Re: [PATCH 3/3] powerpc: Dont require a dma_ops struct to set dmamask

From: Scott Wood
Date: Wed Jun 22 2011 - 13:53:31 EST

On Wed, 22 Jun 2011 07:02:56 -0500
Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx> wrote:

> The only reason to require a dma_ops struct is to see if it has
> implemented set_dma_mask. If not we can fall back to setting the mask
> directly.
> This resolves an issue with how to sequence the setting of a DMA mask
> for platform devices. Before we had an issue in that we have no way of
> setting the DMA mask before the various low level bus notifiers get
> called that might check it (swiotlb).
> So now we can do:
> pdev = platform_device_alloc("foobar", 0);
> dma_set_mask(&pdev->dev, DMA_BIT_MASK(37));
> platform_device_register(pdev);

Despite what Documentation/driver-model/platform.txt says, it looks like
platform_device_add() is what you want after platform_device_alloc().
Otherwise device_initialize() gets called twice, as would a call to the
archdata hook if one is added to platform_device_register().


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