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

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Message-ID: <20251126-defiant-swift-of-domination-afa2c9-mkl@pengutronix.de>
Date: Wed, 26 Nov 2025 09:11:56 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Carlos Song <carlos.song@....com>
Cc: broonie@...nel.org, frank.li@....com, hawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com, 
	linux-spi@...r.kernel.org, imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: 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;
> +			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;
                                   ^
this doesn't look correct, you probably want to use a "~", right?

Marc


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