From: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Stephen Warren <swarren@wwwdotorg.org>,
Peter De Schrijver <pdeschrijver@nvidia.com>,
Prashant Gaikwad <pgaikwad@nvidia.com>,
Mike Turquette <mturquette@linaro.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Paul Walmsley <pwalmsley@nvidia.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 14/16] cpufreq: Add cpufreq driver for Tegra124
Date: Wed, 23 Jul 2014 15:35:46 +0300 [thread overview]
Message-ID: <53CFAC22.40106@nvidia.com> (raw)
In-Reply-To: <20140723070949.GB15759@ulmo.nvidia.com>
On 23/07/14 10:09, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Mon, Jul 21, 2014 at 06:39:00PM +0300, Tuomas Tynkkynen wrote:
> [...]
>> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
> [...]
>> +static int tegra124_cpu_switch_to_dfll(void)
>> +{
>> + struct clk *original_cpu_clk_parent;
>
> Maybe just "parent"?
>
>> + unsigned long rate;
>> + struct dev_pm_opp *opp;
>> + int ret;
>> +
>> + rate = clk_get_rate(cpu_clk);
>> + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
>> + if (IS_ERR(opp))
>> + return PTR_ERR(opp);
>> +
>> + ret = clk_set_rate(dfll_clk, rate);
>> + if (ret)
>> + return ret;
>> +
>> + original_cpu_clk_parent = clk_get_parent(cpu_clk);
>> + clk_set_parent(cpu_clk, pllp_clk);
>> + if (ret)
>> + return ret;
>> +
>> + ret = clk_prepare_enable(dfll_clk);
>> + if (ret)
>> + goto out_switch_to_original_parent;
>
> This could simply be "out" or "err" or anything else shorter than the
> above.
>
>> +
>> + clk_set_parent(cpu_clk, dfll_clk);
>> +
>> + return 0;
>> +
>> +out_switch_to_original_parent:
>> + clk_set_parent(cpu_clk, original_cpu_clk_parent);
>> +
>> + return ret;
>> +}
>> +
>> +static struct platform_device_info cpufreq_cpu0_devinfo = {
>> + .name = "cpufreq-cpu0",
>> +};
>> +
>> +static int tegra124_cpufreq_probe(struct platform_device *pdev)
>> +{
>> + int ret;
>> +
>> + cpu_dev = get_cpu_device(0);
>> + if (!cpu_dev)
>> + return -ENODEV;
>> +
>> + cpu_clk = of_clk_get_by_name(cpu_dev->of_node, "cpu_g");
>> + if (IS_ERR(cpu_clk))
>> + return PTR_ERR(cpu_clk);
>> +
>> + dfll_clk = of_clk_get_by_name(cpu_dev->of_node, "dfll");
>> + if (IS_ERR(dfll_clk)) {
>> + ret = PTR_ERR(dfll_clk);
>> + goto out_put_cpu_clk;
>> + }
>> +
>> + pllx_clk = of_clk_get_by_name(cpu_dev->of_node, "pll_x");
>> + if (IS_ERR(pllx_clk)) {
>> + ret = PTR_ERR(pllx_clk);
>> + goto out_put_dfll_clk;
>> + }
>> +
>> + pllp_clk = of_clk_get_by_name(cpu_dev->of_node, "pll_p");
>> + if (IS_ERR(pllp_clk)) {
>> + ret = PTR_ERR(pllp_clk);
>> + goto out_put_pllx_clk;
>> + }
>
> Can the above not be devm_clk_get(cpu_dev, "...") so that you can remove
> all the clk_put() calls in the cleanup code below?
That would allocate the clks under the cpu_dev's devres list, i.e. all the
clk_puts wouldn't happen when the cpufreq driver goes away, but only when
cpu_dev itself goes away.
>
>> +
>> + ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
>> + if (ret)
>> + goto out_put_pllp_clk;
>> +
>> + ret = tegra124_cpu_switch_to_dfll();
>> + if (ret)
>> + goto out_free_table;
>> +
>> + platform_device_register_full(&cpufreq_cpu0_devinfo);
>
> Should the cpufreq_cpu0_devinfo device perhaps be a child of pdev?
Yeah, I suppose it should.
>> +
>> + return 0;
>> +
>> +out_free_table:
>> + dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
>> +out_put_pllp_clk:
>> + clk_put(pllp_clk);
>> +out_put_pllx_clk:
>> + clk_put(pllx_clk);
>> +out_put_dfll_clk:
>> + clk_put(dfll_clk);
>> +out_put_cpu_clk:
>> + clk_put(cpu_clk);
>> +
>> + return ret;
>> +}
>> +
>> +static struct platform_driver tegra124_cpufreq_platdrv = {
>> + .driver = {
>> + .name = "cpufreq-tegra124",
>> + .owner = THIS_MODULE,
>> + },
>> + .probe = tegra124_cpufreq_probe,
>
> Note that simply leaving out .remove() here doesn't guarantee that the
> driver won't be unloaded. Also building it into the kernel doesn't
> prevent that. You can still unbind the driver via sysfs. So you'd need
> to add a .suppress_bind_attrs = true above.
I hadn't heard about suppress_bind_attrs before, it indeed sounds useful.
> But is there even a reason why we need that? Couldn't we make the
> driver's .remove() undo what .probe() did so that the driver can be
> unloaded?
