[PATCH] mfd: omap-usb-tll: check clk_prepare return code

[PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Karol Przybylski]

clk_prepare() is called in usbtll_omap_probe to fill clk array.
Return code is not checked, leaving possible error condition unhandled.

Added variable to hold return value from clk_prepare() and dev_dbg statement
when it's not successful.

Found in coverity scan, CID 1594680

Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
---
 drivers/mfd/omap-usb-tll.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
index 0f7fdb99c809..2e9319ee1b74 100644
--- a/drivers/mfd/omap-usb-tll.c
+++ b/drivers/mfd/omap-usb-tll.c
@@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
 	struct device				*dev =  &pdev->dev;
 	struct usbtll_omap			*tll;
 	void __iomem				*base;
-	int					i, nch, ver;
+	int					i, nch, ver, err;
 
 	dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
 
@@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
 					"usb_tll_hs_usb_ch%d_clk", i);
 		tll->ch_clk[i] = clk_get(dev, clkname);
 
-		if (IS_ERR(tll->ch_clk[i]))
+		if (IS_ERR(tll->ch_clk[i])) {
 			dev_dbg(dev, "can't get clock : %s\n", clkname);
-		else
-			clk_prepare(tll->ch_clk[i]);
+		} else {
+			err = clk_prepare(tll->ch_clk[i]);
+			if (err)
+				dev_dbg(dev, "clock prepare error for: %s\n", clkname);
+		}
 	}
 
 	pm_runtime_put_sync(dev);
-- 
2.34.1

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Roger Quadros]

Hi,

On 13/11/2024 23:16, Karol Przybylski wrote:
> clk_prepare() is called in usbtll_omap_probe to fill clk array.
> Return code is not checked, leaving possible error condition unhandled.
> 
> Added variable to hold return value from clk_prepare() and dev_dbg statement
> when it's not successful.
> 
> Found in coverity scan, CID 1594680
> 
> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> ---
>  drivers/mfd/omap-usb-tll.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> index 0f7fdb99c809..2e9319ee1b74 100644
> --- a/drivers/mfd/omap-usb-tll.c
> +++ b/drivers/mfd/omap-usb-tll.c
> @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
>  	struct device				*dev =  &pdev->dev;
>  	struct usbtll_omap			*tll;
>  	void __iomem				*base;
> -	int					i, nch, ver;
> +	int					i, nch, ver, err;
>  
>  	dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
>  
> @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
>  					"usb_tll_hs_usb_ch%d_clk", i);
>  		tll->ch_clk[i] = clk_get(dev, clkname);
>  
> -		if (IS_ERR(tll->ch_clk[i]))
> +		if (IS_ERR(tll->ch_clk[i])) {
>  			dev_dbg(dev, "can't get clock : %s\n", clkname);
> -		else
> -			clk_prepare(tll->ch_clk[i]);
> +		} else {
> +			err = clk_prepare(tll->ch_clk[i]);
> +			if (err)
> +				dev_dbg(dev, "clock prepare error for: %s\n", clkname);

dev_err()?

I think we should return the error in this case.
(after unpreparing the prepared clocks and clk_put())

> +		}
>  	}
>  
>  	pm_runtime_put_sync(dev);

-- 
cheers,
-roger

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Andreas Kemnade]

Am Tue, 19 Nov 2024 15:10:23 +0200
schrieb Roger Quadros <rogerq@kernel.org>:

> Hi,
> 
> On 13/11/2024 23:16, Karol Przybylski wrote:
> > clk_prepare() is called in usbtll_omap_probe to fill clk array.
> > Return code is not checked, leaving possible error condition unhandled.
> > 
> > Added variable to hold return value from clk_prepare() and dev_dbg statement
> > when it's not successful.
> > 
> > Found in coverity scan, CID 1594680
> > 
> > Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> > ---
> >  drivers/mfd/omap-usb-tll.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> > index 0f7fdb99c809..2e9319ee1b74 100644
> > --- a/drivers/mfd/omap-usb-tll.c
> > +++ b/drivers/mfd/omap-usb-tll.c
> > @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >  	struct device				*dev =  &pdev->dev;
> >  	struct usbtll_omap			*tll;
> >  	void __iomem				*base;
> > -	int					i, nch, ver;
> > +	int					i, nch, ver, err;
> >  
> >  	dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
> >  
> > @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >  					"usb_tll_hs_usb_ch%d_clk", i);
> >  		tll->ch_clk[i] = clk_get(dev, clkname);
> >  
> > -		if (IS_ERR(tll->ch_clk[i]))
> > +		if (IS_ERR(tll->ch_clk[i])) {
> >  			dev_dbg(dev, "can't get clock : %s\n", clkname);

if you want dev_err() later, then why not here?

> > -		else
> > -			clk_prepare(tll->ch_clk[i]);
> > +		} else {
> > +			err = clk_prepare(tll->ch_clk[i]);
> > +			if (err)
> > +				dev_dbg(dev, "clock prepare error for: %s\n", clkname);  
> 
> dev_err()?
> 
So why do you want a different return handling here? (I doubt there is
any clock having a real prepare() involved here)

As said in an earlier incarnation of this patch, the real question is
whether having partial clocks available is a valid operating scenario.
If yes, then the error should be ignored. If no, then bailing out early
is a good idea.

clk_prepare() errors are catched by failing clk_enable() later,
ch_clk[i] is checked later, too.

> I think we should return the error in this case.
> (after unpreparing the prepared clocks and clk_put())
>
and pm_runtime_put_sync(dev) 

Regards,
Andreas

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Roger Quadros]

On 19/11/2024 15:56, Andreas Kemnade wrote:
> Am Tue, 19 Nov 2024 15:10:23 +0200
> schrieb Roger Quadros <rogerq@kernel.org>:
> 
>> Hi,
>>
>> On 13/11/2024 23:16, Karol Przybylski wrote:
>>> clk_prepare() is called in usbtll_omap_probe to fill clk array.
>>> Return code is not checked, leaving possible error condition unhandled.
>>>
>>> Added variable to hold return value from clk_prepare() and dev_dbg statement
>>> when it's not successful.
>>>
>>> Found in coverity scan, CID 1594680
>>>
>>> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
>>> ---
>>>  drivers/mfd/omap-usb-tll.c | 11 +++++++----
>>>  1 file changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
>>> index 0f7fdb99c809..2e9319ee1b74 100644
>>> --- a/drivers/mfd/omap-usb-tll.c
>>> +++ b/drivers/mfd/omap-usb-tll.c
>>> @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
>>>  	struct device				*dev =  &pdev->dev;
>>>  	struct usbtll_omap			*tll;
>>>  	void __iomem				*base;
>>> -	int					i, nch, ver;
>>> +	int					i, nch, ver, err;
>>>  
>>>  	dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
>>>  
>>> @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
>>>  					"usb_tll_hs_usb_ch%d_clk", i);
>>>  		tll->ch_clk[i] = clk_get(dev, clkname);
>>>  
>>> -		if (IS_ERR(tll->ch_clk[i]))
>>> +		if (IS_ERR(tll->ch_clk[i])) {
>>>  			dev_dbg(dev, "can't get clock : %s\n", clkname);
> 
> if you want dev_err() later, then why not here?

Because clk is optional. If it is not there then we should not complain.
But if it is there then it needs to be enabled successfully.

> 
>>> -		else
>>> -			clk_prepare(tll->ch_clk[i]);
>>> +		} else {
>>> +			err = clk_prepare(tll->ch_clk[i]);
>>> +			if (err)
>>> +				dev_dbg(dev, "clock prepare error for: %s\n", clkname);  
>>
>> dev_err()?
>>
> So why do you want a different return handling here? (I doubt there is
> any clock having a real prepare() involved here)
> 
> As said in an earlier incarnation of this patch, the real question is
> whether having partial clocks available is a valid operating scenario.
> If yes, then the error should be ignored. If no, then bailing out early
> is a good idea.

In the DT binding, clocks is optional. So if it doesn't exist it is not
an error condition.

