Re: [PATCH v10] dmaengine: Add MOXA ART DMA engine driver

Re: [PATCH v10] dmaengine: Add MOXA ART DMA engine driver

[Mark Rutland]

[adding devicetree]

On Mon, Oct 07, 2013 at 03:10:34PM +0100, Jonas Jensen wrote:
> The MOXA ART SoC has a DMA controller capable of offloading expensive
> memory operations, such as large copies. This patch adds support for
> the controller including four channels. Two of these are used to
> handle MMC copy on the UC-7112-LX hardware. The remaining two can be
> used in a future audio driver or client application.
> 
> Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
> ---
> 
> Notes:
>     Changes since v9:
> 
>     1. reorder probe path, also move dma_async_device_register() to happen after devm_request_irq()
> 
>     Applies to next-20130927
> 
>  .../devicetree/bindings/dma/moxa,moxart-dma.txt    |  19 +
>  drivers/dma/Kconfig                                |   7 +
>  drivers/dma/Makefile                               |   1 +
>  drivers/dma/moxart-dma.c                           | 651 +++++++++++++++++++++
>  4 files changed, 678 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
>  create mode 100644 drivers/dma/moxart-dma.c
> 
> diff --git a/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt b/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
> new file mode 100644
> index 0000000..79facce
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
> @@ -0,0 +1,19 @@
> +MOXA ART DMA Controller
> +
> +See dma.txt first
> +
> +Required properties:
> +
> +- compatible : Must be "moxa,moxart-dma"

Sorry I didn't notice this previously, but "moxa" isn't in
Documentation/devicetree/bindings/vendor-prefixes.txt (despite several
bindings using it). Could you cook up a separate patch to add an entry
for Moxa, please?

Also, given the SoC is called "ART" it's a shame that we're calling this
"moxa,moxart-dma" rather than "moxa,art-dma". We already have precedent
for "moxart" in bindings though, so changing that's likely to lead to
more problems.

> +- reg :                Should contain registers location and length
> +- interrupts : Should contain the interrupt number

Sorry for yet more pendantry, but could we instead have:

 - interrupts: Should contain an interrupt-specifier for the sole
               interrupt generated by the device.

> +- #dma-cells : Should be 1, a single cell holding a line request number
> +
> +Example:
> +
> +       dma: dma@90500000 {
> +               compatible = "moxa,moxart-dma";
> +               reg = <0x90500080 0x40>;
> +               interrupts = <24 0>;
> +               #dma-cells = <1>;
> +       };

Otherwise I think the binding looks OK.

Thanks,
Mark

Re: [PATCH v10] dmaengine: Add MOXA ART DMA engine driver

[Jonas Jensen]

On 7 October 2013 17:12, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> wrote:
> Sorry I didn't notice this previously, but "moxa" isn't in
> Documentation/devicetree/bindings/vendor-prefixes.txt (despite several
> bindings using it). Could you cook up a separate patch to add an entry
> for Moxa, please?

Yes, I'll submit a separate patch.

> Also, given the SoC is called "ART" it's a shame that we're calling this
> "moxa,moxart-dma" rather than "moxa,art-dma". We already have precedent
> for "moxart" in bindings though, so changing that's likely to lead to
> more problems.

Sorry about that, I think the "moxart" contraction was suggested and
has been sticky ever since.

It's at least a little appropriate because the physical chip text
reads "MOXA ART" (photo):

https://lh4.googleusercontent.com/-A-2FXDrObU8/UMcMc_K2vEI/AAAAAAAABwg/ldaLZ7ps1P4/w1331-h998-no/UC-7112-LX-picture4.jpg

Currently three drivers in linux-next use the name with accompanying
device tree bindings.
Considering the amount of patches required, can we keep the name, please?

> Sorry for yet more pendantry, but could we instead have:
>
>  - interrupts: Should contain an interrupt-specifier for the sole
>                interrupt generated by the device.

Fixed in v11.


Regards,
Jonas
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Re: [PATCH v10] dmaengine: Add MOXA ART DMA engine driver

[Mark Rutland]

On Tue, Oct 08, 2013 at 10:53:36AM +0100, Jonas Jensen wrote:
> On 7 October 2013 17:12, Mark Rutland <mark.rutland@arm.com> wrote:
> > Sorry I didn't notice this previously, but "moxa" isn't in
> > Documentation/devicetree/bindings/vendor-prefixes.txt (despite several
> > bindings using it). Could you cook up a separate patch to add an entry
> > for Moxa, please?
> 
> Yes, I'll submit a separate patch.

Cheers.

> 
> > Also, given the SoC is called "ART" it's a shame that we're calling this
> > "moxa,moxart-dma" rather than "moxa,art-dma". We already have precedent
> > for "moxart" in bindings though, so changing that's likely to lead to
> > more problems.
> 
> Sorry about that, I think the "moxart" contraction was suggested and
> has been sticky ever since.
> 
> It's at least a little appropriate because the physical chip text
> reads "MOXA ART" (photo):
> 
> https://lh4.googleusercontent.com/-A-2FXDrObU8/UMcMc_K2vEI/AAAAAAAABwg/ldaLZ7ps1P4/w1331-h998-no/UC-7112-LX-picture4.jpg
> 
> Currently three drivers in linux-next use the name with accompanying
> device tree bindings.
> Considering the amount of patches required, can we keep the name, please?

Yeah, I think we have to keep it. It's not objectively wrong, and we
have other contractions (e.g. vexpress) in bindings. It just looks a bit
more odd than the others due to the repetition of "moxa". There's no
benefit to be had changing it now.

> 
> > Sorry for yet more pendantry, but could we instead have:
> >
> >  - interrupts: Should contain an interrupt-specifier for the sole
> >                interrupt generated by the device.
> 
> Fixed in v11.

Sounds good.

Cheers,
Mark.