I guess that could be done, though to fully undo everything the regulator
voltage would also need to be saved/restored.
> Otherwise it probably makes more sense not to use a driver (and dummy
> device) at all as Viresh already mentioned.
>
The dummy platform device is only required for probe deferral, if that
could be solved in a different way then yes.
>> +};
>> +
>> +static const struct of_device_id soc_of_matches[] = {
>> + { .compatible = "nvidia,tegra124", },
>> + {}
>> +};
>> +
>> +static int __init tegra_cpufreq_init(void)
>> +{
>> + int ret;
>> + struct platform_device *pdev;
>> +
>> + if (!of_find_matching_node(NULL, soc_of_matches))
>> + return -ENODEV;
>
> I think this could be of_machine_is_compatible() since there's only a
> single entry in the match table. If there's a good chance that we may
> end up with more entries, perhaps now would be a good time to add an
> of_match_machine() function?
I think this driver should work on Tegra132 without modifications.
of_match_machine() does sound useful for some of the other cpufreq
drivers as well and likely for your soc_is_tegra() from the PMC
series as well.
>
>> +
>> + ret = platform_driver_register(&tegra124_cpufreq_platdrv);
>> + if (ret)
>> + return ret;
>> +
>> + pdev = platform_device_register_simple("cpufreq-tegra124", -1, NULL, 0);
>> + if (IS_ERR(pdev)) {
>> + platform_driver_unregister(&tegra124_cpufreq_platdrv);
>> + return PTR_ERR(pdev);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +MODULE_AUTHOR("Tuomas Tynkkynen <ttynkkynen@nvidia.com>");
>> +MODULE_DESCRIPTION("cpufreq driver for nVIDIA Tegra124");
>
> We use "NVIDIA" everywhere nowadays.
>
>> +MODULE_LICENSE("GPLv2");
>
> The correct license string is "GPL v2".
>
>> +module_init(tegra_cpufreq_init);
>
> The placement of this is unusual. It should go immediately below the
> tegra_cpufreq_init() function.
>
Ok.
Thanks,
Tuomas
--
nvpublic
next prev parent reply other threads:[~2014-07-23 12:35 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-21 15:38 [PATCH v2 00/16] Tegra124 CL-DVFS / DFLL clocksource, plus cpufreq Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 01/16] regmap: Add regmap_get_device Tuomas Tynkkynen
2014-07-25 17:34 ` Mark Brown
2014-07-25 17:43 ` Mark Brown
2014-07-21 15:38 ` [PATCH v2 02/16] regulator: Add helpers for low-level register access Tuomas Tynkkynen
2014-07-25 17:48 ` Mark Brown
2014-07-21 15:38 ` [PATCH v2 03/16] clk: tegra: Add binding for the Tegra124 DFLL clocksource Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 04/16] clk: tegra: Add library for the DFLL clock source (open-loop mode) Tuomas Tynkkynen
2014-08-18 6:05 ` Vince Hsu
2014-07-21 15:38 ` [PATCH v2 05/16] clk: tegra: Add closed loop support for the DFLL Tuomas Tynkkynen
2014-08-18 6:08 ` Vince Hsu
2014-07-21 15:38 ` [PATCH v2 06/16] clk: tegra: Add functions for parsing CVB tables Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 07/16] clk: tegra: Add DFLL DVCO reset control for Tegra124 Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 08/16] clk: tegra: Add Tegra124 DFLL clocksource platform driver Tuomas Tynkkynen
2014-08-12 10:37 ` Vince Hsu
2014-07-21 15:38 ` [PATCH v2 09/16] clk: tegra: Save/restore CCLKG_BURST_POLICY on suspend Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 10/16] clk: tegra: Add the DFLL as a possible parent of the cclk_g clock Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 11/16] ARM: tegra: Add the DFLL to Tegra124 device tree Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 12/16] ARM: tegra: Enable the DFLL on the Jetson TK1 Tuomas Tynkkynen
2014-07-21 15:38 ` [PATCH v2 13/16] cpufreq: tegra124: Add device tree bindings Tuomas Tynkkynen
2014-07-21 15:39 ` [PATCH v2 14/16] cpufreq: Add cpufreq driver for Tegra124 Tuomas Tynkkynen
2014-07-22 0:49 ` Rafael J. Wysocki
2014-07-23 4:44 ` Viresh Kumar
2014-07-23 6:54 ` Thierry Reding
2014-07-23 6:58 ` Viresh Kumar
2014-07-23 7:24 ` Thierry Reding
2014-07-23 8:25 ` Viresh Kumar
2014-07-23 13:51 ` Thierry Reding
2014-07-23 11:57 ` Tuomas Tynkkynen
2014-07-23 16:50 ` Viresh Kumar
2014-07-23 19:17 ` Tuomas Tynkkynen
2014-07-24 0:13 ` Viresh Kumar
2014-07-24 9:10 ` Thierry Reding
2014-07-23 7:09 ` Thierry Reding
2014-07-23 12:35 ` Tuomas Tynkkynen [this message]
2014-07-23 13:59 ` Thierry Reding
2014-07-23 7:21 ` pramod gurav
2014-07-21 15:39 ` [PATCH v2 15/16] ARM: tegra: Add entries for cpufreq on Tegra124 Tuomas Tynkkynen
2014-07-21 15:39 ` [PATCH v2 16/16] ARM: tegra: Update defconfig for tegra124-cpufreq Tuomas Tynkkynen
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