linux-kernel - Re: [PATCH v11 3/3] DMA: Freescale: update driver to support 8-channel DMA engine

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Date:	Thu, 7 Nov 2013 18:45:06 -0800
From:	Dan Williams <dan.j.williams@...el.com>
To:	Hongbo Zhang <hongbo.zhang@...escale.com>
Cc:	"Koul, Vinod" <vinod.koul@...el.com>, rob.herring@...xeda.com,
	pawel.moll@....com, mark.rutland@....com,
	Stephen Warren <swarren@...dotorg.org>,
	ian.campbell@...rix.com, devicetree@...r.kernel.org,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dmaengine@...r.kernel.org
Subject: Re: [PATCH v11 3/3] DMA: Freescale: update driver to support
 8-channel DMA engine

On Mon, Nov 4, 2013 at 6:31 PM, Hongbo Zhang <hongbo.zhang@...escale.com> wrote:
> Hi Vinod Koul and Dan Williams,
> Ping?
>

Not much to review from the dmaengine side, just one question below.
It would be helpful if you can send these to the new dmaengine
patchwork at dmaengine@...r.kernel.org with the Acks you have already
collected.

>
>
> On 10/17/2013 01:56 PM, Hongbo Zhang wrote:
>>
>> Hi Vinod,
>> I have gotten ACK from Mark for both the 1/3 and 2/3 patches.
>> Thanks.
>>
>>
>> On 09/26/2013 05:33 PM, hongbo.zhang@...escale.com wrote:
>>>
>>> From: Hongbo Zhang <hongbo.zhang@...escale.com>
>>>
>>> This patch adds support to 8-channel DMA engine, thus the driver works
>>> for both
>>> the new 8-channel and the legacy 4-channel DMA engines.
>>>
>>> Signed-off-by: Hongbo Zhang <hongbo.zhang@...escale.com>
>>> ---
>>>   drivers/dma/Kconfig  |    9 +++++----
>>>   drivers/dma/fsldma.c |    9 ++++++---
>>>   drivers/dma/fsldma.h |    2 +-
>>>   3 files changed, 12 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
>>> index 6825957..3979c65 100644
>>> --- a/drivers/dma/Kconfig
>>> +++ b/drivers/dma/Kconfig
>>> @@ -89,14 +89,15 @@ config AT_HDMAC
>>>         Support the Atmel AHB DMA controller.
>>>     config FSL_DMA
>>> -    tristate "Freescale Elo and Elo Plus DMA support"
>>> +    tristate "Freescale Elo series DMA support"
>>>       depends on FSL_SOC
>>>       select DMA_ENGINE
>>>       select ASYNC_TX_ENABLE_CHANNEL_SWITCH
>>>       ---help---
>>> -      Enable support for the Freescale Elo and Elo Plus DMA controllers.
>>> -      The Elo is the DMA controller on some 82xx and 83xx parts, and the
>>> -      Elo Plus is the DMA controller on 85xx and 86xx parts.
>>> +      Enable support for the Freescale Elo series DMA controllers.
>>> +      The Elo is the DMA controller on some mpc82xx and mpc83xx parts,
>>> the
>>> +      EloPlus is on mpc85xx and mpc86xx and Pxxx parts, and the Elo3 is
>>> on
>>> +      some Txxx and Bxxx parts.
>>>     config MPC512X_DMA
>>>       tristate "Freescale MPC512x built-in DMA engine support"
>>> diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
>>> index 49e8fbd..16a9a48 100644
>>> --- a/drivers/dma/fsldma.c
>>> +++ b/drivers/dma/fsldma.c
>>> @@ -1261,7 +1261,9 @@ static int fsl_dma_chan_probe(struct fsldma_device
>>> *fdev,
>>>       WARN_ON(fdev->feature != chan->feature);
>>>         chan->dev = fdev->dev;
>>> -    chan->id = ((res.start - 0x100) & 0xfff) >> 7;
>>> +    chan->id = (res.start & 0xfff) < 0x300 ?
>>> +           ((res.start - 0x100) & 0xfff) >> 7 :
>>> +           ((res.start - 0x200) & 0xfff) >> 7;
>>>       if (chan->id >= FSL_DMA_MAX_CHANS_PER_DEVICE) {

Isn't it a bit fragile to have this based on the resource address?
Can't device tree tell you the channel id directly by an index into
the "dma0: dma@...300" node?

--
Dan
--
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