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arm64: dts: r8a7796: Add CAN/CAN FD support

Simon Horman linux-arm-kernel linux-can linux-devicetree linux-renesas-soc netdev 1 version New

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  1. v1 Latest0 of 3 patches 0 repliesNew

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Cover letter [PATCH 0/3] arm64: dts: r8a7796: Add CAN/CAN FD support

Hi Chris,

Quoted 25 lines · Chris Paterson

Hello Simon,

From: Simon Horman [mailto:horms at verge.net.au]
Sent: 23 November 2016 14:30

Quoted 21 lines · Marc Kleine-Budde
Quoted 5 lines · Chris Paterson
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This patch series adds CAN and CAN FD support to the r8a7796.

Based on renesas-devel-20161122-v4.9-rc6.

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Chris Paterson (3):
arm64: dts: r8a7796: Add CAN external clock support
arm64: dts: r8a7796: Add CAN support
arm64: dts: r8a7796: Add CAN FD support

 .../devicetree/bindings/net/can/rcar_can.txt       | 12 +++--
 .../devicetree/bindings/net/can/rcar_canfd.txt     | 12 +++--
 arch/arm64/boot/dts/renesas/r8a7796.dtsi           | 61

++++++++++++++++++++++

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 3 files changed, 75 insertions(+), 10 deletions(-)

For all three:

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Who takes this series?

I would like to see these patches split up so that the .../devicetree/bindings/ portions can go through you whole the arch/arm64/boot/dts/renesas/ portions go thorugh my renesas tree.

Okay, will do.

Thanks.

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Regarding the arch/arm64/boot/dts/renesas/ portion, I would like some consideration given to what effect enabling memory above 4Gb (64bit addressing) would have.

Can you give me some guidance here? I'm not sure what you're referring to. As far as I know the DT reg definition here is 64-bit, or are you referring to DMA usage? If the later, neither CAN driver uses DMA.

Sorry for not being clearer.

What I would like to know is if there are any problems in the CAN driver or hardware that would prevent it from functioning with memory that requires 64bit addressing present.

If the CAN hardware cannot use DMA then DMA doesn't need to be taken into account. But if it DMA could be enabled in future for CAN, for example after some driver enhancements, then it would be good to know if 64bit memory can be supported - if not it would imply DMA cannot be enabled.

As for non-DMA mode, will this function if memory above 4G is present? If not then in theory such memory couldn't be enabled if the CAN driver is enabled. This is my main concern.

Does the above help?