From: Jakub Kicinski <kuba@kernel.org>
To: Joel Stanley <joel@jms.id.au>
Cc: Dylan Hung <dylan_hung@aspeedtech.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
"David S . Miller" <davem@davemloft.net>,
netdev@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Po-Yu Chuang <ratbert@faraday-tech.com>,
linux-aspeed <linux-aspeed@lists.ozlabs.org>,
OpenBMC Maillist <openbmc@lists.ozlabs.org>,
BMC-SW <BMC-SW@aspeedtech.com>
Subject: Re: [PATCH] net: ftgmac100: Fix missing TX-poll issue
Date: Mon, 19 Oct 2020 12:00:40 -0700 [thread overview]
Message-ID: <20201019120040.3152ea0b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <CACPK8Xfn+Gn0PHCfhX-vgLTA6e2=RT+D+fnLF67_1j1iwqh7yg@mail.gmail.com>
On Mon, 19 Oct 2020 08:57:03 +0000 Joel Stanley wrote:
> > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
> > index 00024dd41147..9a99a87f29f3 100644
> > --- a/drivers/net/ethernet/faraday/ftgmac100.c
> > +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> > @@ -804,7 +804,8 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
> > * before setting the OWN bit on the first descriptor.
> > */
> > dma_wmb();
> > - first->txdes0 = cpu_to_le32(f_ctl_stat);
> > + WRITE_ONCE(first->txdes0, cpu_to_le32(f_ctl_stat));
> > + READ_ONCE(first->txdes0);
>
> I understand what you're trying to do here, but I'm not sure that this
> is the correct way to go about it.
>
> It does cause the compiler to produce a store and then a load.
+1 @first is system memory from dma_alloc_coherent(), right?
You shouldn't have to do this. Is coherent DMA memory broken
on your platform?
WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Joel Stanley <joel@jms.id.au>
Cc: BMC-SW <BMC-SW@aspeedtech.com>,
linux-aspeed <linux-aspeed@lists.ozlabs.org>,
Po-Yu Chuang <ratbert@faraday-tech.com>,
netdev@vger.kernel.org,
OpenBMC Maillist <openbmc@lists.ozlabs.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Dylan Hung <dylan_hung@aspeedtech.com>,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH] net: ftgmac100: Fix missing TX-poll issue
Date: Mon, 19 Oct 2020 12:00:40 -0700 [thread overview]
Message-ID: <20201019120040.3152ea0b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <CACPK8Xfn+Gn0PHCfhX-vgLTA6e2=RT+D+fnLF67_1j1iwqh7yg@mail.gmail.com>
On Mon, 19 Oct 2020 08:57:03 +0000 Joel Stanley wrote:
> > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
> > index 00024dd41147..9a99a87f29f3 100644
> > --- a/drivers/net/ethernet/faraday/ftgmac100.c
> > +++ b/drivers/net/ethernet/faraday/ftgmac100.c
> > @@ -804,7 +804,8 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct sk_buff *skb,
> > * before setting the OWN bit on the first descriptor.
> > */
> > dma_wmb();
> > - first->txdes0 = cpu_to_le32(f_ctl_stat);
> > + WRITE_ONCE(first->txdes0, cpu_to_le32(f_ctl_stat));
> > + READ_ONCE(first->txdes0);
>
> I understand what you're trying to do here, but I'm not sure that this
> is the correct way to go about it.
>
> It does cause the compiler to produce a store and then a load.
+1 @first is system memory from dma_alloc_coherent(), right?
You shouldn't have to do this. Is coherent DMA memory broken
on your platform?
next prev parent reply other threads:[~2020-10-19 19:00 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 7:39 [PATCH] net: ftgmac100: Fix missing TX-poll issue Dylan Hung
2020-10-19 7:39 ` Dylan Hung
2020-10-19 8:57 ` Joel Stanley
2020-10-19 8:57 ` Joel Stanley
2020-10-19 9:19 ` Dylan Hung
2020-10-19 9:19 ` Dylan Hung
2020-10-19 19:00 ` Jakub Kicinski [this message]
2020-10-19 19:00 ` Jakub Kicinski
2020-10-19 23:23 ` Benjamin Herrenschmidt
2020-10-19 23:23 ` Benjamin Herrenschmidt
2020-10-20 2:57 ` Jakub Kicinski
2020-10-20 2:57 ` Jakub Kicinski
2020-10-20 6:15 ` Benjamin Herrenschmidt
2020-10-20 6:15 ` Benjamin Herrenschmidt
2020-10-20 17:24 ` Jakub Kicinski
2020-10-20 17:24 ` Jakub Kicinski
2020-10-20 6:14 ` Dylan Hung
2020-10-20 6:14 ` Dylan Hung
2020-10-20 13:15 ` David Laight
2020-10-20 13:15 ` David Laight
2020-10-20 22:05 ` Benjamin Herrenschmidt
2020-10-20 22:05 ` Benjamin Herrenschmidt
2020-10-20 19:49 ` Arnd Bergmann
2020-10-20 22:10 ` Benjamin Herrenschmidt
2020-10-20 22:10 ` Benjamin Herrenschmidt
2020-10-20 22:25 ` Andrew Jeffery
2020-10-23 13:08 ` Dylan Hung
2020-10-26 22:21 ` Benjamin Herrenschmidt
2020-10-27 2:18 ` Joel Stanley
2020-10-27 2:18 ` Joel Stanley
2020-10-21 7:16 ` Arnd Bergmann
2020-10-21 12:11 ` Arnd Bergmann
2020-10-21 12:11 ` Arnd Bergmann
2020-10-22 7:40 ` Benjamin Herrenschmidt
2020-10-22 7:40 ` Benjamin Herrenschmidt
2020-10-23 8:39 ` Arnd Bergmann
2020-10-23 8:39 ` Arnd Bergmann
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