[PATCH] drm/msm/mdp5: enable clocks in hw_init and set_irqmask

[Rob Clark]

On Fri, Aug 28, 2015 at 3:56 AM, Archit Taneja <architt at codeaurora.org> wrote:
>
>
> On 08/27/2015 10:36 AM, Archit Taneja wrote:
>>
>>
>>
>> On 08/26/2015 08:42 PM, hali at codeaurora.org wrote:
>>>>
>>>> 2015-08-26 9:55 GMT-04:00  <hali at codeaurora.org>:
>>>>>
>>>>> Hi Archit,
>>>>>
>>>>>> mdp5_hw_init and mdp5_set_irqmask configure registers but may not have
>>>>>> clocks enabled.
>>>>>>
>>>>>> Add mdp5_enable/disable calls in these funcs to ensure clocks are
>>>>>> enabled. We need this until we get proper runtime pm support.
>>>>>>
>>>>>> Signed-off-by: Archit Taneja <architt at codeaurora.org>
>>>>>> ---
>>>>>>   drivers/gpu/drm/msm/mdp/mdp5/mdp5_irq.c | 10 ++++++++--
>>>>>>   drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c |  2 ++
>>>>>>   2 files changed, 10 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_irq.c
>>>>>> b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_irq.c
>>>>>> index b1f73be..9fabfca 100644
>>>>>> --- a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_irq.c
>>>>>> +++ b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_irq.c
>>>>>> @@ -24,9 +24,15 @@
>>>>>>   void mdp5_set_irqmask(struct mdp_kms *mdp_kms, uint32_t irqmask,
>>>>>>                uint32_t old_irqmask)
>>>>>>   {
>>>>>> -     mdp5_write(to_mdp5_kms(mdp_kms), REG_MDP5_MDP_INTR_CLEAR(0),
>>>>>> +     struct mdp5_kms *mdp5_kms = to_mdp5_kms(mdp_kms);
>>>>>> +
>>>>>> +     mdp5_enable(mdp5_kms);
>>>>>> +
>>>>>> +     mdp5_write(mdp5_kms, REG_MDP5_MDP_INTR_CLEAR(0),
>>>>>>                irqmask ^ (irqmask & old_irqmask));
>>>>>> -     mdp5_write(to_mdp5_kms(mdp_kms), REG_MDP5_MDP_INTR_EN(0),
>>>>>> irqmask);
>>>>>> +     mdp5_write(mdp5_kms, REG_MDP5_MDP_INTR_EN(0), irqmask);
>>>>>> +
>>>>>> +     mdp5_disable(mdp5_kms);
>>>>>>   }
>>>>>
>>>>>
>>>>> mdp5_set_irqmask() can be invoked in atomic context, clk_prepare() is
>>>>> not
>>>>> allowed in this function because it may cause process to sleep. We can
>>>>> enable the clocks in the caller at initialization.
>>
>>
>> Oh, oops. I missed that.
>>
>>>>
>>>> iirc, it will be called with at least one spinlock held..
>>>>
>>>> We do already move the enable/disable_vblank() paths off to a worker
>>>> so that we can ensure things are enabled before we get into
>>>> update_irq()..  the only other path to update_irq() should be when
>>>> driver code does mdp_irq_register/unregister().. so maybe we should
>>>> just require that the mdp4/mdp5 kms code only calls those when clk's
>>>> are already enabled (which should be mostly true already, I think)
>>>>
>>>> BR,
>>>> -R
>>>
>>>
>>> Yes, the only case that not been covered is mdp5_irq_postinstall(). We
>>> can
>>> enable clocks in this function. Actually, this is what we are doing in
>>> downstream test.
>>
>>
>> It works fine if I put it in postinstall. I'll update the patch and
>> resend.
>
>
> So, I hit an issue in both the approaches.
>
> When I try modeset, I get a watchdog reset once the app closes down.
>
> Looking at debug logs, it looks like the issue happens when the ioctl
> RMFB and drm_release race with each other.

hmm, this seems a bit strange.. since to do the RMFB ioctl the device
must still be open.. do we end up w/ the RMFB being an async commit
somehow?  (Although in case of flip w/ gpu rendering still pending,
somewhere we probably want to block on previous async commit?)

> Within the the msm driver, this maps to mdp5_complete_commit
> (drm_mode_rmfb path) being called before mdp5_crtc_cancel_pending_flip
> (drm_release path). mdp5_complete_commit disables clocks, and the other
> patch calls complete_flip, which requires clocks.
>
> If I wrap around complete_flip with mdp5_enable/disable calls, things
> work fine. Although, that's not an ideal fix.

I guess it is a reasonable thing to do.. but on that topic, it would
be nice if someone had some time to look and the pending atomic
suspend/resume/runtime-pm stuff.  I haven't really had time to follow
that, but I guess it is a good time to revisit the mdpN_enable/disable
stuff?

BR,
-R

> Any suggestions?
>
> Archit
>
>
> --
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