Re: [RESEND PATCH v4 06/11] cxl/pci: Add the PMUs after configuring events

[Jonathan Cameron <jic23@kernel.org>]

On Wed,  5 Aug 2026 08:59:06 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> cxl_pci_probe() adds the CPMU instances before configuring the event
> interrupts. Both take an MSI/MSI-X vector the device names in its own
> capability registers, and the spec lets a device point several capabilities
> at one message number, so the two can collide.
> 
> They do not fail the same way. A failed devm_cxl_pmu_add() only breaks out
> of the loop, while a failed cxl_event_config() aborts probe and the memory
> device never appears. Going PMUs-first therefore lets a peripheral facility
> take the vector and deny it to one that matters.
> 
> Configure events first, so a collision costs the PMU rather than the
> memdev. Return 0 explicitly afterwards, since rc still holds any PMU error
> that cxl_event_config() used to overwrite on the way past.
> 
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v4:
> - New patch, ahead of the PMU dropping IRQF_SHARED. Without this that
>   change can turn a shared vector into a probe failure for the whole
>   memdev rather than a missing PMU (sashiko-bot).
Make sense. Anyone crazy enough to share this interrupt gets to keep
the pieces.

Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>