> 
> clk_prepare() errors are catched by failing clk_enable() later,
> ch_clk[i] is checked later, too.
> 
>> I think we should return the error in this case.
>> (after unpreparing the prepared clocks and clk_put())
>>
> and pm_runtime_put_sync(dev) 
> 
> Regards,
> Andreas

-- 
cheers,
-roger

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Andreas Kemnade]

Am Tue, 19 Nov 2024 16:16:42 +0200
schrieb Roger Quadros <rogerq@kernel.org>:

> On 19/11/2024 15:56, Andreas Kemnade wrote:
> > Am Tue, 19 Nov 2024 15:10:23 +0200
> > schrieb Roger Quadros <rogerq@kernel.org>:
> >   
> >> Hi,
> >>
> >> On 13/11/2024 23:16, Karol Przybylski wrote:  
> >>> clk_prepare() is called in usbtll_omap_probe to fill clk array.
> >>> Return code is not checked, leaving possible error condition unhandled.
> >>>
> >>> Added variable to hold return value from clk_prepare() and dev_dbg statement
> >>> when it's not successful.
> >>>
> >>> Found in coverity scan, CID 1594680
> >>>
> >>> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> >>> ---
> >>>  drivers/mfd/omap-usb-tll.c | 11 +++++++----
> >>>  1 file changed, 7 insertions(+), 4 deletions(-)
> >>>
> >>> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> >>> index 0f7fdb99c809..2e9319ee1b74 100644
> >>> --- a/drivers/mfd/omap-usb-tll.c
> >>> +++ b/drivers/mfd/omap-usb-tll.c
> >>> @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >>>  	struct device				*dev =  &pdev->dev;
> >>>  	struct usbtll_omap			*tll;
> >>>  	void __iomem				*base;
> >>> -	int					i, nch, ver;
> >>> +	int					i, nch, ver, err;
> >>>  
> >>>  	dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
> >>>  
> >>> @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> >>>  					"usb_tll_hs_usb_ch%d_clk", i);
> >>>  		tll->ch_clk[i] = clk_get(dev, clkname);
> >>>  
> >>> -		if (IS_ERR(tll->ch_clk[i]))
> >>> +		if (IS_ERR(tll->ch_clk[i])) {
> >>>  			dev_dbg(dev, "can't get clock : %s\n", clkname);  
> > 
> > if you want dev_err() later, then why not here?  
> 
> Because clk is optional. If it is not there then we should not complain.
> But if it is there then it needs to be enabled successfully.
> 
I guess you mean *prepared*, the clock is enabled later (with error
checking). But your reasoning makes sense.

> >   
> >>> -		else
> >>> -			clk_prepare(tll->ch_clk[i]);
> >>> +		} else {
> >>> +			err = clk_prepare(tll->ch_clk[i]);
> >>> +			if (err)
> >>> +				dev_dbg(dev, "clock prepare error for: %s\n", clkname);    
> >>
> >> dev_err()?
> >>  
> > So why do you want a different return handling here? (I doubt there is
> > any clock having a real prepare() involved here)
> > 
> > As said in an earlier incarnation of this patch, the real question is
> > whether having partial clocks available is a valid operating scenario.
> > If yes, then the error should be ignored. If no, then bailing out early
> > is a good idea.  
> 
> In the DT binding, clocks is optional. So if it doesn't exist it is not
> an error condition.
> 
> > 
> > clk_prepare() errors are catched by failing clk_enable() later,
> > ch_clk[i] is checked later, too.
> >   
> >> I think we should return the error in this case.
> >> (after unpreparing the prepared clocks and clk_put())
> >>  
> > and pm_runtime_put_sync(dev) 

which can probably be done before dealing with the clocks. It is only
needed for the register access. 

