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SubjectRe: [PATCH 4/8] clk: davinci: add a reset lookup table for psc0
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On 03/21/2018 11:08 AM, Bartosz Golaszewski wrote:
> 2018-03-21 17:01 GMT+01:00 David Lechner <david@lechnology.com>:
>> On 03/21/2018 07:08 AM, Bartosz Golaszewski wrote:
>>>
>>> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>>>
>>> In order to be able to use the reset framework in legacy boot mode as
>>> well, add the reset lookup table to the psc driver for da850 variant.
>>>
>>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>>> ---
>>> drivers/clk/davinci/psc-da850.c | 8 ++++++++
>>> drivers/clk/davinci/psc.c | 1 +
>>> 2 files changed, 9 insertions(+)
>>>
>>> diff --git a/drivers/clk/davinci/psc-da850.c
>>> b/drivers/clk/davinci/psc-da850.c
>>> index ccc7eb17bf3a..395db4b2c0ee 100644
>>> --- a/drivers/clk/davinci/psc-da850.c
>>> +++ b/drivers/clk/davinci/psc-da850.c
>>> @@ -6,6 +6,7 @@
>>> */
>>> #include <linux/clk-provider.h>
>>> +#include <linux/reset-controller.h>
>>> #include <linux/clk.h>
>>> #include <linux/clkdev.h>
>>> #include <linux/init.h>
>>> @@ -66,8 +67,15 @@ LPSC_CLKDEV3(ecap_clkdev, "fck", "ecap.0",
>>> "fck", "ecap.1",
>>> "fck", "ecap.2");
>>> +static struct reset_control_lookup da850_psc0_reset_lookup_table[] = {
>>> + RESET_LOOKUP("davinci-rproc.0", NULL, 15),
>>> +};
>>> +
>>> static int da850_psc0_init(struct device *dev, void __iomem *base)
>>> {
>>> + reset_controller_add_lookup("da850-psc0",
>>> + da850_psc0_reset_lookup_table,
>>> +
>>> ARRAY_SIZE(da850_psc0_reset_lookup_table));
>>
>>
>> Could there be a race condition here since you are adding the lookup
>> *before*
>> you are adding the actual provider? It seems like
>> reset_controller_add_lookup()
>> should be after davinci_psc_register_clocks().
>>
>
> I don't think so, because reset_controller_add_lookup() only adds the
> lookup structure to the list in reset/core.c. The actual reset
> controller struct is only located and used when reset_control_get_*()
> is called, so after probing the user. And it's all protected with
> mutexes.
>
> This made me think though - maybe if we can't locate the controller,
> we should return -EPROBE_DEFER from probe in davinci-rproc?
>
> Bart
>

Yes, especially since we know that the PSC driver itself does get
deferred already.

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