linux-kernel - Re: [PATCH v2 12/15] spi: dw: Add retry for enhanced spi mode

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Message-ID: <20230110121016.apwgvjhhkkxrmvrq@mobilestation>
Date:   Tue, 10 Jan 2023 15:10:16 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Sudip Mukherjee <sudip.mukherjee@...ive.com>
Cc:     Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        jude.onyenegecha@...ive.com, ben.dooks@...ive.com,
        jeegar.lakhani@...ive.com, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 12/15] spi: dw: Add retry for enhanced spi mode

On Mon, Dec 12, 2022 at 06:07:29PM +0000, Sudip Mukherjee wrote:
> If the connection to the spi device is not stable then the transfer can
> fail. Add retry for DW_SPI_WAIT_RETRIES times and print error if it still
> fails.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@...ive.com>
> ---
>  drivers/spi/spi-dw-core.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index dff7b419af304..cef56acd8d8fd 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -906,7 +906,7 @@ static void dw_spi_enh_write_cmd_addr(struct dw_spi *dws, const struct spi_mem_o
>  	}
>  }
>  
> -static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +static int dw_spi_try_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
>  {
>  	struct spi_controller *ctlr = mem->spi->controller;
>  	struct dw_spi *dws = spi_controller_get_devdata(ctlr);
> @@ -991,6 +991,21 @@ static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *
>  	return ret;
>  }
>  

> +static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	struct spi_controller *ctlr = mem->spi->controller;
> +	struct dw_spi *dws = spi_controller_get_devdata(ctlr);
> +	int retry, ret = -EIO;
> +
> +	for (retry = 0; retry < DW_SPI_WAIT_RETRIES && ret != 0; retry++)
> +		ret = dw_spi_try_enh_mem_op(mem, op);
> +
> +	if (retry == DW_SPI_WAIT_RETRIES)
> +		dev_err(&dws->master->dev, "Retry of enh_mem_op failed\n");
> +
> +	return ret;

No. If something goes wrong during the transfer you should return an
error and let the upper layer to decide whether to retry or pass the
failure further.

-Serge(y)

> +}
> +
>  /*
>   * Initialize the default memory operations if a glue layer hasn't specified
>   * custom ones. Direct mapping operations will be preserved anyway since DW SPI
> -- 
> 2.30.2
>