Re: [PATCH] usb: cdns3: platform_get_irq_byname_optional instead platform_get_irq_byname

[Roger Quadros]

Pawel,

On 05/10/2020 08:54, Pawel Laszczak wrote:
> Roger,
> > Pawel,
> >
> > On 02/10/2020 12:08, Pawel Laszczak wrote:
> > > Roger,
> > >
> > > > On 30/09/2020 09:57, Pawel Laszczak wrote:
> > > > > To avoid duplicate error information patch replaces platform_get_irq_byname
> > > > > into platform_get_irq_byname_optional.
> > > >
> > > > What is duplicate error information?
> > >
> > > The function platform_get_irq_byname print:
> > > " dev_err(&dev->dev, "IRQ %s not found\n", name);" if error occurred.
> > >
> > > In core.c we have the another error message below invoking this function.
> > > e.g
> > > 	if (cdns->dev_irq < 0)
> > > 		dev_err(dev, "couldn't get peripheral irq\n");
> > >
> > > So, it's looks like one dev_err is  redundant.
> >
> > If we want all 3 IRQs to be valid irrespective of dr_mode then we should
> > use platform_get_irq_byname() and error out in probe if (ret < 0 && ret != -EPROBE_DEFER).
> >
> > We can get rid of the irq check and duplicate error message in other places.
>
> To be sure we understand each other correctly.
>
> Are You suggesting  to leave the  platform_get_irq_byname()
> and rid of from core.c the following lines :
>
> if (cdns->dev_irq < 0)
> 	dev_err(dev, "couldn't get peripheral irq\n");
> 	
> and
>
> dev_err(dev, "couldn't get otg irq\n");
> ?

Yes.

> A word of explanation why this patch has been sent.
> During reviewing the cdnsp driver Chunfeng Yun add such comment:
>
> "
> > +	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
> > +	if (cdns->dev_irq == -EPROBE_DEFER)
> > +		return cdns->dev_irq;
> > +
> > +	if (cdns->dev_irq < 0)
> > +		dev_err(dev, "couldn't get peripheral irq\n");
> Use platform_get_irq_byname_optional? otherwise no need print this log,
> platform_get_irq_byname() will print it.
> "
>
> In this patch I've chosen the platform_get_irq_byname_optional because both
> function do the same but the error message from core.c tell us little more then
> generic message from platform_get_irq_byname.

Using platform_get_irq_byname_optional() says driver expects it is optional but
only to fail later. It will be confusing to new reader that's all. I leave it to
you to decide what approach to take.

cheers,
-roger

> > > > > A change was suggested during reviewing CDNSP driver by Chunfeng Yun.
> > > > >
> > > > > Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
> > > > > ---
> > > > >     drivers/usb/cdns3/core.c | 4 ++--
> > > > >     1 file changed, 2 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> > > > > index a0f73d4711ae..a3f6dc44cf3a 100644
> > > > > --- a/drivers/usb/cdns3/core.c
> > > > > +++ b/drivers/usb/cdns3/core.c
> > > > > @@ -465,7 +465,7 @@ static int cdns3_probe(struct platform_device *pdev)
> > > > >
> > > > >     	cdns->xhci_res[1] = *res;
> > > > >
> > > > > -	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
> > > > > +	cdns->dev_irq = platform_get_irq_byname_optional(pdev, "peripheral");
> > > >
> > > > As per DT binding document, these are mandatory properties
> > >
> > > I think that name platform_get_irq_byname_optional is little confusing.
> > > Function descriptions show that both are almost identical:
> > > /**
> > >    * platform_get_irq_byname_optional - get an optional IRQ for a device by name
> > >    * @dev: platform device
> > >    * @name: IRQ name
> > >    *
> > >    * Get an optional IRQ by name like platform_get_irq_byname(). Except that it
> > >    * does not print an error message if an IRQ can not be obtained.
> > >    *
> > >    * Return: non-zero IRQ number on success, negative error number on failure.
> > >    */
> > >
> > > >    - interrupts: Interrupts used by cdns3 controller:
> > > >           "host" - interrupt used by XHCI driver.
> > > >           "peripheral" - interrupt used by device driver
> > > >           "otg" - interrupt used by DRD/OTG  part of driver
> > > >
> > > > for dr_mode == "otg" -> all 3 are mandatory.
> > > > for dr_mode == "host" -> "otg" and "peripheral" IRQs are not required.
> > > > for dr_mode == "periphearal" -> "otg" and "host" IRQs are not required.
> > > >
> > > > >     	if (cdns->dev_irq == -EPROBE_DEFER)
> > > > >     		return cdns->dev_irq;
> > > > >
> > > > > @@ -477,7 +477,7 @@ static int cdns3_probe(struct platform_device *pdev)
> > > > >     		return PTR_ERR(regs);
> > > > >     	cdns->dev_regs	= regs;
> > > > >
> > > > > -	cdns->otg_irq = platform_get_irq_byname(pdev, "otg");
> > > > > +	cdns->otg_irq = platform_get_irq_byname_optional(pdev, "otg");
> > > > >     	if (cdns->otg_irq == -EPROBE_DEFER)
> > > > >     		return cdns->otg_irq;
> > >
> > > Regards,
> > > Pawel
> >
> > --
> > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki