ts'o wrote: > > Andrey, > > Thanks for the ISA Plug-n-Play serial support. One quick question; why > the request_irq() / free_irq()? Is this to avoid the IRQ assignment > from grabbing an IRQ already used by another serial port? If so, does > this mean that the ISA Plug-n-Play boards can never share IRQ's with > another port, even if they are on the same board? > > - Ted
Hi.
Now request_irq() / free_irq() pair prevents unnecessary irq sharing (PNP resource manager assigns not irq_request()'ed IRQ's, even if these IRQ's are really used by another serial ports and free IRQ's exist).
About IRQ sharing, I'm not hardware guru and I don't now how ISA IRQ can be shared or not shared.
If IRQ sharing is possible, then next I want to implement such algorithm: - first try to get free IRQ; - if dev->prepare() / dev->activate() failed (this most probably means that here is no free IRQ), then let PNP resource manager assign IRQ and repeat device activation with shared IRQ.
Andrey
P.S. Sorry for my bad English :(
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