diff mbox

[v2,06/14] mmc: dw_mmc: simplify optional reset handling

Message ID 1490005679.2917.32.camel@pengutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Philipp Zabel March 20, 2017, 10:27 a.m. UTC
Hi Andrzej,

On Mon, 2017-03-20 at 11:03 +0100, Andrzej Hajda wrote:
> Hi Philipp,
> 
> On 20.03.2017 10:53, Philipp Zabel wrote:
> > On Mon, 2017-03-20 at 10:22 +0100, Andrzej Hajda wrote:
> >> Hi Philipp,
> >>
> >> Todays next branch does not work with exynos5433-tm2 board.
> >> I guess this patch causes regression. On MMC without reset controller I
> >> get errors:
> >> [    4.938222] dwmmc_exynos 15540000.mshc: platform data not available
> >> [    4.943268] dwmmc_exynos: probe of 15540000.mshc failed with error -22

I was thrown off by this. Should maybe dw_mci_probe return the error
value reported by dw_mci_parse_dt instead of always returning -EINVAL?

> >> [    4.950184] dwmmc_exynos 15560000.mshc: platform data not available
> >> [    4.955962] dwmmc_exynos: probe of 15560000.mshc failed with error -22
> >>
> >> Commenting out reset controller get and error checks 'fixes' the issue.
> >>
> >> On 15.03.2017 12:31, Philipp Zabel wrote:
> >>> As of commit bb475230b8e5 ("reset: make optional functions really
> >>> optional"), the reset framework API calls use NULL pointers to describe
> >>> optional, non-present reset controls.
> >>>
> >>> This allows to return errors from devm_reset_control_get_optional and to
> >>> call reset_control_(de)assert unconditionally.
> >>>
> >>> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> >>> ---
> >>>  drivers/mmc/host/dw_mmc.c | 14 +++++---------
> >>>  1 file changed, 5 insertions(+), 9 deletions(-)
> >>>
> >>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> >>> index a9ac0b4573131..3d62b0a1f81cb 100644
> >>> --- a/drivers/mmc/host/dw_mmc.c
> >>> +++ b/drivers/mmc/host/dw_mmc.c
> >>> @@ -2968,10 +2968,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
> >>>  
> >>>  	/* find reset controller when exist */
> >>>  	pdata->rstc = devm_reset_control_get_optional(dev, "reset");
> >>> -	if (IS_ERR(pdata->rstc)) {
> >>> -		if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER)
> >>> -			return ERR_PTR(-EPROBE_DEFER);
> >>> -	}
> >>> +	if (IS_ERR(pdata->rstc))
> >>> +		return ERR_CAST(pdata->rstc);
> >>
> >> With three lines above commented out it works.
> > So devm_reset_control_get_optional returns -EINVAL. Why?
> >
> > The mshc@15560000 node is compatible to "samsung,exynos7-dw-mshc-smu",
> > so that's dw_mmc-exynos.c calling dw_mci_pltfm_register, which then
> > calls dw_mci_probe, passing the original platform device as
> > host->dev = &pdev->dev, and I expect __of_reset_control_get being called
> > with a valid DT node (dev->of_node).
> > Since id is set to "reset", of_property_match_string(node,
> > "reset-names", id) should then be called and return -EINVAL because the
> > "reset-names" property does not exist. Then __of_reset_control_get
> > should return NULL because optional == true.
> > Some of this obviously doesn't happen, where am I wrong?
> 
> 
> When RESET_CONTROLLER is not enabled dummy stubs return -ENOSUPP error [1].
> 
> [1]: http://lxr.free-electrons.com/source/include/linux/reset.h#L77

Thanks, I suppose that issue should be fixed by:

----------8<----------
---------->8----------

regards
Philipp

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Comments

Andrzej Hajda March 20, 2017, 10:49 a.m. UTC | #1
On 20.03.2017 11:27, Philipp Zabel wrote:
> Hi Andrzej,
>
> On Mon, 2017-03-20 at 11:03 +0100, Andrzej Hajda wrote:
>> Hi Philipp,
>>
>> On 20.03.2017 10:53, Philipp Zabel wrote:
>>> On Mon, 2017-03-20 at 10:22 +0100, Andrzej Hajda wrote:
>>>> Hi Philipp,
>>>>
>>>> Todays next branch does not work with exynos5433-tm2 board.
>>>> I guess this patch causes regression. On MMC without reset controller I
>>>> get errors:
>>>> [    4.938222] dwmmc_exynos 15540000.mshc: platform data not available
>>>> [    4.943268] dwmmc_exynos: probe of 15540000.mshc failed with error -22
> I was thrown off by this. Should maybe dw_mci_probe return the error
> value reported by dw_mci_parse_dt instead of always returning -EINVAL?
>
>>>> [    4.950184] dwmmc_exynos 15560000.mshc: platform data not available
>>>> [    4.955962] dwmmc_exynos: probe of 15560000.mshc failed with error -22
>>>>
>>>> Commenting out reset controller get and error checks 'fixes' the issue.
>>>>
>>>> On 15.03.2017 12:31, Philipp Zabel wrote:
>>>>> As of commit bb475230b8e5 ("reset: make optional functions really
>>>>> optional"), the reset framework API calls use NULL pointers to describe
>>>>> optional, non-present reset controls.
>>>>>
>>>>> This allows to return errors from devm_reset_control_get_optional and to
>>>>> call reset_control_(de)assert unconditionally.
>>>>>
>>>>> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
>>>>> ---
>>>>>  drivers/mmc/host/dw_mmc.c | 14 +++++---------
>>>>>  1 file changed, 5 insertions(+), 9 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>>>> index a9ac0b4573131..3d62b0a1f81cb 100644
>>>>> --- a/drivers/mmc/host/dw_mmc.c
>>>>> +++ b/drivers/mmc/host/dw_mmc.c
>>>>> @@ -2968,10 +2968,8 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>>>>>  
>>>>>  	/* find reset controller when exist */
>>>>>  	pdata->rstc = devm_reset_control_get_optional(dev, "reset");
>>>>> -	if (IS_ERR(pdata->rstc)) {
>>>>> -		if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER)
>>>>> -			return ERR_PTR(-EPROBE_DEFER);
>>>>> -	}
>>>>> +	if (IS_ERR(pdata->rstc))
>>>>> +		return ERR_CAST(pdata->rstc);
>>>> With three lines above commented out it works.
>>> So devm_reset_control_get_optional returns -EINVAL. Why?
>>>
>>> The mshc@15560000 node is compatible to "samsung,exynos7-dw-mshc-smu",
>>> so that's dw_mmc-exynos.c calling dw_mci_pltfm_register, which then
>>> calls dw_mci_probe, passing the original platform device as
>>> host->dev = &pdev->dev, and I expect __of_reset_control_get being called
>>> with a valid DT node (dev->of_node).
>>> Since id is set to "reset", of_property_match_string(node,
>>> "reset-names", id) should then be called and return -EINVAL because the
>>> "reset-names" property does not exist. Then __of_reset_control_get
>>> should return NULL because optional == true.
>>> Some of this obviously doesn't happen, where am I wrong?
>>
>> When RESET_CONTROLLER is not enabled dummy stubs return -ENOSUPP error [1].
>>
>> [1]: http://lxr.free-electrons.com/source/include/linux/reset.h#L77
> Thanks, I suppose that issue should be fixed by:
>
> ----------8<----------
> diff --git a/include/linux/reset.h b/include/linux/reset.h
> index 86b4ed75359e8..c905ff1c21ec6 100644
> --- a/include/linux/reset.h
> +++ b/include/linux/reset.h
> @@ -74,14 +74,14 @@ static inline struct reset_control *__of_reset_control_get(
>  					const char *id, int index, bool shared,
>  					bool optional)
>  {
> -	return ERR_PTR(-ENOTSUPP);
> +	return optional ? NULL : ERR_PTR(-ENOTSUPP);
>  }
>  
>  static inline struct reset_control *__devm_reset_control_get(
>  					struct device *dev, const char *id,
>  					int index, bool shared, bool optional)
>  {
> -	return ERR_PTR(-ENOTSUPP);
> +	return optional ? NULL : ERR_PTR(-ENOTSUPP);
>  }
>  
>  #endif /* CONFIG_RESET_CONTROLLER */
> ---------->8----------

In dw_mmc.c file there are also unconditional calls to
reset_control_assert, with disabled RESET_CONTROLLER it will cause
unexpected WARNs.
Anyway if you change reset API as above I think you should remove all
warns from reset stubs, because NULL reset is valid, but these warns are
there for reason - contradiction.

