Am Montag, 9. April 2018, 17:53:01 CEST schrieb Robin Murphy:

On 09/04/18 16:44, Heiko Stübner wrote:

quoted

Hi Tomeu,

Am Montag, 9. April 2018, 16:41:56 CEST schrieb Tomeu Vizoso:

quoted

in today's linux-next, the DRM driver fails to probe because the iommu
driver fails to find the aclk. I need to apply this patch for things
to work again.

Thanks for catching that issue.

This seems to expose a backwards-compatibility issue, as this breaks
all old devicetrees, so should get a proper fix, apart from me applying
the dt-patch I missed.

Looking at the iommu-clock-handling patch, I imagine this part as
the culprit:

+	iommu->num_clocks = ARRAY_SIZE(rk_iommu_clocks);
+	iommu->clocks = devm_kcalloc(iommu->dev, iommu->num_clocks,
+				     sizeof(*iommu->clocks), GFP_KERNEL);
+	if (!iommu->clocks)
+		return -ENOMEM;

The clk-bulk functions seem to work with simple for loops and
should (as the other standard clock functions) just work fine with
an empty struct, so I guess a simple

	if (!iommu->clocks && iommu->num_clocks > 0)
	
		return -ENOMEM;

should hopefully be enough. I'll try to give this a test later on
if nobody beats me to it :-)

But iommu->num_clocks is clearly set to a nonzero compile-time constant
at this point ;)

I'd assume it's the return from devm_clk_bulk_get() which needs to
special-case the "no clocks found" case from any other error, and *then*
blat num_clocks to 0 if so.

you're right of course. Looking at it again, I now clearly see the ARRAY_SIZE
and am wondering what made me think num_clocks would be runtime-read.

Must be those 25°C today ;-)