Subject: [PATCH v2 2/2] [usb] add support for ACPI identification to xhci-platform

From: [email-masked] (Mark Langsdorf)
Date: Wed, 05 Nov 2014 07:59:32 -0600

On 11/04/2014 11:12 AM, Greg KH wrote:
> On Tue, Nov 04, 2014 at 10:50:33AM -0600, Mark Langsdorf wrote:
>> Provide the methods to let ACPI identify the need to use
>> xhci-platform. Change the Kconfig files so the
>> xhci-plat.o file is selectable during kernel config.
>>
>> Signed-off-by: Mark Langsdorf <[email-masked]>
>> ---
>> Changes from v1
>> 	Renamed from "add support for APM X-Gene to xhci-platform"
>> 	Removed changes to arm64/Kconfig
>> 	Made CONFIG_USB_XHCI_PLATFORM a user selectable config option
>>
>>   drivers/usb/host/Kconfig     |  7 ++++++-
>>   drivers/usb/host/xhci-plat.c | 11 +++++++++++
>>   2 files changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
>> index 82800a7..060a2361 100644
>> --- a/drivers/usb/host/Kconfig
>> +++ b/drivers/usb/host/Kconfig
>> @@ -27,7 +27,12 @@ config USB_XHCI_HCD
>>   if USB_XHCI_HCD
>>
>>   config USB_XHCI_PLATFORM
>> -	tristate
>> +	tristate "xHCI platform driver support"
>> +	--help--
>> +	  Say 'Y' to enable the support for the xHCI host controller
>> +	  as a platform device. Many ARM SoCs provide USB this way.
>> +
>> +	  If unsure, say 'Y'.
>
> You really want a 'default Y' response here?
>
> That's not good at all, what happens if I select this on a system
> without such hardware?

Based on testing with my 2 x86 systems, nothing bad, but I'll make
it 'M' because that's correct.

>>   config USB_XHCI_MVEBU
>>   	tristate "xHCI support for Marvell Armada 375/38x"
>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
>> index 91c7557..3db47ea 100644
>> --- a/drivers/usb/host/xhci-plat.c
>> +++ b/drivers/usb/host/xhci-plat.c
>> @@ -18,6 +18,7 @@
>>   #include <linux/platform_device.h>
>>   #include <linux/slab.h>
>>   #include <linux/usb/xhci_pdriver.h>
>> +#include <linux/acpi.h>
>>
>>   #include "xhci.h"
>>   #include "xhci-mvebu.h"
>> @@ -287,6 +288,15 @@ static const struct of_device_id usb_xhci_of_match[] = {
>>   MODULE_DEVICE_TABLE(of, usb_xhci_of_match);
>>   #endif
>>
>> +#ifdef CONFIG_ACPI
>> +static const struct acpi_device_id usb_xhci_acpi_match[] = {
>> +	/* APM X-Gene USB Controller */
>> +	{ "PNP0D10", },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(acpi, usb_xhci_acpi_match);
>> +#endif
>
> That looks like a very "generic" PNP value, are you sure it is assigned
> only to this specific device?

I'll adjust the comment. It is a generic PNP value and a lot of
other SoCs will use this controller.

>> +
>>   static struct platform_driver usb_xhci_driver = {
>>   	.probe	= xhci_plat_probe,
>>   	.remove	= xhci_plat_remove,
>> @@ -294,6 +304,7 @@ static struct platform_driver usb_xhci_driver = {
>>   		.name = "xhci-hcd",
>>   		.pm = DEV_PM_OPS,
>>   		.of_match_table = of_match_ptr(usb_xhci_of_match),
>> +		.acpi_match_table = ACPI_PTR(usb_xhci_acpi_match),
>
> Shouldn't the reworked driver core code handle this differently with the
> ability to handle either OF or ACPI in the same driver?

I'm not sure I understand the question. With these changes, the driver
handles both ACPI and DTB/OF. It's the same style of code as used
in drivers/ata/plat-xgene.c, which also handles both ACPI and DTB/OF.
Why do you think this code isn't correct?

--Mark Langsdorf