On 12/10/2013 01:32 AM, Stephen Warren wrote:
On 12/09/2013 01:44 AM, bilhuang wrote:
On 12/06/2013 07:04 AM, Stephen Warren wrote:
On 12/05/2013 12:44 AM, Bill Huang wrote:
Re-model Tegra cpufreq driver to support all Tegra series of SoCs.
* Make tegra-cpufreq.c a generic Tegra cpufreq driver.
* Move Tegra20 specific codes into tegra20-cpufreq.c.
* Bind Tegra cpufreq dirver with a fake device so defer probe would work
when we're going to get regulator in the driver to support voltage
scaling (DVFS).
diff --git a/drivers/cpufreq/tegra-cpufreq.c
b/drivers/cpufreq/tegra-cpufreq.c
@@ -91,14 +40,10 @@ static int tegra_update_cpu_speed(struct
cpufreq_policy *policy,
...
+ if (soc_config->vote_emc_on_cpu_rate)
+ soc_config->vote_emc_on_cpu_rate(rate);
+
+ ret = soc_config->cpu_clk_set_rate(rate * 1000);
if (ret)
pr_err("cpu-tegra: Failed to set cpu frequency to %lu kHz\n",
rate);
Is there any/much shared code left in this file after this patch? It
seems like all this file does now is make each cpufreq callback function
call soc_config->the_same_function_name(). If so, wouldn't it be better
to simply implement completely separate tegar20-cpufreq and
tegra30-cpufreq drivers, and register them each directly with the
cpufreq core, to avoid this file doing all the indirection?
I think this file is needed since we can shared the registration and
probe logic for different SoCs.
But there's basically nothing in probe() already, and if we have a
separate driver for each SoC, then there's even less code; just a call
to devm_kzalloc() for the device-specific data (which will be
SoC-specific in size anyway), and a call to cpufreq_register_driver(). I
don't think it's worth sharing that if it means that every other
function needs to be an indirect function call.
OK that makes sense.
-int __init tegra_cpufreq_init(void)
+static struct {
+ char *compat;
+ int (*init)(struct tegra_cpufreq_data *,
+ const struct tegra_cpufreq_config **);
+} tegra_init_funcs[] = {
+ { "nvidia,tegra20", tegra20_cpufreq_init },
+};
+
+static int tegra_cpufreq_probe(struct platform_device *pdev)
...
+ for (i = 0; i < ARRAY_SIZE(tegra_init_funcs); i++) {
+ if (of_machine_is_compatible(tegra_init_funcs[i].compat)) {
+ ret = tegra_init_funcs[i].init(tegra_data, &soc_config);
+ if (!ret)
+ break;
+ else
+ goto out;
+ }
}
+ if (i == ARRAY_SIZE(tegra_init_funcs))
+ goto out;
I think there are better ways of doing this than open-coding it. Perhaps
of_match_device() or the platform-driver equivalent could be made to
work?
Open coding is everywhere in OF helper functions actually. I doubt if we
can use of_match_device() if we're not adding node in DT.
If we're matching the platform device then we might need open coding, no?
For platform devices, you can set up the id_table of struct
platform_driver, and then simply call platform_get_device_id(pdev)
inside probe() to find the matching entry. drivers/i2c/busses/i2c-at91.c
is an example of how this works (just some random driver I found using
grep).
If we're going to have separate driver for each SoC, then we don't need
platform_get_device_id(pdev) stuffs...
What I would like to do is creating platform cpufreq device with name
"${root_compatible}-cpufreq" then each SoC cpufreq driver can bind to
it, but the question is, which file is the best place to do this? Create
a new file for this or use existing file like arch/arm/mach-tegra/tegra.c?
+int __init tegra_cpufreq_init(void)
+{
+ struct platform_device_info devinfo = { .name = "tegra-cpufreq", };
+
+ platform_device_register_full(&devinfo);
+
+ return 0;
}
EXPORT_SYMBOL(tegra_cpufreq_init);
Perhaps instead of hard-coding the name "tegra-cpufreq" here, you could
dynamically construct the device name based on the DT's root compatible
value, register "${root_compatible}-cpufreq", e.g.
"nvidia,tegra20-cpufreq" or "nvidia,tegra30-cpufreq". That would allow
the kernel's standard device/driver matching mechanism to pick the
correct driver to instantiate. Perhaps you could even dynamically
register an OF device so that you can use of_match_device() in probe, if
I guess what you meant dynamically register an OF device is registering
an fake OF device by calling of_device_add(), no? If yes then what
of_node should we give?
Yes. Good question about which node. I guess the root node would be the
only one that made any sense at all, and admittedly it doesn't make a
huge amount of sense. Perhaps registers a platform device rather than an
OF device would make more sense. See platform_device_register() I think.
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