Re: [PATCH 2/3] SPI: spi_sh_msiof: consolidate data in 8-bit mode into 32-bit words

[Grant Likely <grant.likely@secretlab.ca>]

On Fri, Jan 21, 2011 at 04:56:42PM +0100, Guennadi Liakhovetski wrote:
> Instead of sending data 8 bits at a time in 8-bit SPI mode, swap bytes
> and send and receive them 32 bits at a time. Tested with an SD-card,
> with which this patch reduced the number of interrupts by 50%, when
> reading 5MiB of data (there are also small service packets, the number
> of interrupts, produced by 512-byte sectors should, of course, drop by
> 75%), and improved throughput by more than 40%.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Merged, thanks.

g.

> ---
>  drivers/spi/spi_sh_msiof.c |   59 ++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 59 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/spi/spi_sh_msiof.c b/drivers/spi/spi_sh_msiof.c
> index 07b4ead..658bd05 100644
> --- a/drivers/spi/spi_sh_msiof.c
> +++ b/drivers/spi/spi_sh_msiof.c
> @@ -267,6 +267,26 @@ static void sh_msiof_spi_write_fifo_32u(struct sh_msiof_spi_priv *p,
>  		sh_msiof_write(p, TFDR, get_unaligned(&buf_32[k]) << fs);
>  }
>  
> +static void sh_msiof_spi_write_fifo_s32(struct sh_msiof_spi_priv *p,
> +					const void *tx_buf, int words, int fs)
> +{
> +	const u32 *buf_32 = tx_buf;
> +	int k;
> +
> +	for (k = 0; k < words; k++)
> +		sh_msiof_write(p, TFDR, swab32(buf_32[k] << fs));
> +}
> +
> +static void sh_msiof_spi_write_fifo_s32u(struct sh_msiof_spi_priv *p,
> +					 const void *tx_buf, int words, int fs)
> +{
> +	const u32 *buf_32 = tx_buf;
> +	int k;
> +
> +	for (k = 0; k < words; k++)
> +		sh_msiof_write(p, TFDR, swab32(get_unaligned(&buf_32[k]) << fs));
> +}
> +
>  static void sh_msiof_spi_read_fifo_8(struct sh_msiof_spi_priv *p,
>  				     void *rx_buf, int words, int fs)
>  {
> @@ -317,6 +337,26 @@ static void sh_msiof_spi_read_fifo_32u(struct sh_msiof_spi_priv *p,
>  		put_unaligned(sh_msiof_read(p, RFDR) >> fs, &buf_32[k]);
>  }
>  
> +static void sh_msiof_spi_read_fifo_s32(struct sh_msiof_spi_priv *p,
> +				       void *rx_buf, int words, int fs)
> +{
> +	u32 *buf_32 = rx_buf;
> +	int k;
> +
> +	for (k = 0; k < words; k++)
> +		buf_32[k] = swab32(sh_msiof_read(p, RFDR) >> fs);
> +}
> +
> +static void sh_msiof_spi_read_fifo_s32u(struct sh_msiof_spi_priv *p,
> +				       void *rx_buf, int words, int fs)
> +{
> +	u32 *buf_32 = rx_buf;
> +	int k;
> +
> +	for (k = 0; k < words; k++)
> +		put_unaligned(swab32(sh_msiof_read(p, RFDR) >> fs), &buf_32[k]);
> +}
> +
>  static int sh_msiof_spi_bits(struct spi_device *spi, struct spi_transfer *t)
>  {
>  	int bits;
> @@ -468,9 +508,17 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
>  	int bytes_done;
>  	int words;
>  	int n;
> +	bool swab;
>  
>  	bits = sh_msiof_spi_bits(spi, t);
>  
> +	if (bits <= 8 && t->len > 15 && !(t->len & 3)) {
> +		bits = 32;
> +		swab = true;
> +	} else {
> +		swab = false;
> +	}
> +
>  	/* setup bytes per word and fifo read/write functions */
>  	if (bits <= 8) {
>  		bytes_per_word = 1;
> @@ -487,6 +535,17 @@ static int sh_msiof_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
>  			rx_fifo = sh_msiof_spi_read_fifo_16u;
>  		else
>  			rx_fifo = sh_msiof_spi_read_fifo_16;
> +	} else if (swab) {
> +		bytes_per_word = 4;
> +		if ((unsigned long)t->tx_buf & 0x03)
> +			tx_fifo = sh_msiof_spi_write_fifo_s32u;
> +		else
> +			tx_fifo = sh_msiof_spi_write_fifo_s32;
> +
> +		if ((unsigned long)t->rx_buf & 0x03)
> +			rx_fifo = sh_msiof_spi_read_fifo_s32u;
> +		else
> +			rx_fifo = sh_msiof_spi_read_fifo_s32;
>  	} else {
>  		bytes_per_word = 4;
>  		if ((unsigned long)t->tx_buf & 0x03)
> -- 
> 1.7.2.3
> 
> 
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