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List:       linux-spi
Subject:    RE: ECSPI Slave on i.M8M Mini with DMA
From:       Peng Fan <peng.fan () nxp ! com>
Date:       2021-06-30 9:34:45
Message-ID: DB6PR0402MB27601D0F4FB77F0007EDF0E888019 () DB6PR0402MB2760 ! eurprd04 ! prod ! outlook ! com
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> Subject: ECSPI Slave on i.M8M Mini with DMA

Clark may help on this.

Regards,
Peng.

> 
> To the NXP team,
> 
> I noticed the spi-imx driver has a function called spi_imx_can_dma() which
> returns false if the SPI is configured as a slave, so the dma cannot be used in
> slave mode.
> 
> Section 10.1.2.7 "DMA" of the The 8MM Ref manual, Rev 3, shows there are a
> few conditions that can trigger the DMA.  Of them, two are RXFIFO data
> request and RXFIFO full.  The block diagram in that section shows it can
> retrieve data with DMA
> 
> However, in section 10.1.4 "Applications" of the same document, it shows the
> optional DMA configurations are only in the SPI master configuration and not
> the SPI slave configuration.
> 
> The ECSPIx_DMAREG documentation (section 10.1.5.6) states "The ECSPI
> sends out DMA requests when the appropriate FIFO conditions are matched."
> Unfortunately it doesn't explicitly state whether that's only for master or
> available in either master or slave mode.
> 
> Can someone tell me if DMA is available when SPI is configured as a slave?
> 
> thank you,
> 
> adam

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