Re: [PATCH 6/6] driver core: initialize a default DMA mask for platform device

On Thu, Aug 15, 2019 at 03:38:12PM +0200, Christoph Hellwig wrote:

On Thu, Aug 15, 2019 at 03:03:25PM +0200, Greg Kroah-Hartman wrote:

quoted

quoted

--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h

@@ -24,6 +24,7 @@ struct platform_device {
 	int		id;
 	bool		id_auto;
 	struct device	dev;
+	u64		dma_mask;

Why is the dma_mask in 'struct device' which is part of this structure,
not sufficient here?  Shouldn't the "platform" be setting that up
correctly already in the "archdata" type callback?

Becaus the dma_mask in struct device is a pointer that needs to point
to something, and this is the best space we can allocate for 'something'.
m68k and powerpc currently do something roughly equivalent at the moment,
while everyone else just has horrible, horrible hacks.  As mentioned in
the changelog the intent of this patch is that we treat platform devices
like any other bus, where the bus allocates the space for the dma_mask.
The long term plan is to eventually kill that weird pointer indirection
that doesn't help anyone, but for that we need to sort out the basics
first.

Ah, missed that, sorry.  Ok, no objection from me.  Might as well respin
this series and I can queue it up after 5.3-rc5 is out (which will have
your first 2 patches in it.)

thanks,

greg k-h

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