diff mbox

[4/8] clk: davinci: add a reset lookup table for psc0

Message ID 20180321120807.18032-5-brgl@bgdev.pl (mailing list archive)
State Superseded, archived
Headers show

Commit Message

Bartosz Golaszewski March 21, 2018, 12:08 p.m. UTC
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(+)

Comments

David Lechner March 21, 2018, 4:01 p.m. UTC | #1
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().

>   	return davinci_psc_register_clocks(dev, da850_psc0_info, 16, base);
>   }
>   
> diff --git a/drivers/clk/davinci/psc.c b/drivers/clk/davinci/psc.c
> index 3b0e59dfbdd7..063df62381ea 100644
> --- a/drivers/clk/davinci/psc.c
> +++ b/drivers/clk/davinci/psc.c
> @@ -425,6 +425,7 @@ __davinci_psc_register_clocks(struct device *dev,
>   
>   	psc->rcdev.ops = &davinci_psc_reset_ops;
>   	psc->rcdev.owner = THIS_MODULE;
> +	psc->rcdev.dev = dev;
>   	psc->rcdev.of_node = dev->of_node;
>   	psc->rcdev.of_reset_n_cells = 1;
>   	psc->rcdev.of_xlate = davinci_psc_reset_of_xlate;
> 

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Bartosz Golaszewski March 21, 2018, 4:08 p.m. UTC | #2
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
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David Lechner March 21, 2018, 4:17 p.m. UTC | #3
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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Bartosz Golaszewski March 23, 2018, 9:07 a.m. UTC | #4
2018-03-21 17:17 GMT+01:00 David Lechner <david@lechnology.com>:
> 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.

On the other hand if clk_get() succeeded, than the psc driver is
already initialized and the subsequent call to reset_control_get()
must succeed. But this is probably too machine-specific for a driver.

Bart
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diff mbox

Patch

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));
 	return davinci_psc_register_clocks(dev, da850_psc0_info, 16, base);
 }
 
diff --git a/drivers/clk/davinci/psc.c b/drivers/clk/davinci/psc.c
index 3b0e59dfbdd7..063df62381ea 100644
--- a/drivers/clk/davinci/psc.c
+++ b/drivers/clk/davinci/psc.c
@@ -425,6 +425,7 @@  __davinci_psc_register_clocks(struct device *dev,
 
 	psc->rcdev.ops = &davinci_psc_reset_ops;
 	psc->rcdev.owner = THIS_MODULE;
+	psc->rcdev.dev = dev;
 	psc->rcdev.of_node = dev->of_node;
 	psc->rcdev.of_reset_n_cells = 1;
 	psc->rcdev.of_xlate = davinci_psc_reset_of_xlate;