Regards
Andrzej

>
> regards
> Philipp
>
>
>
>

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Philipp Zabel March 20, 2017, 11 a.m. UTC | #2
On Mon, 2017-03-20 at 11:49 +0100, Andrzej Hajda wrote:
> On 20.03.2017 11:27, Philipp Zabel wrote:
[...]
> > diff --git a/include/linux/reset.h b/include/linux/reset.h
> > index 86b4ed75359e8..c905ff1c21ec6 100644
> > --- a/include/linux/reset.h
> > +++ b/include/linux/reset.h
> > @@ -74,14 +74,14 @@ static inline struct reset_control *__of_reset_control_get(
> >  					const char *id, int index, bool shared,
> >  					bool optional)
> >  {
> > -	return ERR_PTR(-ENOTSUPP);
> > +	return optional ? NULL : ERR_PTR(-ENOTSUPP);
> >  }
> >  
> >  static inline struct reset_control *__devm_reset_control_get(
> >  					struct device *dev, const char *id,
> >  					int index, bool shared, bool optional)
> >  {
> > -	return ERR_PTR(-ENOTSUPP);
> > +	return optional ? NULL : ERR_PTR(-ENOTSUPP);
> >  }
> >  
> >  #endif /* CONFIG_RESET_CONTROLLER */
> > ---------->8----------
> 
> In dw_mmc.c file there are also unconditional calls to
> reset_control_assert, with disabled RESET_CONTROLLER it will cause
> unexpected WARNs.
> Anyway if you change reset API as above I think you should remove all
> warns from reset stubs, because NULL reset is valid, but these warns are
> there for reason - contradiction.

You are right, I have to let go of those, too.

regards
Philipp

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Ulf Hansson March 20, 2017, 6:09 p.m. UTC | #3
On 20 March 2017 at 12:00, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> On Mon, 2017-03-20 at 11:49 +0100, Andrzej Hajda wrote:
>> On 20.03.2017 11:27, Philipp Zabel wrote:
> [...]
>> > diff --git a/include/linux/reset.h b/include/linux/reset.h
>> > index 86b4ed75359e8..c905ff1c21ec6 100644
>> > --- a/include/linux/reset.h
>> > +++ b/include/linux/reset.h
>> > @@ -74,14 +74,14 @@ static inline struct reset_control *__of_reset_control_get(
>> >                                     const char *id, int index, bool shared,
>> >                                     bool optional)
>> >  {
>> > -   return ERR_PTR(-ENOTSUPP);
>> > +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>> >  }
>> >
>> >  static inline struct reset_control *__devm_reset_control_get(
>> >                                     struct device *dev, const char *id,
>> >                                     int index, bool shared, bool optional)
>> >  {
>> > -   return ERR_PTR(-ENOTSUPP);
>> > +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>> >  }
>> >
>> >  #endif /* CONFIG_RESET_CONTROLLER */
>> > ---------->8----------
>>
>> In dw_mmc.c file there are also unconditional calls to
>> reset_control_assert, with disabled RESET_CONTROLLER it will cause
>> unexpected WARNs.
>> Anyway if you change reset API as above I think you should remove all
>> warns from reset stubs, because NULL reset is valid, but these warns are
>> there for reason - contradiction.
>
> You are right, I have to let go of those, too.
>
> regards
> Philipp
>
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Ulf Hansson March 20, 2017, 6:10 p.m. UTC | #4
On 20 March 2017 at 12:00, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> On Mon, 2017-03-20 at 11:49 +0100, Andrzej Hajda wrote:
>> On 20.03.2017 11:27, Philipp Zabel wrote:
> [...]
>> > diff --git a/include/linux/reset.h b/include/linux/reset.h
>> > index 86b4ed75359e8..c905ff1c21ec6 100644
>> > --- a/include/linux/reset.h
>> > +++ b/include/linux/reset.h
>> > @@ -74,14 +74,14 @@ static inline struct reset_control *__of_reset_control_get(
>> >                                     const char *id, int index, bool shared,
>> >                                     bool optional)
>> >  {
>> > -   return ERR_PTR(-ENOTSUPP);
>> > +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>> >  }
>> >
>> >  static inline struct reset_control *__devm_reset_control_get(
>> >                                     struct device *dev, const char *id,
>> >                                     int index, bool shared, bool optional)
>> >  {
>> > -   return ERR_PTR(-ENOTSUPP);
>> > +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>> >  }
>> >
>> >  #endif /* CONFIG_RESET_CONTROLLER */
>> > ---------->8----------
>>
>> In dw_mmc.c file there are also unconditional calls to
>> reset_control_assert, with disabled RESET_CONTROLLER it will cause
>> unexpected WARNs.
>> Anyway if you change reset API as above I think you should remove all
>> warns from reset stubs, because NULL reset is valid, but these warns are
>> there for reason - contradiction.
>
> You are right, I have to let go of those, too.