Regards,
Andreas

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Karol P]

On Tue, 26 Nov 2024 at 23:06, Andreas Kemnade <andreas@kemnade.info> wrote:
>
> Am Tue, 19 Nov 2024 16:16:42 +0200
> schrieb Roger Quadros <rogerq@kernel.org>:
>
> > On 19/11/2024 15:56, Andreas Kemnade wrote:
> > > Am Tue, 19 Nov 2024 15:10:23 +0200
> > > schrieb Roger Quadros <rogerq@kernel.org>:
> > >
> > >> Hi,
> > >>
> > >> On 13/11/2024 23:16, Karol Przybylski wrote:
> > >>> clk_prepare() is called in usbtll_omap_probe to fill clk array.
> > >>> Return code is not checked, leaving possible error condition unhandled.
> > >>>
> > >>> Added variable to hold return value from clk_prepare() and dev_dbg statement
> > >>> when it's not successful.
> > >>>
> > >>> Found in coverity scan, CID 1594680
> > >>>
> > >>> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> > >>> ---
> > >>>  drivers/mfd/omap-usb-tll.c | 11 +++++++----
> > >>>  1 file changed, 7 insertions(+), 4 deletions(-)
> > >>>
> > >>> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> > >>> index 0f7fdb99c809..2e9319ee1b74 100644
> > >>> --- a/drivers/mfd/omap-usb-tll.c
> > >>> +++ b/drivers/mfd/omap-usb-tll.c
> > >>> @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> > >>>   struct device                           *dev =  &pdev->dev;
> > >>>   struct usbtll_omap                      *tll;
> > >>>   void __iomem                            *base;
> > >>> - int                                     i, nch, ver;
> > >>> + int                                     i, nch, ver, err;
> > >>>
> > >>>   dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
> > >>>
> > >>> @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> > >>>                                   "usb_tll_hs_usb_ch%d_clk", i);
> > >>>           tll->ch_clk[i] = clk_get(dev, clkname);
> > >>>
> > >>> -         if (IS_ERR(tll->ch_clk[i]))
> > >>> +         if (IS_ERR(tll->ch_clk[i])) {
> > >>>                   dev_dbg(dev, "can't get clock : %s\n", clkname);
> > >
> > > if you want dev_err() later, then why not here?
> >
> > Because clk is optional. If it is not there then we should not complain.
> > But if it is there then it needs to be enabled successfully.
> >
> I guess you mean *prepared*, the clock is enabled later (with error
> checking). But your reasoning makes sense.
>
> > >
> > >>> -         else
> > >>> -                 clk_prepare(tll->ch_clk[i]);
> > >>> +         } else {
> > >>> +                 err = clk_prepare(tll->ch_clk[i]);
> > >>> +                 if (err)
> > >>> +                         dev_dbg(dev, "clock prepare error for: %s\n", clkname);
> > >>
> > >> dev_err()?
> > >>
> > > So why do you want a different return handling here? (I doubt there is
> > > any clock having a real prepare() involved here)
> > >
> > > As said in an earlier incarnation of this patch, the real question is
> > > whether having partial clocks available is a valid operating scenario.
> > > If yes, then the error should be ignored. If no, then bailing out early
> > > is a good idea.
> >
> > In the DT binding, clocks is optional. So if it doesn't exist it is not
> > an error condition.
> >
> > >
> > > clk_prepare() errors are catched by failing clk_enable() later,
> > > ch_clk[i] is checked later, too.
> > >
> > >> I think we should return the error in this case.
> > >> (after unpreparing the prepared clocks and clk_put())
> > >>
> > > and pm_runtime_put_sync(dev)
>
> which can probably be done before dealing with the clocks. It is only
> needed for the register access.

I'm fairly new to this subsystem and I'm trying to understand the
conclusion. In the end, we should add dev_err() here after
clk_prepare() with appropriate handling?

>
> Regards,
> Andreas

Best regards,
Karol

Re: [PATCH] mfd: omap-usb-tll: check clk_prepare return code

[Andreas Kemnade]

Am Thu, 5 Dec 2024 22:54:05 +0100
schrieb Karol P <karprzy7@gmail.com>:

