Hi Finn,
Am 11.05.2018 um 22:06 schrieb Finn Thain:
You would have to be careful not to overwrite a pdev->dev.dma_mask and
pdev->dev.dma_coherent_mask that might have been set in a platform
device passed via platform_device_register here. Coldfire is the only
m68k platform currently using that, but there might be others in future.
That Coldfire patch could be reverted if this is a better solution.
True, but there might be other uses for deviating from a platform
default (I'm thinking of Atari SCSI and floppy drivers here). But we
could chose the correct mask to set in arch_setup_pdev_archdata()
instead, as it's a platform property not a driver property in that case.
... But I don't think there are smaller DMA masks used by m68k drivers
that use the platform device mechanism at present. I've only looked at
arch/m68k though.
So we're back at the same problem that Geert's suggestion also raised: how
to identify potentially affected platform devices and drivers?
Maybe we can take a leaf out of Christoph's book, and leave a noisy
WARNING splat in the log.
void arch_setup_pdev_archdata(struct platform_device *pdev)
{
WARN_ON_ONCE(pdev->dev.coherent_dma_mask != DMA_MASK_NONE ||
pdev->dev.dma_mask != NULL);
I'd suggest using WARN_ON() so we catch all uses on a particular platform.
I initially thought it necessary to warn on unset mask here, but I see
that would throw up a lot of redundant false positives.
Cheers,
Michael
--
To unsubscribe from this list: send the line "unsubscribe linux-m68k" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
