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SubjectRe: [PATCH 06/14] dmaengine: dma-jz4780: Add support for the JZ4725B SoC


Le lun. 9 juil. 2018 à 19:14, Vinod <vkoul@kernel.org> a écrit :
> On 03-07-18, 14:32, Paul Cercueil wrote:
>> The JZ4725B has one DMA core starring six DMA channels.
>> As for the JZ4770, each DMA channel's clock can be enabled with
>> a register write, the difference here being that once started, it
>> is not possible to turn it off.
>
> ok so disable for this, right..
>
>> @@ -204,6 +205,8 @@ static inline void
>> jz4780_dma_chan_enable(struct jz4780_dma_dev *jzdma,
>> {
>> if (jzdma->version == ID_JZ4770)
>> jz4780_dma_ctrl_writel(jzdma, JZ_DMA_REG_DCKES, BIT(chn));
>> + else if (jzdma->version == ID_JZ4725B)
>> + jz4780_dma_ctrl_writel(jzdma, JZ_DMA_REG_DCKE, BIT(chn));
>
> but you are writing to a different register here..

Yes. SoCs >= JZ4770 have the DCKE read-only register, and DCKES/DCKEC
to set/clear bits in DCKE.
On JZ4725B, DCKE is read/write, but the zeros written are ignored (at
least that's what the
documentation says).

> --
> ~Vinod

Thanks,
-Paul

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