mfd: omap-usb-tll: check clk_prepare return code

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

Posted by Karol Przybylski 1 week, 2 days ago

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

Posted by Roger Quadros 3 days, 13 hours ago

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

Posted by Andreas Kemnade 3 days, 12 hours ago

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

Posted by Roger Quadros 3 days, 11 hours ago


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