linux-kernel - Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

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Date:	Thu, 17 Dec 2015 13:57:19 -0400
From:	Julian Margetson <runaway@...dw.ms>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Måns Rullgård <mans@...sr.com>
Cc:	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find
 dma channel

On 12/17/2015 12:53 PM, Andy Shevchenko wrote:
> On Thu, 2015-12-17 at 16:04 +0000, Måns Rullgård wrote:
>> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>>
>>> On Thu, 2015-12-17 at 15:13 +0000, Måns Rullgård wrote:
>>>> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>>>>
>>>>> On Tue, 2015-12-15 at 23:34 +0000, Måns Rullgård wrote:
>>>>>> Mans Rullgard <mans@...sr.com> writes:
>>>>>>
>>>>>>> Currently this driver only works with a DesignWare DMA
>>>>>>> engine
>>>>>>> which it registers manually using the second "reg" address
>>>>>>> range and interrupt number from the DT node.
>>>>>>>
>>>>>>> This patch makes the driver instead use the "dmas" property
>>>>>>> if
>>>>>>> present, otherwise optionally falling back on the old way
>>>>>>> so
>>>>>>> existing device trees can continue to work.
>>>>>>>
>>>>>>> With this change, there is no longer any reason to depend
>>>>>>> on
>>>>>>> the 460EX machine type so drop that from Kconfig.
>>>>>>>
>>>>>>> Signed-off-by: Mans Rullgard <mans@...sr.com>
>>>>>>> ---
>>>>>>>   drivers/ata/Kconfig          |  10 ++-
>>>>>>>   drivers/ata/sata_dwc_460ex.c | 192
>>>>>>> +++++++++++++++++++++++++++--
>>>>>>> --------------
>>>>>>>   2 files changed, 131 insertions(+), 71 deletions(-)
>>>>>> The corresponding patch for the canyonlands devicetree looks
>>>>>> something
>>>>>> like this.  I don't have any such hardware or even a manual,
>>>>>> so I
>>>>>> don't
>>>>>> know what values to use for the various required DT
>>>>>> properties of
>>>>>> the
>>>>>> DMA controller node, nor can I test it.  The SATA driver
>>>>>> works
>>>>>> with a
>>>>>> different DMA controller on a Sigma Designs chip.
>>>>>>
>>>>>> diff --git a/arch/powerpc/boot/dts/canyonlands.dts
>>>>>> b/arch/powerpc/boot/dts/canyonlands.dts
>>>>>> index 3dc75de..959f36e 100644
>>>>>> --- a/arch/powerpc/boot/dts/canyonlands.dts
>>>>>> +++ b/arch/powerpc/boot/dts/canyonlands.dts
>>>>>> @@ -190,12 +190,22 @@
>>>>>>   					 /* DMA */ 0x2 &UIC0
>>>>>> 0xc
>>>>>> 0x4>;
>>>>>>   		};
>>>>>>   
>>>>>> +		DMA0: dma@...d0800 {
>>>>>> +			compatible = "snps,dma-spear1340";
>>>>>> +			reg = <4 0xbffd0800 0x400>;
>>>>>> +			interrupt-parent = <&UIC3>;
>>>>>> +			interrupts = <0x5 0x4>;
>>>>>> +			#dma-cells = <3>;
>>>>>> +			/* required properties here */
>>>>> You have to move the master assignments and other custom
>>>>> dw_dmac
>>>>> properties. Maybe at some point I will fix that in
>>>>> dw/platform.c.
>>>>>
>>>>>> +		};
>>>> The current sata_dwc driver calls dw_dma_probe() with null pdata
>>>> which causes the dw_dma driver to auto-detect most
>>>> parameters.  It
>>>> looks like simply omitting those properties here results in the
>>>> same
>>>> thing, although in this case dw_dma_parse_dt() leaves a
>>>> devm-allocated pdata struct adrift.  Deferring the allocation of
>>>> that
>>>> and changing the DT binding doc to make these properties optional
>>>> for
>>>> auto-detect-capable hardware should just work.
>>> Yeah, I would like to allow autoconfiguration in case of DT as well
>>> and
>>> translate it to use unified device property API.
>>>
>>>> Something like this:
>>> If it works for you, please, submit as a patch. Thanks.
>> I can't test it since I have no such hardware.
> It's currently broken, last person who seems to have it is
> (was?) Julian Margetson [1]
>
> [1] https://patchwork.ozlabs.org/patch/439850/
>
I have been running my machine mostly configured for pciex1  thus with 
the sata_dwc disabled.
The changes to sata_dwc-460ex do cause an oops.
I will try to give more detailed info over this weekend .


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