Boot hang regression 3.10.0-rc4 -> 3.10.0

[Rajendra Nayak]

On Tuesday 16 July 2013 12:53 AM, Suman Anna wrote:
> On 07/15/2013 05:01 AM, Rajendra Nayak wrote:
>> On Monday 15 July 2013 12:14 PM, Rajendra Nayak wrote:
>>> On Friday 12 July 2013 06:10 AM, Suman Anna wrote:
>>>> On 07/11/2013 04:59 AM, Grygorii Strashko wrote:
>>>>> Hi,
>>>>>
>>>>> On 07/11/2013 09:32 AM, Tony Lindgren wrote:
>>>>>> * Felipe Balbi <balbi at ti.com> [130710 09:18]:
>>>>>>>
>>>>>>> On Wed, Jul 10, 2013 at 07:07:04PM +0300, Felipe Balbi wrote:
>>>>>>>> how about something like below ? It makes omap_device/hwmod and
>>>>>>>> pm_runtime agree on the initial state of the device and will prevent
>>>>>>>> ->runtime_resume() from being called on first pm_runtime_get*() done
>>>>>>>> during probe.
>>>>>>>>
>>>>>>>> This is similar to what PCI bus does (if you look at pci_pm_init()).
>>>>>>>>
>>>>>>>> commit 59108a500b4ab4b1a5102648a3360276dbf7df6f
>>>>>>>> Author: Felipe Balbi <balbi at ti.com>
>>>>>>>> Date:   Wed Jul 10 18:50:16 2013 +0300
>>>>>>>>
>>>>>>>>      arm: omap2plus: unidle devices which are about to probe
>>>>>>>>
>>>>>>>>      in order to make HWMOD and pm_runtime agree on the
>>>>>>>>      initial state of the device, we will unidle the device
>>>>>>>>      and call pm_runtime_set_active() to tell pm_runtime
>>>>>>>>      that the device is really active.
>>>>> Don't think that it's good idea (
>>>>> I've checked some driver's and think this patch will enable some devices
>>>>> unpredictably:
>>>>> - hwspinlock
>>>>> - mailbox
>>>>> - iommu
>>>>> - ipu
>>>>> All above devices need to be enabled on demand only (no
>>>>> pm_runtime_get*() calls in probe). More over, some of them have very
>>>>> specific enabling sequence - like ipu).
>>>>>
>>>>> May be Summan can say more on that.
>>>>
>>>> Indeed, this is a problem for any of the slave processor devices.
>>>> mailbox and iommu would be slaves to the remoteproc and the drivers have
>>>> a specific sequence of bringing up a processor. The current
>>>> hwmod/omap_device code is such that these devices will be left in reset
>>>> and the driver code use the omap_device_(de)assert_hardreset API
>>>> together with omap_device_enable code to bring up the devices. The
>>>> remoteproc driver also needs to assert the resets (there are other
>>>> problems associated with using omap_device_idle for remoteproc and
>>>> iommu) for bringing up the devices after a suspend sequence. hwspinlock
>>>> and mailbox may get away since they are in CORE domain, but definitely
>>>> an issue for iommu and remoteproc. I would think that this would also
>>>> affect other compute devices like IVAHD, ISS, SGX.
>>>
>>> Today, for these IPs I guess hwmod waits for the resets to be de-asserted, right?
> 
> Yes, the omap_device_enable bails out if the reset lines are still
> asserted, and the driver code deals with the resets currently. This code
> essentially achieves the same as if a HWMOD_INIT_NO_RESET flag is
> added to the corresponding hwmods - we do not want the hwmod/omap_device
> code to enable the processor IPs and leave the enabling/device
> management to the driver.
> 
>>>
>>>         /*
>>>          * If an IP block contains HW reset lines and all of them are
>>>          * asserted, we let integration code associated with that
>>>          * block handle the enable.  We've received very little
>>>          * information on what those driver authors need, and until
>>>          * detailed information is provided and the driver code is
>>>          * posted to the public lists, this is probably the best we
>>>          * can do.
>>>          */
>>>         if (_are_all_hardreset_lines_asserted(oh))
>>>                 return 0;
>>>
>>> What if this information is send back to omap_device() through a return value
>>> so omap_device() knows about this too, so it avoids marking the omap device as
>>> enabled? Wouldn't that fix the issue?
>>
>> I meant something like this..
>>
>> From 2fbea0dde0f72897089ef2e8e441b5e5bd6ea967 Mon Sep 17 00:00:00 2001
>> From: Rajendra Nayak <rnayak at ti.com>
>> Date: Mon, 15 Jul 2013 15:23:07 +0530
>> Subject: [PATCH] ARM: OMAP2+: Make omap_device aware of hwmod failing to
>>  enable/idle/shutdown the hwmods
>>
>> For IP blocks (mainly processors) which have hard reset lines, hwmod avoids
>> enable/idle/shutdown operations as long as all the hard reset lines are
>> kept asserted. However it does not return an error back to the caller (in some
>> cases the omap_device layer) to communicate back the failure to operate on the
>> hwmod.
>>
>> Fix this by making _enable()/_idle()/_shutdown() all return an error in such
>> cases, and also fix the omap_device layer to look at the return values coming
>> from hwmod operations before doing a omap_device level state transition.
>>
>> Signed-off-by: Rajendra Nayak <rnayak at ti.com>
> 
> Let me test this and get back to you if there are any issues.

Great, thanks for testing.

> 
> regards
> Suman
>