On Thu, Apr 30, 2015 at 07:45:54PM +0200, Sebastian Hesselbarth wrote:
> When changing PLL rate significantly, PLLs have to be reset. Add a function
> to perform and check for successful PLL reset.
>
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> ---
> Cc: Mike Turquette <mturquette@xxxxxxxxxx>
> Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> Cc: Jean-Francois Moine <moinejf@xxxxxxx>
> Cc: Michael Welling <mwelling@xxxxxxxx>
> Cc: Russell King <rmk+linux@xxxxxxxxxxxxxxxx>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Cc: linux-clk@xxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
> drivers/clk/clk-si5351.c | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
> index beeb57bbb04c..9b97c134e3c1 100644
> --- a/drivers/clk/clk-si5351.c
> +++ b/drivers/clk/clk-si5351.c
> @@ -366,6 +366,32 @@ static const struct clk_ops si5351_vxco_ops = {
> * = (MSNx_P1*MSNx_P3 + MSNx_P2 + 512*MSNx_P3)/(128*MSNx_P3)
> *
> */
> +static int si5351_pll_reset(struct si5351_hw_data *hwdata)
> +{
> + unsigned long timeout;
> + u8 mask = (hwdata->num == 0) ?
> + SI5351_STATUS_LOL_A : SI5351_STATUS_LOL_B;
> +
> + si5351_reg_write(hwdata->drvdata, SI5351_PLL_RESET,
> + (hwdata->num == 0) ? SI5351_PLL_RESET_A :
> + SI5351_PLL_RESET_B);
> + timeout = jiffies + msecs_to_jiffies(100);
> + do {
> + if ((si5351_reg_read(hwdata->drvdata, SI5351_DEVICE_STATUS) &
> + mask) == 0)
> + break;
> + if (time_after(jiffies, timeout)) {
> + dev_err(&hwdata->drvdata->client->dev,
> + "timeout waiting for pll %d reset\n",
> + hwdata->num);
> + return -EBUSY;
> + };
> + udelay(250);
> + } while (true);
> +
> + return 0;
> +}
> +
> static int _si5351_pll_reparent(struct si5351_driver_data *drvdata,
> int num, enum si5351_pll_src parent)
> {
> @@ -519,6 +545,9 @@ static int si5351_pll_set_rate(struct clk_hw *hw, unsigned long rate,
> SI5351_CLK_INTEGER_MODE,
> (hwdata->params.p2 == 0) ? SI5351_CLK_INTEGER_MODE : 0);
>
> + /* reset pll after rate change */
> + si5351_pll_reset(hwdata);
> +
What is the point of having a return code if it is not being used?
> dev_dbg(&hwdata->drvdata->client->dev,
> "%s - %s: p1 = %lu, p2 = %lu, p3 = %lu, parent_rate = %lu, rate = %lu\n",
> __func__, __clk_get_name(hwdata->hw.clk),
> --
> 2.1.0
>
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