Re: [PATCH v1 0/4] ACPI / LPSS: fix system hangup on BYT

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Fri, 2014-11-07 at 17:30 +0100, Rafael J. Wysocki wrote:
> On 11/7/2014 2:46 PM, Andy Shevchenko wrote:
> > On Fri, 2014-11-07 at 01:37 +0100, Rafael J. Wysocki wrote:
> >> On Wednesday, November 05, 2014 06:34:44 PM Andy Shevchenko wrote:
> >>> The Intel BayTrail based machines have different configuration of the Low Power
> >>> Sub System (LPSS) IP. The LPSS contains few host controllers, such as I2C, SPI,
> >>> I2C and common DMA IP to serve DMA transfers. Unfortunately the DMA IP has no
> >>> power control accessible for software / OS. It goes automatically down whenever
> >>> last device goes to sleep and turned on when one of them is turned on. When
> >>> user tries to access the powered off DMA device the system hangs.
> >>>
> >>> This patch series addressing the issue. Rafael suggested to create a 'proxy'
> >>> device which makes DMA to be powered on on the certain points of time.
> >>>
> >>> Vinod, we would like to push this via Rafael's tree, so, please Ack or NAck the
> >>> patch 4/4.
> >>>
> >>> Scott, do you have a chance to test this patch series against last linux-pm
> >>> tree on HP laptops? I would appreciate your Tested-by tag.
> >>>
> >>> Andy Shevchenko (4):
> >>>    ACPI / LPSS: add all LPSS devices to the specific power domain
> >>>    ACPI / LPSS: allow to use specific PM domain during ->probe()
> >>>    ACPI / LPSS: introduce a 'proxy' device to power on LPSS for DMA
> >>>    dmaengine: dw: enable runtime PM
> >> I'm essentially fine with this series, but I'm not sure what the status of
> >> the Scott's testing is.  Can you please tell me and Scott what in particular
> >> you wanted him to test?
> > He complained that HP laptop didn't reboot nicely and hangs the system
> > until he blacklisted dw_dmac driver.
> >
> 
> The patch series fixes runtime PM, though, so how is that related to 
> reboot exactly?

When he rebooted machine the dw_dmac driver was trying to access the HW
when LPSS is off (this is my understanding of the issue), thus, it was
stuck as long as he had dw_dmac loaded.

> 
> Rafael
> 


-- 
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy