On Fri, Jun 20, 2008 at 05:38:17PM +0800, Chen Gong wrote:
> Signed-off-by: Chen Gong <[EMAIL PROTECTED]>
The patch lacks any description. E.g. at which frequencies the current
math breaks, and why?
> ---
> drivers/spi/spi_mpc83xx.c | 29 ++++++++++++++++-------------
> 1 files changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
> index 6832da6..070c621 100644
> --- a/drivers/spi/spi_mpc83xx.c
> +++ b/drivers/spi/spi_mpc83xx.c
> @@ -266,21 +266,24 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi,
> struct spi_transfer *t)
>
> cs->hw_mode |= SPMODE_LEN(bits_per_word);
>
> - if ((mpc83xx_spi->spibrg / hz) >= 64) {
> - pm = mpc83xx_spi->spibrg / (hz * 64) - 1;
> - if (pm > 0x0f) {
> - dev_err(&spi->dev, "Requested speed is too "
> - "low: %d Hz. Will use %d Hz instead.\n",
> - hz, mpc83xx_spi->spibrg / 1024);
> - pm = 0x0f;
> + if ((mpc83xx_spi->spibrg / hz) > 64) {
> + pm = mpc83xx_spi->spibrg / (hz * 64);
> + if (pm > 16) {
Suppose this didn't happen. So we calculated:
pm = mpc83xx_spi->spibrg / (hz * 64);
And we didn't set any hw flag.
> + cs->hw_mode |= SPMODE_DIV16;
> + pm /= 16;
> + if (pm > 16) {
> + dev_err(&spi->dev, "Requested speed is too "
> + "low: %d Hz. Will use %d Hz instead.\n",
> + hz, mpc83xx_spi->spibrg / 1024);
> + pm = 16;
> + }
> }
> - cs->hw_mode |= SPMODE_PM(pm) | SPMODE_DIV16;
> - } else {
> + } else
> pm = mpc83xx_spi->spibrg / (hz * 4);
Now suppose this did happen. So we calculated:
pm = mpc83xx_spi->spibrg / (hz * 4);
And we didn't set any hw flag either.
So, we used two different formulas with the same hw flags.
Maybe I'm missing something, but this looks quite wrong.
> - if (pm)
> - pm--;
> - cs->hw_mode |= SPMODE_PM(pm);
> - }
> + if (pm)
> + pm--;
> +
> + cs->hw_mode |= SPMODE_PM(pm);
> regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
> if (cs->hw_mode != regval) {
> unsigned long flags;
> --
> 1.5.4
--
Anton Vorontsov
email: [EMAIL PROTECTED]
irc://irc.freenode.net/bd2
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