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Date:   Tue, 10 Jan 2023 14:42:52 +0300
From:   Serge Semin <fancer.lancer@gmail.com>
To:     Sudip Mukherjee <sudip.mukherjee@sifive.com>
Cc:     Mark Brown <broonie@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        jude.onyenegecha@sifive.com, ben.dooks@sifive.com,
        jeegar.lakhani@sifive.com, linux-spi@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 07/15] spi: dw: send cmd and addr to start the spi
 transfer
Message-ID: <20230110114252.eg6z5bbrhjlrg6sd@mobilestation>
References: <20221212180732.79167-1-sudip.mukherjee@sifive.com>
 <20221212180732.79167-8-sudip.mukherjee@sifive.com>
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On Mon, Dec 12, 2022 at 06:07:24PM +0000, Sudip Mukherjee wrote:
> In enhanced spi mode, read or write will start by sending the cmd
> and address (if present).
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
> ---
>  drivers/spi/spi-dw-core.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
> index 06169aa3f37bf..ecab0fbc847c7 100644
> --- a/drivers/spi/spi-dw-core.c
> +++ b/drivers/spi/spi-dw-core.c
> @@ -832,6 +832,29 @@ static void dw_spi_init_enh_mem_buf(struct dw_spi *dws, const struct spi_mem_op
>  	}
>  }
>  
> +static void dw_spi_enh_write_cmd_addr(struct dw_spi *dws, const struct spi_mem_op *op)
> +{
> +	void *buf = dws->buf;
> +	u32 txw;
> +

> +	/* Send cmd as 32 bit value */
> +	if (buf) {
> +		txw = *(u32 *)(buf);
> +		dw_write_io_reg(dws, DW_SPI_DR, txw);
> +		buf += dws->reg_io_width;
> +		if (op->addr.nbytes) {
> +			txw = *(u32 *)(buf);
> +			dw_write_io_reg(dws, DW_SPI_DR, txw);
> +			if (op->addr.nbytes > 4) {
> +				/* address more than 32bit */
> +				buf += dws->reg_io_width;
> +				txw = *(u32 *)(buf);
> +				dw_write_io_reg(dws, DW_SPI_DR, txw);
> +			}
> +		}
> +	}

Just put the command and address directly to the CSR. There is no
point in using the temporary buffer in your case unless I miss
something.

-Serge(y)

> +}
> +
>  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;
> @@ -886,6 +909,8 @@ static int dw_spi_exec_enh_mem_op(struct spi_mem *mem, const struct spi_mem_op *
>  
>  	dw_spi_enable_chip(dws, 1);
>  
> +	dw_spi_enh_write_cmd_addr(dws, op);
> +
>  	return 0;
>  }
>  
> -- 
> 2.30.2
>