[PATCH v4 2/2] mtd: nand: sunxi: Set serial access mode correctly

[boris.brezillon@free-electrons.com (Boris Brezillon)]

On Thu, 11 Jun 2015 16:57:17 +0200
Roy Spliet <r.spliet@ultimaker.com> wrote:

> Replaces the hard coded "always use EDO" policy with that prescribed
> by the ONFI 3.1 specification that EDO mode should always be used if tRC
> is below 30ns.
> 
> Signed-off-by: Roy Spliet <r.spliet@ultimaker.com>

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

Thanks,

Boris

> 
> V4:
> - Simplify by pre-calculating the entire timing CTL register value
> ---
>  drivers/mtd/nand/sunxi_nand.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> index 79de4ef..26df48f 100644
> --- a/drivers/mtd/nand/sunxi_nand.c
> +++ b/drivers/mtd/nand/sunxi_nand.c
> @@ -99,6 +99,9 @@
>  				 NFC_CMD_INT_ENABLE | \
>  				 NFC_DMA_INT_ENABLE)
>  
> +/* define bit use in NFC_TIMING_CTL */
> +#define NFC_TIMING_CTL_EDO	BIT(8)
> +
>  /* define NFC_TIMING_CFG register layout */
>  #define NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD)		\
>  	((tWB) & 0x3) | (((tADL) & 0x3) << 2) |			\
> @@ -226,6 +229,7 @@ struct sunxi_nand_chip {
>  	struct mtd_info mtd;
>  	unsigned long clk_rate;
>  	u32 timing_cfg;
> +	u32 timing_ctl;
>  	int selected;
>  	int nsels;
>  	struct sunxi_nand_chip_sel sels[0];
> @@ -412,6 +416,7 @@ static void sunxi_nfc_select_chip(struct mtd_info *mtd, int chip)
>  		}
>  	}
>  
> +	writel(sunxi_nand->timing_ctl, nfc->regs + NFC_REG_TIMING_CTL);
>  	writel(sunxi_nand->timing_cfg, nfc->regs + NFC_REG_TIMING_CFG);
>  	writel(ctl, nfc->regs + NFC_REG_CTL);
>  
> @@ -941,6 +946,13 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
>  	/* TODO: A83 has some more bits for CDQSS, CS, CLHZ, CCS, WC */
>  	chip->timing_cfg = NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD);
>  
> +	/*
> +	 * ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data
> +	 * output cycle timings shall be used if the host drives tRC less than
> +	 * 30 ns.
> +	 */
> +	chip->timing_ctl = (timings->tRC_min < 30000) ? NFC_TIMING_CTL_EDO : 0;
> +
>  	/* Convert min_clk_period from picoseconds to nanoseconds */
>  	min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
>  
> @@ -1442,11 +1454,6 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, nfc);
>  
> -	/*
> -	 * TODO: replace this magic value with EDO flag
> -	 */
> -	writel(0x100, nfc->regs + NFC_REG_TIMING_CTL);
> -
>  	ret = sunxi_nand_chips_init(dev, nfc);
>  	if (ret) {
>  		dev_err(dev, "failed to init nand chips\n");



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com