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

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Message-ID: <20251126-loyal-lobster-of-virtuosity-0aa824-mkl@pengutronix.de>
Date: Wed, 26 Nov 2025 13:22:55 +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_pio_transfer(struct spi_device *spi,
>  				struct spi_transfer *transfer)
>  {
> @@ -1780,9 +2112,14 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
>  	 * transfer, the SPI transfer has already been mapped, so we
>  	 * have to do the DMA transfer here.
>  	 */
> -	if (spi_imx->usedma)
> -		return spi_imx_dma_transfer(spi_imx, transfer);
> -
> +	if (spi_imx->usedma) {
> +		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);
> +		}
> +		return ret;
> +	}

Why do you do this? AFAICS the framework already does this for you see:
spi_transfer_one_message().

Marc

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