From: Jakub Kicinski <kuba@kernel.org>
To: Lorenzo Bianconi <lorenzo@kernel.org>
Cc: Felix Fietkau <nbd@nbd.name>, Sean Wang <sean.wang@mediatek.com>,
Mark Lee <Mark-MC.Lee@mediatek.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, netdev@vger.kernel.org,
upstream@airoha.com
Subject: Re: [PATCH net-next v2] net: airoha: Implement BQL support
Date: Tue, 15 Oct 2024 09:09:52 -0700 [thread overview]
Message-ID: <20241015090952.6bcb5856@kernel.org> (raw)
In-Reply-To: <Zw6QUxpdnJtorc_e@lore-desk>
On Tue, 15 Oct 2024 17:54:59 +0200 Lorenzo Bianconi wrote:
> > Oh, thought its called on stop. In that case we're probably good
> > from BQL perspective.
> >
> > But does it mean potentially very stale packets can sit on the Tx
> > ring when the device is stopped, until it's started again?
>
> Do you mean the packets that the stack is transmitting when the .ndo_stop()
> is run?
Whatever is in the queue at the time ndo_stop() gets called.
Could be the full descriptor ring I presume?
> In airoha_dev_stop() we call netif_tx_disable() to disable the transmission
> on new packets and inflight packets will be consumed by the completion napi,
> is it not enough?
They will only get consumed if the DMA gets to them right?
Stop seems to stop the DMA.
> I guess we can even add netdev_tx_reset_subqueue() for all netdev
> queues in airoha_dev_stop(), I do not have a strong opinion about it. What
> do you prefer?
So to be clear I think this patch is correct as of the current driver
code. I'm just wondering if we should call airoha_qdma_cleanup_tx_queue()
on stop as well, and then that should come with the reset.
I think having a packet stuck in a queue may lead to all sort of oddness
so my recommendation would be to flush the queues.
next prev parent reply other threads:[~2024-10-15 16:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-12 9:01 [PATCH net-next v2] net: airoha: Implement BQL support Lorenzo Bianconi
2024-10-15 14:32 ` Jakub Kicinski
2024-10-15 14:39 ` Lorenzo Bianconi
2024-10-15 14:52 ` Jakub Kicinski
2024-10-15 15:54 ` Lorenzo Bianconi
2024-10-15 16:09 ` Jakub Kicinski [this message]
2024-10-15 16:35 ` Lorenzo Bianconi
2024-10-15 16:49 ` Jakub Kicinski
2024-10-15 17:10 ` patchwork-bot+netdevbpf
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