[U-Boot] [v2 3/6] spi: cadence_qspi: remove sram polling from flash write

[Marek Vasut]

On Thursday, July 16, 2015 at 04:27:31 AM, Vikas Manocha wrote:
> There is no need to poll sram level before writing to flash, data going to
> SRAM till sram is full, after that backpressure will take over.

Please see the question I posed in 2/6 v2 .

> Signed-off-by: Vikas Manocha <vikas.manocha at st.com>
> ---
> 
> Changes in v2: Rebased to master
> 
>  drivers/spi/cadence_qspi_apb.c |   61
> ++++++++++------------------------------ 1 file changed, 15 insertions(+),
> 46 deletions(-)
> 
> diff --git a/drivers/spi/cadence_qspi_apb.c
> b/drivers/spi/cadence_qspi_apb.c index 487bbef..ad8b79a 100644
> --- a/drivers/spi/cadence_qspi_apb.c
> +++ b/drivers/spi/cadence_qspi_apb.c
> @@ -214,67 +214,36 @@ static int cadence_qspi_apb_read_fifo_data(void
> *dest, return 0;
>  }
> 
> -static void cadence_qspi_apb_write_fifo_data(const void *dest_ahb_addr,
> -	const void *src, unsigned int bytes)
> -{
> -	unsigned int temp = 0;
> -	int i;
> -	int remaining = bytes;
> -	unsigned int *dest_ptr = (unsigned int *)dest_ahb_addr;
> -	unsigned int *src_ptr = (unsigned int *)src;
> -
> -	while (remaining >= CQSPI_FIFO_WIDTH) {
> -		for (i = CQSPI_FIFO_WIDTH/sizeof(src_ptr) - 1; i >= 0; i--)
> -			writel(*(src_ptr+i), dest_ptr+i);
> -		src_ptr += CQSPI_FIFO_WIDTH/sizeof(src_ptr);
> -		remaining -= CQSPI_FIFO_WIDTH;
> -	}
> -	if (remaining) {
> -		/* dangling bytes */
> -		i = remaining/sizeof(dest_ptr);
> -		memcpy(&temp, src_ptr+i, remaining % sizeof(dest_ptr));
> -		writel(temp, dest_ptr+i);
> -		for (--i; i >= 0; i--)
> -			writel(*(src_ptr+i), dest_ptr+i);
> -	}
> -	return;
> -}
> -
>  /* Write to SRAM FIFO with polling SRAM fill level. */
>  static int qpsi_write_sram_fifo_push(struct cadence_spi_platdata *plat,
>  				const void *src_addr, unsigned int num_bytes)
>  {
> -	const void *reg_base = plat->regbase;
> -	void *dest_addr = plat->ahbbase;
> -	unsigned int retry = CQSPI_REG_RETRY;
> -	unsigned int sram_level;
> +	int i = 0;
> +	unsigned int *dest_addr = plat->ahbbase;
>  	unsigned int wr_bytes;
> -	unsigned char *src = (unsigned char *)src_addr;
> +	unsigned int *src_ptr = (unsigned int *)src_addr;
>  	int remaining = num_bytes;
>  	unsigned int page_size = plat->page_size;
> -	unsigned int sram_threshold_words = CQSPI_REG_SRAM_THRESHOLD_WORDS;
> 
>  	while (remaining > 0) {
> -		retry = CQSPI_REG_RETRY;
> -		while (retry--) {
> -			sram_level = CQSPI_GET_WR_SRAM_LEVEL(reg_base);
> -			if (sram_level <= sram_threshold_words)
> -				break;
> -		}
> -		if (!retry) {
> -			printf("QSPI: SRAM fill level (0x%08x) not hit lower 
expected level
> (0x%08x)", -			       sram_level, sram_threshold_words);
> -			return -1;
> -		}
>  		/* Write a page or remaining bytes. */
>  		wr_bytes = (remaining > page_size) ?
>  					page_size : remaining;
> 
> -		cadence_qspi_apb_write_fifo_data(dest_addr, src, wr_bytes);
> -		src += wr_bytes;
>  		remaining -= wr_bytes;
> +		while (wr_bytes >= CQSPI_FIFO_WIDTH) {
> +			for (i = 0; i < CQSPI_FIFO_WIDTH/sizeof(dest_addr); i++)
> +				writel(*(src_ptr+i), dest_addr+i);

Why don't you use memcpy instead , didn't you say you're copying data to/from 
SRAM? Is src_ptr value always aligned ?

> +			src_ptr += CQSPI_FIFO_WIDTH/sizeof(dest_addr);
> +			wr_bytes -= CQSPI_FIFO_WIDTH;
> +		}
> +		if (wr_bytes) {
> +			/* dangling bytes */
> +			i = wr_bytes/sizeof(dest_addr);
> +			for (i = wr_bytes/sizeof(dest_addr); i >= 0; i--)
> +				writel(*(src_ptr+i), dest_addr+i);
> +		}
>  	}
> -
>  	return 0;
>  }