> On Tue, 26 Nov 2024 at 23:06, Andreas Kemnade <andreas@kemnade.info> wrote:
> >
> > Am Tue, 19 Nov 2024 16:16:42 +0200
> > schrieb Roger Quadros <rogerq@kernel.org>:
> >  
> > > On 19/11/2024 15:56, Andreas Kemnade wrote:  
> > > > Am Tue, 19 Nov 2024 15:10:23 +0200
> > > > schrieb Roger Quadros <rogerq@kernel.org>:
> > > >  
> > > >> Hi,
> > > >>
> > > >> On 13/11/2024 23:16, Karol Przybylski wrote:  
> > > >>> clk_prepare() is called in usbtll_omap_probe to fill clk array.
> > > >>> Return code is not checked, leaving possible error condition unhandled.
> > > >>>
> > > >>> Added variable to hold return value from clk_prepare() and dev_dbg statement
> > > >>> when it's not successful.
> > > >>>
> > > >>> Found in coverity scan, CID 1594680
> > > >>>
> > > >>> Signed-off-by: Karol Przybylski <karprzy7@gmail.com>
> > > >>> ---
> > > >>>  drivers/mfd/omap-usb-tll.c | 11 +++++++----
> > > >>>  1 file changed, 7 insertions(+), 4 deletions(-)
> > > >>>
> > > >>> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
> > > >>> index 0f7fdb99c809..2e9319ee1b74 100644
> > > >>> --- a/drivers/mfd/omap-usb-tll.c
> > > >>> +++ b/drivers/mfd/omap-usb-tll.c
> > > >>> @@ -202,7 +202,7 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> > > >>>   struct device                           *dev =  &pdev->dev;
> > > >>>   struct usbtll_omap                      *tll;
> > > >>>   void __iomem                            *base;
> > > >>> - int                                     i, nch, ver;
> > > >>> + int                                     i, nch, ver, err;
> > > >>>
> > > >>>   dev_dbg(dev, "starting TI HSUSB TLL Controller\n");
> > > >>>
> > > >>> @@ -248,10 +248,13 @@ static int usbtll_omap_probe(struct platform_device *pdev)
> > > >>>                                   "usb_tll_hs_usb_ch%d_clk", i);
> > > >>>           tll->ch_clk[i] = clk_get(dev, clkname);
> > > >>>
> > > >>> -         if (IS_ERR(tll->ch_clk[i]))
> > > >>> +         if (IS_ERR(tll->ch_clk[i])) {
> > > >>>                   dev_dbg(dev, "can't get clock : %s\n", clkname);  
> > > >
> > > > if you want dev_err() later, then why not here?  
> > >
> > > Because clk is optional. If it is not there then we should not complain.
> > > But if it is there then it needs to be enabled successfully.
> > >  
> > I guess you mean *prepared*, the clock is enabled later (with error
> > checking). But your reasoning makes sense.
> >  
> > > >  
> > > >>> -         else
> > > >>> -                 clk_prepare(tll->ch_clk[i]);
> > > >>> +         } else {
> > > >>> +                 err = clk_prepare(tll->ch_clk[i]);
> > > >>> +                 if (err)
> > > >>> +                         dev_dbg(dev, "clock prepare error for: %s\n", clkname);  
> > > >>
> > > >> dev_err()?
> > > >>  
> > > > So why do you want a different return handling here? (I doubt there is
> > > > any clock having a real prepare() involved here)
> > > >
> > > > As said in an earlier incarnation of this patch, the real question is
> > > > whether having partial clocks available is a valid operating scenario.
> > > > If yes, then the error should be ignored. If no, then bailing out early
> > > > is a good idea.  
> > >
> > > In the DT binding, clocks is optional. So if it doesn't exist it is not
> > > an error condition.
> > >  
> > > >
> > > > clk_prepare() errors are catched by failing clk_enable() later,
> > > > ch_clk[i] is checked later, too.
> > > >  
> > > >> I think we should return the error in this case.
> > > >> (after unpreparing the prepared clocks and clk_put())
> > > >>  
> > > > and pm_runtime_put_sync(dev)  
> >
> > which can probably be done before dealing with the clocks. It is only
> > needed for the register access.  
> 
> I'm fairly new to this subsystem and I'm trying to understand the
> conclusion. In the end, we should add dev_err() here after
> clk_prepare() with appropriate handling?
> 
we must make sure pm_runtime_put/get are paired and _put is called in
any case. Looking around a bit:
I think a good solution would be along this lines:
https://lore.kernel.org/linux-omap/34ab5f0b78c2869cc43797a72d6a2f40d9b246f3.camel@siemens.com/T/#u

using devm_clk_get_prepared() things can be simplified.

Regards,
Andreas