On Wed, Aug 27, 2014 at 10:50 AM, Stephen Warren [off-list ref] wrote:

On 08/27/2014 11:38 AM, Andrew Bresticker wrote:

quoted

On Mon, Aug 25, 2014 at 12:01 PM, Stephen Warren [off-list ref]
wrote:

quoted

On 08/18/2014 11:08 AM, Andrew Bresticker wrote:

quoted

+static int tegra_xusb_mbox_probe(struct platform_device *pdev)

quoted

+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

+       if (!res)
+               return -ENODEV;

Should devm_request_mem_region() be called here to claim the region?

No, the xHCI host driver also needs to map these registers, so they
cannot be mapped exclusively here.

That's unfortunate. Having multiple drivers with overlapping register
regions is not a good idea. Can we instead have a top-level driver map all
the IO regions, then instantiate the various different sub-components
internally, and divide up the address space. Probably via MFD or similar.
That would prevent multiple drivers from touching the same register region.

Perhaps I'm misunderstanding, but I don't see how MFD would prevent us
from having to map this register space in two different locations -
the XUSB FPCI address space cannot be divided cleanly between host and
mailbox registers.  Or are you saying that there should be a separate
device driver that exposes an API for accessing this register space,
like the Tegra fuse or PMC drivers?