Re: [PATCH v5 01/10] arm_mpam: let low level MSC accessors return an error

Ben Horgan <[email protected]> Thu, 30 Jul 2026 12:20:14 +0100
Newsgroups org.kernel.vger.linux-acpi,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel
Message-ID <[email protected]>
Hi Andre,

On 7/29/26 14:41, Andre Przywara wrote:
> The upcoming MPAM-Fb support does not use MMIO primitives to access an
> MSC, but employs a shared-memory/doorbell based firmware protocol.
> Its complexity means that it must be able to handle errors, whereas we
> always assume an MMIO based MSC access succeeds today.
> 
> Change the __mpam_read_reg() low level accessor function to return the
> requested data through a pointer, and return an error code instead.
> Also change the __mpam_write_reg() accessor function to return an error
> code. At the moment this is always 0, so all error handling paths are
> not exercised at the moment. This will change later when alternative
> MSC access methods like MPAM-Fb are activated.
> 
> Change all direct users of those MSC wrappers to comply with the new
> prototypes, though the errors are not propagated all the way up yet.
> 
> Signed-off-by: Andre Przywara <[email protected]>
> Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Ben Horgan <[email protected]>

Thanks,

Ben