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

Jon Hunter
2018-03-12T10:14:17Z

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.

Cheers
Jon

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nvpublic