Until fixed, I have dropped the three changes from my next branch
related to this. Please re-post when fixed.

Kind regards
Uffe

>
> regards
> Philipp
>
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Jaehoon Chung March 21, 2017, 12:12 p.m. UTC | #5
Hi All,

On 03/21/2017 03:10 AM, Ulf Hansson wrote:
> On 20 March 2017 at 12:00, Philipp Zabel <p.zabel@pengutronix.de> wrote:
>> On Mon, 2017-03-20 at 11:49 +0100, Andrzej Hajda wrote:
>>> On 20.03.2017 11:27, Philipp Zabel wrote:
>> [...]
>>>> diff --git a/include/linux/reset.h b/include/linux/reset.h
>>>> index 86b4ed75359e8..c905ff1c21ec6 100644
>>>> --- a/include/linux/reset.h
>>>> +++ b/include/linux/reset.h
>>>> @@ -74,14 +74,14 @@ static inline struct reset_control *__of_reset_control_get(
>>>>                                     const char *id, int index, bool shared,
>>>>                                     bool optional)
>>>>  {
>>>> -   return ERR_PTR(-ENOTSUPP);
>>>> +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>>>>  }
>>>>
>>>>  static inline struct reset_control *__devm_reset_control_get(
>>>>                                     struct device *dev, const char *id,
>>>>                                     int index, bool shared, bool optional)
>>>>  {
>>>> -   return ERR_PTR(-ENOTSUPP);
>>>> +   return optional ? NULL : ERR_PTR(-ENOTSUPP);
>>>>  }
>>>>
>>>>  #endif /* CONFIG_RESET_CONTROLLER */
>>>> ---------->8----------
>>>
>>> In dw_mmc.c file there are also unconditional calls to
>>> reset_control_assert, with disabled RESET_CONTROLLER it will cause
>>> unexpected WARNs.
>>> Anyway if you change reset API as above I think you should remove all
>>> warns from reset stubs, because NULL reset is valid, but these warns are
>>> there for reason - contradiction.
>>
>> You are right, I have to let go of those, too.
> 
> 
> Until fixed, I have dropped the three changes from my next branch
> related to this. Please re-post when fixed.

I missed this patch. If resend the patch, i will check.

Best Regards,
Jaehoon Chung

> 
> Kind regards
> Uffe
> 
>>
>> regards
>> Philipp
>>
> 
> 
> 

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diff mbox

Patch

diff --git a/include/linux/reset.h b/include/linux/reset.h
index 86b4ed75359e8..c905ff1c21ec6 100644
--- a/include/linux/reset.h
+++ b/include/linux/reset.h
@@ -74,14 +74,14 @@  static inline struct reset_control *__of_reset_control_get(
 					const char *id, int index, bool shared,
 					bool optional)
 {
-	return ERR_PTR(-ENOTSUPP);
+	return optional ? NULL : ERR_PTR(-ENOTSUPP);
 }
 
 static inline struct reset_control *__devm_reset_control_get(
 					struct device *dev, const char *id,
 					int index, bool shared, bool optional)
 {
-	return ERR_PTR(-ENOTSUPP);
+	return optional ? NULL : ERR_PTR(-ENOTSUPP);
 }
 
 #endif /* CONFIG_RESET_CONTROLLER */