Re: [PATCH 1/2] iommu/arm-smmu-v3: Don't display an error when IRQ lines are missing

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

Hi John,

On Mon, Nov 11, 2019 at 11:52:38AM +0000, John Garry wrote:
> On 11/11/2019 11:17, Jean-Philippe Brucker wrote:
> > Since commit 7723f4c5ecdb ("driver core: platform: Add an error message
> > to platform_get_irq*()"), platform_get_irq_byname() displays an error
> > when the IRQ isn't found. Since the SMMUv3 driver uses that function to
> > query which interrupt method is available, the message is now displayed
> > during boot for any SMMUv3 that doesn't implement the combined
> > interrupt, or that implements MSIs.
> > 
> > [   20.700337] arm-smmu-v3 arm-smmu-v3.7.auto: IRQ combined not found
> > [   20.706508] arm-smmu-v3 arm-smmu-v3.7.auto: IRQ eventq not found
> > [   20.712503] arm-smmu-v3 arm-smmu-v3.7.auto: IRQ priq not found
> > [   20.718325] arm-smmu-v3 arm-smmu-v3.7.auto: IRQ gerror not found
> > 
> > Use platform_get_irq_byname_optional() to avoid displaying a spurious
> > error.
> > 
> > Fixes: 7723f4c5ecdb ("driver core: platform: Add an error message to platform_get_irq*()")
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> 
> That stops a nuisance:
> Tested-by: John Garry <john.garry@huawei.com>

Thanks

> However, I will say though that the combined irq seems necessary for TX2,
> which is not warned about being missing now.

I don't think we warned about this before commit 7723f4c5ecdb either.
There are some warnings later in arm_smmu_setup_irqs() if the firmware
didn't describe any wiring at all, but we don't check whether the TX2 does
have the combined interrupt. Personally I wouldn't tie this to one SMMU
implementation because it would prevent from supporting a (hypothetical)
platform that integrates the same SMMU but "fixes" the IRQ lines.

> Finally, A cover letter would have been handy to mention that the new API
> was only introduced after rc1

Oh, I didn't even notice that, I thought it was introduced by rc1. I'll
add a cover if I send a v2.

Thanks,
Jean

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel