Re: [PATCH] dmaengine: idxd: add module parameter to force disable of SVA

Dave Jiang
2021-01-19T19:45:35Z

On 1/19/2021 9:38 AM, Vinod Koul wrote:
> On 18-01-21, 10:06, Dave Jiang wrote:
>> On 1/16/2021 11:51 PM, Vinod Koul wrote:
>>> On 15-01-21, 15:01, Dave Jiang wrote:
>>>> Add a module parameter that overrides the SVA feature enabling. This keeps
>>>> the driver in legacy mode even when intel_iommu=sm_on is set. In this mode,
>>>> the descriptor fields must be programmed with dma_addr_t from the Linux DMA
>>>> API for source, destination, and completion descriptors.
>>>>
>>>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>>>> ---
>>>> drivers/dma/idxd/init.c | 8 +++++++-
>>>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
>>>> index 25cc947c6179..9687a24ff982 100644
>>>> --- a/drivers/dma/idxd/init.c
>>>> +++ b/drivers/dma/idxd/init.c
>>>> @@ -26,6 +26,10 @@ MODULE_VERSION(IDXD_DRIVER_VERSION);
>>>> MODULE_LICENSE("GPL v2");
>>>> MODULE_AUTHOR("Intel Corporation");
>>>> +static bool sva = true;
>>>> +module_param(sva, bool, 0644);
>>>> +MODULE_PARM_DESC(sva, "Toggle SVA support on/off");
>>> Documentation for this please..
>> Just comments or is there somewhere specific for driver module parameter
>> documentations?
> All the parameters are supposed to be documented in Documentation/admin-guide/kernel-parameters.txt

It seems to be for core kernel components and subsystems, and not
specific device drivers. I'm not seeing any of the dmaengine driver
module params being in this doc after grepping in drivers/dma.

>
> Thanks
>