Messages in this thread | | | Date | Fri, 11 May 2018 15:28:58 +1000 (AEST) | From | Finn Thain <> | Subject | Re: [PATCH net] macmace: Set platform device coherent_dma_mask |
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On Fri, 11 May 2018, Michael Schmitz wrote:
> > I'm afraid using platform_device_register() (which you already use for > the SCC devices) is the only option handling this on a per-device basis > without touching platform core code, while at the same time keeping the > DMA mask setup out of device drivers
I don't think that will fly. If you call platform_device_register() and follow that with a dma mask assignment, you could race with the bus matching and driver probe, and we are back to the same WARNING message.
If you want to use platform_device_register(), you'd have to implement arch_setup_pdev_archdata() and use that to set up the dma mask.
> (I can see Geert's point there - device driver code might be shared > across implementations of the device on platforms with different DMA > mask requirements,, something the driver can't be expected to know > about).
As I said, these drivers might be expected to be portable between Macs and early PowerMacs, but the same dma mask would apply AFAIK.
If a platform driver isn't expected to be portable, I think either method is reasonable: arch_setup_pdev_archdata() or the method in the patch.
Anyway, there is this in arch/powerpc/kernel/setup-common.c:
void arch_setup_pdev_archdata(struct platform_device *pdev) { pdev->archdata.dma_mask = DMA_BIT_MASK(32); pdev->dev.dma_mask = &pdev->archdata.dma_mask; ...
I'm inclined to propose something similar for m68k. That should fix the problem, since arch_setup_pdev_archdata() is already in the call chain:
platform_device_register_simple() platform_device_register_resndata() platform_device_register_full() platform_device_alloc() arch_setup_pdev_archdata()
Thoughts? Will this have nasty side effects for m68k platforms that use smaller dma masks?
--
> > Cheers, > > Michael >
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