Re: [PATCH 02/16] mtd: nand: sunxi: fix clk rate calculation

Thomas Petazzoni
2016-03-08T14:58:19Z

Boris,

On Mon, 7 Mar 2016 17:18:19 +0100, Boris Brezillon wrote:
> Unlike what is specified in the Allwinner datasheets, the NAND clock rate
> is not equal to 2/T but 1/T. Fix the clock rate selection accordingly.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
> drivers/mtd/nand/sunxi_nand.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> index 4d01e65..ab66d8d 100644
> --- a/drivers/mtd/nand/sunxi_nand.c
> +++ b/drivers/mtd/nand/sunxi_nand.c
> @@ -1208,13 +1208,7 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
> /* Convert min_clk_period from picoseconds to nanoseconds */
> min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
>
> - /*
> - * Convert min_clk_period into a clk frequency, then get the
> - * appropriate rate for the NAND controller IP given this formula
> - * (specified in the datasheet):
> - * nand clk_rate = 2 * min_clk_rate
> - */

When some HW works in a way that is *NOT* the one specified in the
datasheet, I think you should rather add *more* comments about this
aspect, rather than removing existing comments.

Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering