Re: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On Wed, Aug 27, 2014 at 10:50 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> On 08/27/2014 11:38 AM, Andrew Bresticker wrote:
>>
>> On Mon, Aug 25, 2014 at 12:01 PM, Stephen Warren <swarren@xxxxxxxxxxxxx>
>> wrote:
>>>
>>> On 08/18/2014 11:08 AM, Andrew Bresticker wrote:
>>>>
>>>> +static int tegra_xusb_mbox_probe(struct platform_device *pdev)
>>>
>>>
>>>
>>>> +       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?
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux