On Tue, Feb 25, 2014 at 06:54:18AM +0000, Chao Fu wrote:
> From: Chao Fu <[email protected]>
>
> DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA
> transfer driver support. Add DMA reference functions and variables to form DMA
> transfer process.
> DSPI DMA mode need work with Freescale eDMA module together.
>
> The software will be changed in two transfer methods as followwing:
> DMA PIO
> trigger write: dspi_tx_dma dspi_tx_pio
> write complete: dspi_dma_tx_complete irq_handle
> trigger read: dspi_receive_dma dspi_rx_pio
> read complete: dspi_rx_dma none
>
> Remove bitbang:
> Add DMA funtions, DSPI module need get cs change information in a spi
> transfer.
> According cs change, DSPI will give last data the right flag. Bitbang provide
> cs change behind the last data in a transfer. DSPI can not deal the last data
> in
> every transfer properly, so remove the bitbang in driver.
>
> Signed-off-by: Chao Fu <[email protected]>
> ---
> drivers/spi/Kconfig | 1 -
> drivers/spi/spi-fsl-dspi.c | 425
> ++++++++++++++++++++++++++++++++++++++-------
> 2 files changed, 360 insertions(+), 66 deletions(-)
[...]
> @@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev)
> }
> clk_prepare_enable(dspi->clk);
>
> + dspi->use_dma = of_property_read_bool(np, "use-dma");
> + if (dspi->use_dma)
> + if (dspi_request_dma(dspi)) {
> + dspi->use_dma = 0;
> + dev_err(&pdev->dev, "request dma channel fail\n");
> + dspi_release_dma(dspi);
> + }
Why have the use-dma property at all? You already fall back to PIO mode
if the DMAs are not present, so it's clearly not a requirement to use
DMA.
Why not always try to request he dmas you need? You already have the
fallback logic, the only difference would be changing the dev_err to
better describe the situation:
dev_info(&pdev->dev, "No 'tx' and/or 'rx' DMA(s), using PIO mode\n");
Cheers,
Mark.
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