From: Brian Norris <briannorris@chromium.org>
To: Tony Chuang <yhchuang@realtek.com>
Cc: Grant Grundler <grundler@chromium.org>,
Kalle Valo <kvalo@codeaurora.org>,
Johannes Berg <johannes@sipsolutions.net>,
"Larry.Finger@lwfinger.net" <Larry.Finger@lwfinger.net>,
Pkshih <pkshih@realtek.com>, Andy Huang <tehuang@realtek.com>,
"sgruszka@redhat.com" <sgruszka@redhat.com>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v4 03/13] rtw88: hci files
Date: Fri, 22 Mar 2019 14:36:21 +0000 [thread overview]
Message-ID: <20190322143621.2rtyzysglv4fqocf@penguin> (raw)
In-Reply-To: <F7CD281DE3E379468C6D07993EA72F84D17AA49B@RTITMBSVM04.realtek.com.tw>
[Following up a little late on this one]
Hi Grant and Tony,
On Wed, Feb 20, 2019 at 11:19:10AM +0000, Tony Chuang wrote:
> > -----Original Message-----
> > From: Grant Grundler [mailto:grundler@chromium.org]
> > This is another bug in the code actually: the code accessing tx
> > descriptor rings should be declared volatile since they are updated by
> > the device which is not visible to the compiler. Compiler won't
> > optimize (or reorder) volatile code (by "volatile code" I mean code
> > that is accessing data marked "volatile").
If I'm understanding the code correctly, the TX ISR assumes that
everything between the last entry we processed (ring->r.rp) and a
certain point (cur_rp) is complete. The former index was saved during
the previous interrupt and the latter is determined via a register read.
So assuming properly synchronized interrupts (such as with PCIe MSI) and
no device-/firmware-related ordering bugs, then I think we're OK -- the
only "volatile" piece is the register read, which already embeds
volatile in the IO accessors.
> This is fixed in PATCH v5. We reset and use rx tag to sync dma.
> So the polling can be removed and the bus timeout has not happened again.
Yes, I tested the later versions of this series, and I didn't see this
problem so far. I'll follow up there with my Review/Test information
eventually.
Thanks,
Brian
next prev parent reply other threads:[~2019-03-22 14:36 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 4:02 [PATCH v4 00/13] rtw88: mac80211 driver for Realtek 802.11ac wireless network chips yhchuang
2019-01-30 4:02 ` [PATCH v4 01/13] rtw88: main files yhchuang
2019-01-30 16:21 ` Larry Finger
2019-01-31 2:54 ` Tony Chuang
2019-01-30 4:02 ` [PATCH v4 02/13] rtw88: core files yhchuang
2019-01-30 4:02 ` [PATCH v4 03/13] rtw88: hci files yhchuang
2019-01-31 22:36 ` Brian Norris
2019-02-12 6:18 ` Tony Chuang
2019-02-12 22:04 ` Brian Norris
2019-02-13 8:08 ` Tony Chuang
2019-02-13 11:08 ` Tony Chuang
2019-02-13 19:21 ` Brian Norris
2019-02-14 23:05 ` Grant Grundler
2019-02-20 11:19 ` Tony Chuang
2019-03-22 14:36 ` Brian Norris [this message]
2019-02-08 22:28 ` Brian Norris
2019-02-11 6:15 ` Tony Chuang
2019-02-09 2:14 ` Brian Norris
2019-02-11 5:48 ` Tony Chuang
2019-02-11 17:56 ` Brian Norris
2019-01-30 4:02 ` [PATCH v4 04/13] rtw88: trx files yhchuang
2019-01-30 4:02 ` [PATCH v4 05/13] rtw88: mac files yhchuang
2019-01-30 4:02 ` [PATCH v4 06/13] rtw88: fw and efuse files yhchuang
2019-01-31 22:58 ` Brian Norris
2019-02-12 9:14 ` Tony Chuang
2019-01-30 4:02 ` [PATCH v4 07/13] rtw88: phy files yhchuang
2019-01-30 4:02 ` [PATCH v4 08/13] rtw88: debug files yhchuang
2019-02-01 19:49 ` Brian Norris
2019-02-11 5:41 ` Tony Chuang
2019-01-30 4:02 ` [PATCH v4 09/13] rtw88: chip files yhchuang
2019-01-30 19:44 ` Brian Norris
2019-01-31 11:36 ` Tony Chuang
2019-01-31 11:52 ` Kalle Valo
2019-01-31 11:55 ` Johannes Berg
2019-01-31 13:40 ` Kalle Valo
2019-01-30 4:02 ` [PATCH v4 10/13] rtw88: 8822B init table yhchuang
2019-01-30 4:02 ` [PATCH v4 11/13] rtw88: 8822C " yhchuang
2019-01-30 4:02 ` [PATCH v4 12/13] rtw88: Kconfig & Makefile yhchuang
2019-01-30 4:02 ` [PATCH v4 13/13] rtw88: add MAINTAINERS entry yhchuang
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