Re: [PATCH] mfd: omap-usb-tll: handle clk_prepare return code in usbtll_omap_probe

From: Roger Quadros
Date: Mon Nov 11 2024 - 09:42:00 EST


Hi,

On 10/11/2024 01:29, Andreas Kemnade wrote:
> Am Thu, 7 Nov 2024 12:12:52 +0100
> schrieb Karol P <karprzy7@xxxxxxxxx>:
>
>> On Thu, 7 Nov 2024 at 00:15, Andreas Kemnade <andreas@xxxxxxxxxxxx> wrote:
>>>
>>> Am Wed, 6 Nov 2024 23:33:24 +0100
>>> schrieb Karol Przybylski <karprzy7@xxxxxxxxx>:
>>>
>>>> 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 return statement
>>>> when it's not successful.
>>>>
>>>> Found in coverity scan, CID 1594680
>>>>
>>>> Signed-off-by: Karol Przybylski <karprzy7@xxxxxxxxx>
>>>> ---
>>>> drivers/mfd/omap-usb-tll.c | 8 ++++++--
>>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/mfd/omap-usb-tll.c b/drivers/mfd/omap-usb-tll.c
>>>> index 0f7fdb99c809..28446b082c85 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");
>>>>
>>>> @@ -251,7 +251,11 @@ static int usbtll_omap_probe(struct platform_device *pdev)
>>>> if (IS_ERR(tll->ch_clk[i]))
>>>> dev_dbg(dev, "can't get clock : %s\n", clkname);
>>>
>>> if you add more intensive error checking, then why is this error
>>> ignored and not returned?
>>
>> Thank you for the feedback. It does seem that elevated error checking
>> is not the way
>> to go in this case.
>
> As far as I can see everything checks ch_clk[i] for validity before
> usage. Also clk_enable() called later is checked which would catch
> clk_prepare() failures, if there were even possible here.
>
> So the only question which I am not 100% sure about is whether having
> ch_clk sparsly populated is normal operation. If that is the case, then
> more error checking is not useful. If not, then it might let us better
> sleep. As said as far as I can see errors are catched later.
>
> @Roger: what is your opintion towards this?

I don't see usb_tll_hs_usb_ch?_clk in any of the OMAP device trees.
Could it be that they are optional?
If so then we could convert it to devm_clk_get_optional()?

While at that, maybe the device tree binding could also be updated and
converted to yaml.

>
> BTW: If you do this kind of work, you could also use W=1 or
> CONFIG_WERROR during compiling to catch easy things. At least I see new
> compile warnings with your patch.
>
> Regards,
> Andreas

--
cheers,
-roger