Messages in this thread | | | Subject | Re: [PATCH v2] bus: hisi_lpc: Don't use devm_kzalloc() to allocate logical PIO range | From | John Garry <> | Date | Tue, 18 Jun 2019 09:44:26 +0100 |
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>>
- zhichang personal mail
>> It's now on my todo list. >> >> I'll need advice on how to test this for hot-pluggable host bridges. >> >>> >>> Could you just move the logic_pio_register_range() call farther down >>> in hisi_lpc_probe()? IIUC, once logic_pio_register_range() returns, >>> an inb() with the right port number will try to access that port, so >>> we should be prepared for that, i.e., maybe this in the wrong order to >>> begin with? >> >> No, unfortunately we can't. The reason is that we need the logical PIO >> base for that range before we enumerate the children of that host. We >> need that base address for "translating" the child bus addresses to >> logical PIO addresses. >
Hi Bjorn,
> Ah, yeah, that makes sense. I think. We do assume that we know all > the MMIO and I/O port translations before enumerating devices. It's > *conceivable* that could be changed someday since we don't actually > need the translations until a driver claims the device,
We actually need them before a driver claims the device.
The reason is that when we create that child platform device we set the device's IORESOURCE_IO resources according to the translated logic PIO addresses, and not the host bus address. This is what makes the host transparent to the child device driver.
and it would > gain some flexibility if we didn't have to program the host bridge > windows until we know how much space is required. But I don't see > that happening anytime soon. > > Bjorn > > . >
BTW, as you may have noticed, in v3 I said I would drop this patch and fix it all properly.
My problem is that I need to ensure that the new logical PIO unregister function works ok for hot-pluggable host bridges. I need to get some way to test this. Advice?
Thanks, John
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