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serial: mxs-auart: add DMA support for auart in mx28

Lauri Hintsala linux-arm-kernel linux-serial 2 versions – New

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  1. v3 Latest0 of 3 patches 0 repliesNew
  2. v23 patches 0 repliesSuperseded

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Cover letter [PATCH v3 0/3] serial: mxs-auart: add DMA support for auart in mx28

Hi Huang,

Thanks for new version. Now I don't get any errors and the CPU doesn't freeze any more but:

1) AUART corrupts data with baudrate over 1Mbits/s

2) We would need DMA support without flow control.

By the way, how do you test drivers? Is there any standard tools for uart data and throughput testing?

Lauri

Quoted 46 lines · Huang Shijie

This patch set adds the DMA support for auart in mx28.
patch 1:
In mx23, the DMA has a bug(see errata:2836). We can not add the DMA support in mx23, but we can add DMA support to auart in mx28. So in order to add the DMA support for the auart in mx28, we should add the platform_device_id to distinguish the distinguish SOCs.

patch 2: add the DMA support for mx28
Only we meet the following conditions, we can enable the DMA support for auart:
(1) We enable the DMA support in the dts file, such as arch/arm/boot/dts/imx28.dtsi.
(2) We enable the hardware flow control.
(3) We use the mx28, not the mx23. Due to hardware bug(see errata: 2836), we can not add the DMA support to mx23.

patch 3: enable the DMA support in dts for mx28
You can use the /ttyAPP0 to test this patch set. I tested this patch in mx28-evk board.

To Lauri: Please try this patch set. thanks.

v2 --> v3:
[1] fix a multi-open issue found by Lauri.

v1 --> v2:
[1] use the inline function, not a macro, to distinguish the SOCs.
[2] remove the "inline" for mxs_auart_tx_chars().
[3] use the pio, not the pio[1] to fill the DMA descriptor.
[4] use bit operation to serialize the DMA TX.
[5] use the RX/TX DMA channel to enable the DMA support, remove the "fsl,auart-enable-dma".

Huang Shijie (3):
serial: mxs-auart: distinguish the different SOCs
serial: mxs-auart: add the DMA support for mx28
ARM: dts: enable dma support for auart0 in mx28

  .../bindings/tty/serial/fsl-mxs-auart.txt          |    8 +
  arch/arm/boot/dts/imx28.dtsi                       |    1 +
  drivers/tty/serial/mxs-auart.c                     |  364 +++++++++++++++++++-
  3 files changed, 362 insertions(+), 11 deletions(-)

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