Re: [PATCH v3 09/11] cpufreq: tegra124-cpufreq: extend to support Tegra210

Peter De Schrijver
2018-03-13T09:28:16Z

On Mon, Mar 12, 2018 at 10:14:17AM +0000, Jon Hunter wrote:
>
> On 09/03/18 08:14, Peter De Schrijver wrote:
> > On Thu, Mar 08, 2018 at 11:25:04PM +0000, Jon Hunter wrote:
> >>
> >> On 06/02/18 16:34, Peter De Schrijver wrote:
> >>> Tegra210 has a very similar CPU clocking scheme than Tegra124. So add
> >>> support in this driver. Also allow for the case where the CPU voltage is
> >>> controlled directly by the DFLL rather than by a separate regulator object.
> >>>
> >>> Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
> >>> ---
> >>> drivers/cpufreq/tegra124-cpufreq.c | 15 ++++++++-------
> >>> 1 file changed, 8 insertions(+), 7 deletions(-)
> >>>
> >>> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
> >>> index 4353025..f8e01a8 100644
> >>> --- a/drivers/cpufreq/tegra124-cpufreq.c
> >>> +++ b/drivers/cpufreq/tegra124-cpufreq.c
> >>> @@ -64,7 +64,8 @@ static void tegra124_cpu_switch_to_pllx(struct tegra124_cpufreq_priv *priv)
> >>> {
> >>> clk_set_parent(priv->cpu_clk, priv->pllp_clk);
> >>> clk_disable_unprepare(priv->dfll_clk);
> >>> - regulator_sync_voltage(priv->vdd_cpu_reg);
> >>> + if (priv->vdd_cpu_reg)
> >>> + regulator_sync_voltage(priv->vdd_cpu_reg);
> >>> clk_set_parent(priv->cpu_clk, priv->pllx_clk);
> >>> }
> >>>
> >>> @@ -89,10 +90,10 @@ static int tegra124_cpufreq_probe(struct platform_device *pdev)
> >>> return -ENODEV;
> >>>
> >>> priv->vdd_cpu_reg = regulator_get(cpu_dev, "vdd-cpu");
> >>> - if (IS_ERR(priv->vdd_cpu_reg)) {
> >>> - ret = PTR_ERR(priv->vdd_cpu_reg);
> >>> - goto out_put_np;
> >>> - }
> >>> + if (IS_ERR(priv->vdd_cpu_reg) != -EPROBE_DEFER)
> >>> + priv->vdd_cpu_reg = NULL;
> >>> + else
> >>> + return -EPROBE_DEFER;
> >>
> >> I am still not sure that we should rely on the fact that the regulator
> >> is not present in DT to imply that we do not need it. I think that we
> >> should be checking if we are using I2C mode here.
> >>
> >
> > The cpufreq driver doesn't know this however. Also the current approach of
> > setting the same voltage when switching to pll_x is incorrect. The CVB
> > tables when using pll_x include more margin than when using the DFLL.
>
> Ah yes I see now. However, we are going to need to update the DT doc,
> because 'vdd-cpu-supply' is listed as required.
>

Ok.

Peter.