Haren Myneni's on March 19, 2020 4:19 pm:
>
> NX expects OS to return credit for send window after processing each
> fault. Also credit has to be returned even for fault window.
And this should be merged in the fault handler function.
>
> Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
> Signed-off-by: Haren Myneni <ha...@linux.ibm.com>
> ---
> arch/powerpc/platforms/powernv/vas-fault.c | 9 +++++++++
> arch/powerpc/platforms/powernv/vas-window.c | 17 +++++++++++++++++
> arch/powerpc/platforms/powernv/vas.h | 1 +
> 3 files changed, 27 insertions(+)
>
> diff --git a/arch/powerpc/platforms/powernv/vas-fault.c
> b/arch/powerpc/platforms/powernv/vas-fault.c
> index 40e1de4..292f7ba 100644
> --- a/arch/powerpc/platforms/powernv/vas-fault.c
> +++ b/arch/powerpc/platforms/powernv/vas-fault.c
> @@ -238,6 +238,10 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data)
> memcpy(crb, fifo, CRB_SIZE);
> entry->stamp.nx.pswid = cpu_to_be32(FIFO_INVALID_ENTRY);
> entry->ccw |= cpu_to_be32(CCW0_INVALID);
> + /*
> + * Return credit for the fault window.
> + */
None of the comments in this patch are useful.
> + vas_return_credit(vinst->fault_win, 0);
Can you use true/false for bools?
> mutex_unlock(&vinst->mutex);
>
> pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d\n",
> @@ -267,6 +271,11 @@ irqreturn_t vas_fault_thread_fn(int irq, void *data)
> }
>
> update_csb(window, crb);
> + /*
> + * Return credit for send window after processing
> + * fault CRB.
> + */
Any chance of a little bit of explanation how the credit system works?
Or is it in the code somewhere already?
I don't suppose there is a chance to batch credit updates with multiple
faults? (maybe the MMIO is insignificant)
> + vas_return_credit(window, 1);
> } while (true);
> }
>
Thanks,
Nick
