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Message-ID: <ZPCbSse3J6ksZwJa@smile.fi.intel.com>
Date: Thu, 31 Aug 2023 16:53:14 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Stephen Boyd <swboyd@...omium.org>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>,
Hans de Goede <hdegoede@...hat.com>,
Mark Gross <markgross@...nel.org>,
linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
platform-driver-x86@...r.kernel.org,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
Prashant Malani <pmalani@...omium.org>
Subject: Re: [PATCH 1/3] platform/x86: intel_scu_ipc: Check status after
timeouts in busy_loop()
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))
>
> If this happens, then the status bit could change and this function
> would never test it again after checking the jiffies against the timeout
> limit. Polling code should check the condition one more time after the
> timeout in case this happens.
>
> The read_poll_timeout() helper implements this logic, and is shorter, so
> simply use that helper here.
I don't remember by heart, but on some older Intel hardware this might have
been called during early stages where ktime() is not functional yet.
Is this still a case here?
...
Codewise change looks good to me.
--
With Best Regards,
Andy Shevchenko
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