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

From: Roger Quadros
Date: Fri Oct 02 2020 - 06:06:34 EST


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.

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


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