Re: [PATCH v1 2/3] ARM: dts: tegra20: Add DMA phandle to 'fuse' node

[Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 27.09.2017 01:31, Dmitry Osipenko wrote:
> On 27.09.2017 01:10, Jon Hunter wrote:
>>
>> On 26/09/17 22:54, Dmitry Osipenko wrote:
>>> On 27.09.2017 00:25, Jon Hunter wrote:
>>>>
>>>> On 26/09/17 21:54, Jon Hunter wrote:
>>>>>
>>>>> On 25/09/17 23:35, Dmitry Osipenko wrote:
>>>>>> Currently efuse driver requests DMA channel from an arbitrary DMA device,
>>>>>> it is not a problem since there is only one DMA provider for Tegra20 yet,
>>>>>> but it will become troublesome once another provider would be added.
>>>>>>
>>>>>> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>>> ---
>>>>>>  arch/arm/boot/dts/tegra20.dtsi | 2 ++
>>>>>>  1 file changed, 2 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
>>>>>> index fb485a5e63d7..f1579c9a7ef4 100644
>>>>>> --- a/arch/arm/boot/dts/tegra20.dtsi
>>>>>> +++ b/arch/arm/boot/dts/tegra20.dtsi
>>>>>> @@ -600,6 +600,8 @@
>>>>>>  		clock-names = "fuse";
>>>>>>  		resets = <&tegra_car 39>;
>>>>>>  		reset-names = "fuse";
>>>>>> +		dmas = <&apbdma 0>;
>>>>>> +		dma-names = "fuse";
>>>>>>  	};
>>>>>>  
>>>>>>  	pcie@80003000 {
>>>>>>
>>>>>
>>>>> Acked-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>>>
>>>> Actually, request-id '0' is a valid request. Does this work ok?
>>>>
>>>
>>> It works fine, I have verified that reading on CPU == reading by DMA. The
>>> REQ_SEL 0 is "Not Assigned" and seems acts as DRQ=1. I know that it is not
>>> entirely correct, but APB DMA driver is hardcoded to the master mode, while we
>>> need slave mode.
>>
>> Looking at the TRM I see that it is 'CNTR_REQ' so I am not sure if this
>> is a timer/counter that is driving this.
>>
> 
> Oh, wow. Indeed it's TRIG_SEL is NA. Good catch! So it works because counter = 0.
> 
> Then APB DMA driver needs to be changed to support master mode. Seems that
> should be simple to change, I'll look into it.
> 

s/support master/support slave/ of course. Thank you for the review ;)

-- 
Dmitry