Re: [PATCH V5 0/4] coresight: trbe: Enable ACPI based devices

[Will Deacon]

On Sun, Aug 27, 2023 at 11:11:16PM +0100, Suzuki K Poulose wrote:
> On 21/08/2023 12:28, Will Deacon wrote:
> > Hmm, the rationale behind your change to make the pdata allocation
> > per-device in ("coresight: trbe: Allocate platform data per device")
> > confuses me: with Anshuman's change to allocate the pdata using
> > devm_kzalloc(), there shouldn't be any connections for the coresight
> > core to trip over, should there?
> 
> Anshuman's patch is working around the problem of "TRBE platform
> device with ACPI doesn't have a valid companion device" - this is a problem
> for the acpi_get_coresight_platform_data(). The work
> around is to move the "allocation" from coresight_get_platform_data()
> to the driver (given we don't need anything else from the ACPI except
> the IRQ). That doesn't change *how* it is allocated.
> Also please note that, the TRBE driver creates a TRBE coresight_device
> per-CPU and the platform data is shared by all of these devices, which
> the coresight core driver doesn't cope with. The other option is to
> move the releasing of these platform-data to the individual drivers,
> which is quite an invasive change. Or, make the core driver tolerate
> a NULL platform data, which is also again invasive. So the merged fix
> is correct and is still valid after this patch.

Ah, ok, so the problem with TRBE isn't anything to do with its connections,
but simply because the pdata is shared?

Will