[EXT] Re: [PATCH 5/6] spi: imx: support dynamic burst length for ECSPI DMA mode

[Carlos Song]

> -----Original Message-----
> From: Marc Kleine-Budde <mkl at pengutronix.de>
> Sent: Wednesday, November 26, 2025 4:20 PM
> To: Carlos Song <carlos.song at nxp.com>
> Cc: broonie at kernel.org; Frank Li <frank.li at nxp.com>; hawnguo at kernel.org;
> s.hauer at pengutronix.de; kernel at pengutronix.de; festevam at gmail.com;
> linux-spi at vger.kernel.org; imx at lists.linux.dev;
> linux-arm-kernel at lists.infradead.org; linux-kernel at vger.kernel.org
> Subject: [EXT] Re: [PATCH 5/6] spi: imx: support dynamic burst length for ECSPI
> DMA mode
> 
> On 25.11.2025 18:06:17, Carlos Song wrote:
> > +static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
> > +				struct spi_transfer *transfer)
> > +{
> > +	bool word_delay = transfer->word_delay.value != 0;
> > +	int ret;
> > +	int i;
> > +
> > +	ret = spi_imx_dma_data_prepare(spi_imx, transfer, word_delay);
> > +	if (ret < 0) {
> > +		transfer->error |= SPI_TRANS_FAIL_NO_START;
> > +		dev_err(spi_imx->dev, "DMA data prepare fail\n");
> > +		goto fallback_pio;
> > +	}
> > +
> > +	spi_imx->rx_offset = 0;
> > +
> > +	/* Each dma_package performs a separate DMA transfer once */
> > +	for (i = 0; i < spi_imx->dma_package_num; i++) {
> > +		ret = spi_imx_dma_map(spi_imx, &spi_imx->dma_data[i]);
> > +		if (ret < 0) {
> > +			transfer->error |= SPI_TRANS_FAIL_NO_START;
> 
> What about:
> 
> if (i == 0)
>         transfer->error |= SPI_TRANS_FAIL_NO_START;
> 
> instead of removing the later?

	for (i = 0; i < spi_imx->dma_package_num; i++) {
		ret = spi_imx_dma_map(spi_imx, &spi_imx->dma_data[i]);
		if (ret < 0) {
			if (I == 0)
				transfer->error |= SPI_TRANS_FAIL_NO_START;
			dev_err(spi_imx->dev, "DMA map fail\n");
			break;
		}
...
-	/* If no any dma package data is transferred, fallback to PIO mode transfer */
-	if ((transfer->error & SPI_TRANS_FAIL_NO_START) && i != 0)
-		transfer->error &= !SPI_TRANS_FAIL_NO_START;

	return ret;

Just like this? I accept this. I can fix this in V2
> > +			dev_err(spi_imx->dev, "DMA map fail\n");
> > +			break;
> > +		}
> > +
> > +		/* Update the CTRL register BL field */
> > +		writel(spi_imx->dma_data[i].cmd_word, spi_imx->base +
> MX51_ECSPI_CTRL);
> > +
> > +		ret = spi_imx_dma_package_transfer(spi_imx,
> &spi_imx->dma_data[i],
> > +						   transfer, word_delay);
> > +
> > +		/* Whether the dma transmission is successful or not, dma unmap is
> necessary */
> > +		spi_imx_dma_unmap(spi_imx, &spi_imx->dma_data[i]);
> > +
> > +		if (ret < 0) {
> > +			dev_dbg(spi_imx->dev, "DMA %d transfer not really finish\n", i);
> > +			break;
> > +		}
> > +	}
> > +
> > +	for (int j = 0; j < spi_imx->dma_package_num; j++) {
> > +		kfree(spi_imx->dma_data[j].dma_tx_buf);
> > +		kfree(spi_imx->dma_data[j].dma_rx_buf);
> > +	}
> > +	kfree(spi_imx->dma_data);
> > +
> > +fallback_pio:
> > +	/* If no any dma package data is transferred, fallback to PIO mode transfer
> */
> > +	if ((transfer->error & SPI_TRANS_FAIL_NO_START) && i != 0)
> > +		transfer->error &= !SPI_TRANS_FAIL_NO_START;
> > +
> > +	return ret;
> > +}
> > +
> 
> Marc
> 
> --
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