Messages in this thread | | | Subject | Re: [PATCH] USB: host: ehci: Add error handlinginehci_mxc_drv_probe() | From | Tang Bin <> | Date | Sat, 9 May 2020 09:13:22 +0800 |
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Hi Sergei:
On 2020/5/9 4:27, Sergei Shtylyov wrote: > On 05/08/2020 06:03 PM, Tang Bin wrote: > >>>>> On Fri, May 08, 2020 at 07:44:53PM +0800, Tang Bin wrote: >>>>>> The function ehci_mxc_drv_probe() does not perform sufficient error >>>>>> checking after executing platform_get_irq(), thus fix it. >>>>>> >>>>>> Fixes: 7e8d5cd93fa ("USB: Add EHCI support for MX27 and MX31 based boards") >>>>>> Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com> >>>>>> Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com> >>>>>> --- >>>>>> drivers/usb/host/ehci-mxc.c | 2 ++ >>>>>> 1 file changed, 2 insertions(+) >>>>>> >>>>>> diff --git a/drivers/usb/host/ehci-mxc.c b/drivers/usb/host/ehci-mxc.c >>>>>> index a1eb5ee77..a0b42ba59 100644 >>>>>> --- a/drivers/usb/host/ehci-mxc.c >>>>>> +++ b/drivers/usb/host/ehci-mxc.c >>>>>> @@ -50,6 +50,8 @@ static int ehci_mxc_drv_probe(struct platform_device *pdev) >>>>>> } >>>>>> irq = platform_get_irq(pdev, 0); >>>>>> + if (irq < 0) >>>>>> + return irq; >>>>> <= ? >>>> In the file 'drivers/base/platform.c', the function platform_get_irq() is >>>> explained and used as follows: >>>> >>>> * Gets an IRQ for a platform device and prints an error message if >>>> finding the >>>> * IRQ fails. Device drivers should check the return value for errors so >>>> as to >>>> * not pass a negative integer value to the request_irq() APIs. >>>> * >>>> * Example: >>>> * int irq = platform_get_irq(pdev, 0); >>>> * if (irq < 0) >>>> * return irq; >>>> * >>>> * Return: IRQ number on success, negative error number on failure. >>>> >>>> And in my hardware experiment, even if I set the irq failed deliberately in >>>> the DTS, the returned value is negative instead of zero. >>> Please read the thread at >>> https://lore.kernel.org/r/20200501224042.141366-1-helgaas%40kernel.org >>> for more details about this. >>> >> Great, It looks beautiful, finally someone took a knife to the file 'platform.c'. > I thought I did that already couple years ago, when returned 0 from platform_get_irq() could mean both IRQ # and error... :-) Can you tell me what platform can returned 0? I want to do this test in the hardware. >> I have been studied this place for a long time, and don't know what platform can return 0, which made me curious. >> >> So the example should be: >> >> * int irq = platform_get_irq(pdev, 0); >> * if (irq <= 0) >> * return irq; > And you then return 0 (success) as if your probe() succeeded. Congratulations! :-P
Thanks,
Tang Bin
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