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Message-ID: <aS79MEp9LMohngIc@lizhi-Precision-Tower-5810>
Date: Tue, 2 Dec 2025 09:52:32 -0500
From: Frank Li <Frank.li@....com>
To: Carlos Song <carlos.song@....com>
Cc: mkl@...gutronix.de, broonie@...nel.org, shawnguo@...nel.org,
s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
kees@...nel.org, gustavoars@...nel.org, linux-spi@...r.kernel.org,
imx@...ts.linux.dev, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 6/6] spi: imx: enable DMA mode for target operation
On Tue, Dec 02, 2025 at 03:55:03PM +0800, Carlos Song wrote:
> Enable DMA mode for SPI IMX in target mode. Disable the word delay feature
> for target mode, because target mode should always keep high performance
> to make sure it can follow the master. Target mode continues to operate in
> dynamic burst mode.
>
> Signed-off-by: Carlos Song <carlos.song@....com>
> ---
Reviewed-by: Frank Li <Frank.Li@....com>
> drivers/spi/spi-imx.c | 77 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 57 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 045f4ffd680a..e37d786a5276 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -264,7 +264,13 @@ static bool spi_imx_can_dma(struct spi_controller *controller, struct spi_device
> if (!controller->dma_rx)
> return false;
>
> - if (spi_imx->target_mode)
> + /*
> + * Due to Freescale errata ERR003775 "eCSPI: Burst completion by Chip
> + * Select (SS) signal in Slave mode is not functional" burst size must
> + * be set exactly to the size of the transfer. This limit SPI transaction
> + * with maximum 2^12 bits.
> + */
> + if (transfer->len > MX53_MAX_TRANSFER_BYTES && spi_imx->target_mode)
> return false;
>
> if (transfer->len < spi_imx->devtype_data->fifo_size)
> @@ -1763,23 +1769,51 @@ static int spi_imx_dma_submit(struct spi_imx_data *spi_imx,
>
> transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
>
> - /* Wait SDMA to finish the data transfer.*/
> - time_left = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
> - transfer_timeout);
> - if (!time_left) {
> - dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
> - dmaengine_terminate_all(controller->dma_tx);
> - dmaengine_terminate_all(controller->dma_rx);
> - return -ETIMEDOUT;
> - }
> + if (!spi_imx->target_mode) {
> + /* Wait SDMA to finish the data transfer.*/
> + time_left = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
> + transfer_timeout);
> + if (!time_left) {
> + dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
> + dmaengine_terminate_all(controller->dma_tx);
> + dmaengine_terminate_all(controller->dma_rx);
> + return -ETIMEDOUT;
> + }
>
> - time_left = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
> - transfer_timeout);
> - if (!time_left) {
> - dev_err(&controller->dev, "I/O Error in DMA RX\n");
> - spi_imx->devtype_data->reset(spi_imx);
> - dmaengine_terminate_all(controller->dma_rx);
> - return -ETIMEDOUT;
> + time_left = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
> + transfer_timeout);
> + if (!time_left) {
> + dev_err(&controller->dev, "I/O Error in DMA RX\n");
> + spi_imx->devtype_data->reset(spi_imx);
> + dmaengine_terminate_all(controller->dma_rx);
> + return -ETIMEDOUT;
> + }
> + } else {
> + spi_imx->target_aborted = false;
> +
> + if (wait_for_completion_interruptible(&spi_imx->dma_tx_completion) ||
> + READ_ONCE(spi_imx->target_aborted)) {
> + dev_dbg(spi_imx->dev, "I/O Error in DMA TX interrupted\n");
> + dmaengine_terminate_all(controller->dma_tx);
> + dmaengine_terminate_all(controller->dma_rx);
> + return -EINTR;
> + }
> +
> + if (wait_for_completion_interruptible(&spi_imx->dma_rx_completion) ||
> + READ_ONCE(spi_imx->target_aborted)) {
> + dev_dbg(spi_imx->dev, "I/O Error in DMA RX interrupted\n");
> + dmaengine_terminate_all(controller->dma_rx);
> + return -EINTR;
> + }
> +
> + /*
> + * ECSPI has a HW issue when works in Target mode, after 64 words
> + * writtern to TXFIFO, even TXFIFO becomes empty, ECSPI_TXDATA keeps
> + * shift out the last word data, so we have to disable ECSPI when in
> + * target mode after the transfer completes.
> + */
> + if (spi_imx->devtype_data->disable)
> + spi_imx->devtype_data->disable(spi_imx);
> }
>
> return 0;
> @@ -1902,7 +1936,7 @@ static int spi_imx_dma_package_transfer(struct spi_imx_data *spi_imx,
> static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
> struct spi_transfer *transfer)
> {
> - bool word_delay = transfer->word_delay.value != 0;
> + bool word_delay = transfer->word_delay.value != 0 && !spi_imx->target_mode;
> int ret;
> int i;
>
> @@ -2108,7 +2142,7 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
> while (spi_imx->devtype_data->rx_available(spi_imx))
> readl(spi_imx->base + MXC_CSPIRXDATA);
>
> - if (spi_imx->target_mode)
> + if (spi_imx->target_mode && !spi_imx->usedma)
> return spi_imx_pio_transfer_target(spi, transfer);
>
> /*
> @@ -2120,7 +2154,10 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
> ret = spi_imx_dma_transfer(spi_imx, transfer);
> if (transfer->error & SPI_TRANS_FAIL_NO_START) {
> spi_imx->usedma = false;
> - return spi_imx_pio_transfer(spi, transfer);
> + if (spi_imx->target_mode)
> + return spi_imx_pio_transfer_target(spi, transfer);
> + else
> + return spi_imx_pio_transfer(spi, transfer);
> }
> return ret;
> }
> --
> 2.34.1
>
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