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SubjectRe: [PATCH v2] arm64: dts: rockchip: enable HDMI sound nodes for rk3328-rock64
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On 2020/08/31 4:16, Heiko Stuebner wrote:
> Hi,
>
> Am Sonntag, 2. August 2020, 17:42:31 CEST schrieb Katsuhiro Suzuki:
>> This patch enables HDMI sound (I2S0) and Analog sound (I2S1) which
>> are defined in rk3328.dtsi, and replace SPDIF nodes.
>>
>> We can use SPDIF pass-through with suitable ALSA settings and on
>> mpv or other media players.
>> - Settings: https://github.com/LibreELEC/LibreELEC.tv/blob/master/projects/Rockchip/filesystem/usr/share/alsa/cards/SPDIF.conf
>> - Ex.: mpv foo.ac3 --audio-spdif=ac3 --audio-device='alsa/SPDIF.pcm.iec958.0:SPDIF'
>>
>> [Why use simple-audio-card for SPDIF?]
>>
>> For newly adding nodes, ASoC guys recommend to use audio-graph-card.
>> But all other sound nodes for rk3328 have already been defined by
>> simple-audio-card. In this time, I chose for consistent sound nodes.
>>
>> [DMA allocation problem]
>>
>> After this patch is applied, UART2 will fail to allocate DMA resources
>> but UART driver can work fine without DMA.
>>
>> This error is related to the DMAC of rk3328 (pl330 or compatible).
>> DMAC connected to 16 DMA sources. Each sources have ID number that is
>> called 'Req number' in rk3328 TRM. After this patch is applied total 7
>> of DMA sources will be activated as follows:
>>
>> | Req number | Source | Required |
>> | | | channels |
>> |------------+--------+-----------|
>> | 8, 9 | SPI0 | 2ch |
>> | 11, 12 | I2S0 | 2ch |
>> | 14, 15 | I2S1 | 2ch |
>> | 10 | SPDIF | 1ch |
>> |------------+--------+-----------|
>> | | Total | 7ch |
>> |------------+--------+-----------|
>> | 6, 7 | UART2 | 2ch | -> cannot get DMA channels
>>
>> Due to rk3328 DMAC specification we can use max 8 channels at same
>> time. If SPI0/I2S0/I2S1/SPDIF will be activated by this patch,
>> required DMAC channels reach to 7. So the last two channels (for
>> UART2) cannot get DMA resources.
>
> Wouldn't the dma allocation depend on the probe ordering?
> Or is this predetermined, so that always uart2 looses its dmas?
>

Ah, it's depends on probe ordering when users use kernel modules...

It's better to disable DMA channels for UART2 for avoiding problem.
I'll fix and resend patch.


> Heiko
>
>
>

Best Regards,
Katsuhiro Suzuki

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