linux-kernel - Re: [PATCH 2/2] spi: a3700: Remove endianness swapping for full-duplex transfers

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Message-ID: <87fu6v49ol.fsf@free-electrons.com>
Date:   Wed, 24 Jan 2018 15:23:54 +0100
From:   Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:     Maxime Chevallier <maxime.chevallier@...le.fr>
Cc:     broonie@...nel.org, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] spi: a3700: Remove endianness swapping for full-duplex transfers

Hi Maxime,
 
 On mer., janv. 24 2018, Maxime Chevallier <maxime.chevallier@...le.fr> wrote:

> Fixes the following sparse warnings :
> line 767: warning: incorrect type in assignment (different base types)
> line 767:    expected unsigned int [unsigned] [assigned] [usertype] val_out
> line 767:    got restricted __le32 [usertype] <noident>
> line 776: warning: cast to restricted __le32
>
> This takes advantage of readl/writel to do the endianness reordering,
> and removes an extra variable in the function.
>
> Fixes: f68a7dcb91b7 ("spi: a3700: Add full-duplex support")
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...le.fr>

As for the previous patch:

Reviewed-by: Gregory CLEMENT <gregory.clement@...e-electrons.com>

Thanks,

Gregory> ---
>  drivers/spi/spi-armada-3700.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/spi/spi-armada-3700.c b/drivers/spi/spi-armada-3700.c
> index 43ee0b56fe1c..7dcb14d303eb 100644
> --- a/drivers/spi/spi-armada-3700.c
> +++ b/drivers/spi/spi-armada-3700.c
> @@ -747,7 +747,7 @@ static int a3700_spi_transfer_one_full_duplex(struct spi_master *master,
>  				  struct spi_transfer *xfer)
>  {
>  	struct a3700_spi *a3700_spi = spi_master_get_devdata(master);
> -	u32 val_in, val_out;
> +	u32 val;
>  
>  	/* Disable FIFO mode */
>  	a3700_spi_fifo_mode_set(a3700_spi, false);
> @@ -761,21 +761,20 @@ static int a3700_spi_transfer_one_full_duplex(struct spi_master *master,
>  			a3700_spi_bytelen_set(a3700_spi, 1);
>  
>  		if (a3700_spi->byte_len == 1)
> -			val_out = *a3700_spi->tx_buf;
> +			val = *a3700_spi->tx_buf;
>  		else
> -			val_out = cpu_to_le32(*(u32 *)a3700_spi->tx_buf);
> +			val = *(u32 *)a3700_spi->tx_buf;
>  
> -		spireg_write(a3700_spi, A3700_SPI_DATA_OUT_REG, val_out);
> +		spireg_write(a3700_spi, A3700_SPI_DATA_OUT_REG, val);
>  
>  		/* Wait for all the data to be shifted in / out */
>  		while (!(spireg_read(a3700_spi, A3700_SPI_IF_CTRL_REG) &
>  				A3700_SPI_XFER_DONE))
>  			cpu_relax();
>  
> -		val_in = le32_to_cpu(spireg_read(a3700_spi,
> -						 A3700_SPI_DATA_IN_REG));
> +		val = spireg_read(a3700_spi, A3700_SPI_DATA_IN_REG);
>  
> -		memcpy(a3700_spi->rx_buf, &val_in, a3700_spi->byte_len);
> +		memcpy(a3700_spi->rx_buf, &val, a3700_spi->byte_len);
>  
>  		a3700_spi->buf_len -= a3700_spi->byte_len;
>  		a3700_spi->tx_buf += a3700_spi->byte_len;
> -- 
> 2.1.4
>

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com