Messages in this thread | | | Date | Fri, 28 Jan 2022 16:13:11 +0100 | Subject | Re: [PATCH v7 5/5] rockchip/soc/drivers: Add DTPM description for rk3399 | From | Daniel Lezcano <> |
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Hi Heiko,
thanks for your comments
On 28/01/2022 11:19, Heiko Stübner wrote: > Am Dienstag, 25. Januar 2022, 18:18:09 CET schrieb Daniel Lezcano: >> The DTPM framework does support now the hierarchy description. >> >> The platform specific code can call the hierarchy creation function >> with an array of struct dtpm_node pointing to their parent. >> >> This patch provides a description of the big / Little CPUs and the >> GPU and tie them together under a virtual 'package' name. Only rk3399 is >> described now. >> >> The description could be extended in the future with the memory >> controller with devfreq. >> >> The description is always a module and it describes the soft >> dependencies. The userspace has to load the softdeps module in the >> right order. >> >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
[ ... ]
>> +static struct dtpm_node __initdata rk3399_hierarchy[] = { > > The driver is tristate so buildable as module but uses __initdata. > As it depends on panfrost (which also can be a module) you > probably want a "__initdata_or_module" here .
Well, actually the dependency is wrong.
It should be:
depends on DTPM && m
It will be compiled always as a module.
Referring to the Documentation/kernel-hacking/hacking.rst
"After boot, the kernel frees up a special section; functions marked with ``__init`` and data structures marked with ``__initdata`` are dropped after boot is complete: similarly modules discard this memory after initialization."
So after the module is loaded and the hierarchy is created, nothing will stay in memory (except the future module exit function)
>> + [0]{ .name = "rk3399", >> + .type = DTPM_NODE_VIRTUAL }, >> + [1]{ .name = "package", >> + .type = DTPM_NODE_VIRTUAL, >> + .parent = &rk3399_hierarchy[0] }, >> + [2]{ .name = "/cpus/cpu@0", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [3]{ .name = "/cpus/cpu@1", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [4]{ .name = "/cpus/cpu@2", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [5]{ .name = "/cpus/cpu@3", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [6]{ .name = "/cpus/cpu@100", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [7]{ .name = "/cpus/cpu@101", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [8]{ .name = "/gpu@ff9a0000", >> + .type = DTPM_NODE_DT, >> + .parent = &rk3399_hierarchy[1] }, >> + [9]{ }, > > hmm, do we want a "/* sentinel */" inside the empty last entry? > I think that is pretty common to denote the "this one is the last entry" > of a dynamic list ;-)
Sure
>> +}; >> + >> +static struct of_device_id __initdata rockchip_dtpm_match_table[] = { >> + { .compatible = "rockchip,rk3399", .data = rk3399_hierarchy }, >> + {}, >> +}; >> + >> +static int __init rockchip_dtpm_init(void) >> +{ >> + return dtpm_create_hierarchy(rockchip_dtpm_match_table); >> +} >> +module_init(rockchip_dtpm_init); > > Just for my understanding what happens on driver unload?
ATM it is not possible to unload it.
A second series with the hierarchy destruction will follow once this series is merged. The module unloading will be added here.
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