Re: [dpdk-dev] [dpdk-stable] [PATCH] net/nfp: fix minimum descriptor sizes

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 8/23/2021 8:59 AM, heinrich.kuhn@corigine.com wrote:
> From: Heinrich Kuhn <heinrich.kuhn@corigine.com>
> 
> The NFP4000/6000 supports a minimum of 256 Tx/Rx descriptors and not 64.
> Before this patch when a DPDK application configured < 256 Tx
> descriptors the hardware read/write pointers would be unmasked and not
> wrapped at the expected size of the ring. The PMD logic to determine the
> amount of free space in the Tx ring is incompatible with the unmasked
> hwqueue pointers and this will result in the PMD not updating the
> read pointer at all.The knock-on effect is that under high load the
> PMD will potentially re-use a Tx descriptor before the hw has had a
> chance to process that particular descriptor. This issue can manifest as
> a DMA error when the hardware tries to perform a DMA with info from a
> partially populated descriptor.
> 
> Fixes: defb9a5dd156 ("nfp: introduce driver initialization")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Heinrich Kuhn <heinrich.kuhn@corigine.com>
> Signed-off-by: Simon Horman <simon.horman@corigine.com>

Applied to dpdk-next-net/main, thanks.