linux-kernel - Re: [PATCH v3] PCI: dwc: dra7xx: Fix compilation warning.

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Date:   Fri, 16 Jun 2017 13:48:32 +0530
From:   Arvind Yadav <arvind.yadav.cs@...il.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     kishon@...com, bhelgaas@...gle.com, linux-omap@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] PCI: dwc: dra7xx: Fix compilation warning.

Hi Kishon/Bjorn,

What is correct Setting for these two PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI 
and
PCIECTRL_DRA7XX_CONF_IRQSTATUS_MAIN register.

Value of register After change:
  register[PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI] = LEG_EP_INTERRUPTS |  MSI
                                           = 0x1f
register[PCIECTRL_DRA7XX_CONF_IRQSTATUS_MAIN] =  INTERRUPTS
                   =  0x1fff
Is this correct?

Thanks
~arvind

On Friday 16 June 2017 02:19 AM, Bjorn Helgaas wrote:
> On Thu, Jun 15, 2017 at 02:19:20PM +0530, Arvind Yadav wrote:
>> drivers/pci/dwc/pci-dra7xx.c: In function ‘dra7xx_pcie_enable_msi_interrupts’:
>> drivers/pci/dwc/pci-dra7xx.c:177:7: warning: large integer implicitly truncated to unsigned type [-Woverflow]
>>         ~LEG_EP_INTERRUPTS & ~MSI);
>>         ^
>> drivers/pci/dwc/pci-dra7xx.c: In function ‘dra7xx_pcie_enable_wrapper_interrupts’:
>> drivers/pci/dwc/pci-dra7xx.c:187:7: warning: large integer implicitly truncated to unsigned type [-Woverflow]
>>         ~INTERRUPTS);
> I don't object to the patch itself (hopefully Kishon will verify that
> it's correct), but the subject and changelog are now completely wrong.
>
> If the patch is correct, it is now a bug fix and is not at all about
> fixing a compilation warning.  We used to write
>
>    ~LEG_EP_INTERRUPTS & ~MSI
>    ~(INTA | INTB | INTC | INTD) & ~MSI
>    ~(BIT(0) | BIT(1) | BIT(2) | BIT(3)) & ~(BIT(4))
>    ~(0x1 | 0x2 | 0x4 | 0x8) & ~(0x10)
>    ~(0xf) & ~(0x10)
>    0xfffffff0 & 0xffffffef
>    0xffffffe0
>
> and now we write
>
>    LEG_EP_INTERRUPTS | MSI
>    ...
>    0x1f
>
> It is about using these two registers correctly, and the fact that the
> compilation warning goes away is a happy coincidence but not even
> worth mentioning in the changelog.
>
> So, if Kishon acks the content of the patch, please post this again
> with an updated subject and changelog.
>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>> Changes in v2:
>>               Add casts in the definitions.
>> Changes in v3:
>>               Change logic insted of casting.
>>
>>   drivers/pci/dwc/pci-dra7xx.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
>> index 8decf46..668dc15 100644
>> --- a/drivers/pci/dwc/pci-dra7xx.c
>> +++ b/drivers/pci/dwc/pci-dra7xx.c
>> @@ -174,7 +174,7 @@ static int dra7xx_pcie_establish_link(struct dw_pcie *pci)
>>   static void dra7xx_pcie_enable_msi_interrupts(struct dra7xx_pcie *dra7xx)
>>   {
>>   	dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI,
>> -			   ~LEG_EP_INTERRUPTS & ~MSI);
>> +			   LEG_EP_INTERRUPTS | MSI);
>>   
>>   	dra7xx_pcie_writel(dra7xx,
>>   			   PCIECTRL_DRA7XX_CONF_IRQENABLE_SET_MSI,
>> @@ -184,7 +184,7 @@ static void dra7xx_pcie_enable_msi_interrupts(struct dra7xx_pcie *dra7xx)
>>   static void dra7xx_pcie_enable_wrapper_interrupts(struct dra7xx_pcie *dra7xx)
>>   {
>>   	dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MAIN,
>> -			   ~INTERRUPTS);
>> +			   INTERRUPTS);
>>   	dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_IRQENABLE_SET_MAIN,
>>   			   INTERRUPTS);
>>   }
>> -- 
>> 1.9.1
>>