From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Stephen Boyd <swboyd@chromium.org>,
Hans de Goede <hdegoede@redhat.com>,
Mark Gross <markgross@kernel.org>,
linux-kernel@vger.kernel.org, patches@lists.linux.dev,
platform-driver-x86@vger.kernel.org,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Prashant Malani <pmalani@chromium.org>
Subject: Re: [PATCH 1/3] platform/x86: intel_scu_ipc: Check status after timeouts in busy_loop()
Date: Wed, 6 Sep 2023 17:31:47 +0300 [thread overview]
Message-ID: <20230906143147.GD1599918@black.fi.intel.com> (raw)
In-Reply-To: <ZPiCz6AaLc4mqGH8@smile.fi.intel.com>
On Wed, Sep 06, 2023 at 04:46:55PM +0300, Andy Shevchenko wrote:
> On Tue, Sep 05, 2023 at 05:27:23PM -0500, Stephen Boyd wrote:
> > Quoting Mika Westerberg (2023-08-31 22:50:11)
> > > On Wed, Aug 30, 2023 at 06:14:01PM -0700, Stephen Boyd wrote:
> > > > It's possible for the polling loop in busy_loop() to get scheduled away
> > > > for a long time.
> > > >
> > > > status = ipc_read_status(scu);
> > > > <long time scheduled away>
> > > > if (!(status & IPC_STATUS_BUSY))
> > >
> > > How can the status bit change here as we are the only user and the SCU
> > > access is serialized by ipclock?
> >
> > I don't know how the SCU works. I thought that IPC_STATUS_BUSY bit was
> > cleared by the SCU when it was done processing. With that assumption, I
> > tried to show that the status is read and then the process schedules
> > away for a long time and has an outdated view of the busy bit.
>
> We probably have different versions of firmwares for the different SoC
> generations. But I _think_ that you are right, the SCU firmware should
> clear the bit when it's done.
Yes, IIRC it does. Okay I see the (potential, although quite unlikely)
problem now. Thanks!
next prev parent reply other threads:[~2023-09-06 14:32 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 1:14 [PATCH 0/3] platform/x86: intel_scu_ipc: Timeout fixes Stephen Boyd
2023-08-31 1:14 ` [PATCH 1/3] platform/x86: intel_scu_ipc: Check status after timeouts in busy_loop() Stephen Boyd
2023-08-31 13:53 ` Andy Shevchenko
2023-09-05 22:24 ` Stephen Boyd
2023-09-06 13:58 ` Andy Shevchenko
2023-08-31 14:15 ` Kuppuswamy Sathyanarayanan
2023-09-01 5:50 ` Mika Westerberg
2023-09-05 22:27 ` Stephen Boyd
2023-09-06 13:46 ` Andy Shevchenko
2023-09-06 14:31 ` Mika Westerberg [this message]
2023-08-31 1:14 ` [PATCH 2/3] platform/x86: intel_scu_ipc: Check status upon timeout in ipc_wait_for_interrupt() Stephen Boyd
2023-08-31 13:58 ` Andy Shevchenko
2023-09-05 22:36 ` Stephen Boyd
2023-08-31 14:27 ` Kuppuswamy Sathyanarayanan
2023-09-05 22:56 ` Stephen Boyd
2023-09-01 6:04 ` Mika Westerberg
2023-08-31 1:14 ` [PATCH 3/3] platform/x86: intel_scu_ipc: Fail IPC send if still busy Stephen Boyd
2023-08-31 14:07 ` Andy Shevchenko
2023-09-01 6:06 ` Mika Westerberg
2023-09-05 22:42 ` Stephen Boyd
2023-08-31 3:28 ` [PATCH 0/3] platform/x86: intel_scu_ipc: Timeout fixes Kuppuswamy Sathyanarayanan
2023-09-05 22:55 ` Stephen Boyd
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