Re: [PATCH v16 2/5] iommu/arm-smmu: Invoke pm_runtime during probe, add/remove device

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Hi Vivek,

On 2018-09-25 6:56 AM, Vivek Gautam wrote:
Hi Robin, Will,

On Tue, Sep 18, 2018 at 8:41 AM Vivek Gautam
<vivek.gautam@xxxxxxxxxxxxxx> wrote:

Hi Robin,

On Fri, Sep 7, 2018 at 3:52 PM Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> wrote:

On Fri, Sep 7, 2018 at 3:22 PM Tomasz Figa <tfiga@xxxxxxxxxxxx> wrote:

On Fri, Sep 7, 2018 at 6:38 PM Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> wrote:

Hi Tomasz,


On 9/7/2018 2:46 PM, Tomasz Figa wrote:
Hi Vivek,

On Thu, Aug 30, 2018 at 11:46 PM Vivek Gautam
<vivek.gautam@xxxxxxxxxxxxxx> wrote:
From: Sricharan R <sricharan@xxxxxxxxxxxxxx>

The smmu device probe/remove and add/remove master device callbacks
gets called when the smmu is not linked to its master, that is without
the context of the master device. So calling runtime apis in those places
separately.
Global locks are also initialized before enabling runtime pm as the
runtime_resume() calls device_reset() which does tlb_sync_global()
that ultimately requires locks to be initialized.

Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
[vivek: Cleanup pm runtime calls]
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
   drivers/iommu/arm-smmu.c | 89 +++++++++++++++++++++++++++++++++++++++++++-----
   1 file changed, 81 insertions(+), 8 deletions(-)
[snip]
@@ -2215,10 +2281,17 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
          if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
                  dev_err(&pdev->dev, "removing device with active domains!\n");

+       arm_smmu_rpm_get(smmu);
          /* Turn the thing off */
          writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
+       arm_smmu_rpm_put(smmu);
+
+       if (pm_runtime_enabled(smmu->dev))
+               pm_runtime_force_suspend(smmu->dev);
+       else
+               clk_bulk_disable(smmu->num_clks, smmu->clks);

-       clk_bulk_disable_unprepare(smmu->num_clks, smmu->clks);
+       clk_bulk_unprepare(smmu->num_clks, smmu->clks);
Aren't we missing pm_runtime_disable() here? We'll have the enable
count unbalanced if the driver is removed and probed again.

pm_runtime_force_suspend() does a pm_runtime_disable() also if i am not
wrong.
And, as mentioned in a previous thread [1], we were seeing a warning
which we avoided
by keeping force_suspend().

[1] https://lkml.org/lkml/2018/7/8/124

I see, thanks. I didn't realize that pm_runtime_force_suspend()
already disables runtime PM indeed. Sorry for the noise.

Hi Tomasz,
No problem. Thanks for looking back at it.

Hi Robin,
If you are fine with this series, then can you please consider giving
Reviewed-by, so that we are certain that this series will go in the next merge
window.
Thanks

Gentle ping.
You ack will be very helpful in letting Will pull this series for 4.20.
Thanks.

I would really appreciate if you could provide your ack for this series.
Or if there are any concerns, I am willing to address them.

Apologies, I thought I'd replied to say I'd be getting to this shortly, but apparently not :(

FWIW, "shortly" is now tomorrow - I don't *think* there's anything outstanding, but given the number of subtleties we've turned up so far I do just want one last thorough double-check to make sure.

Thanks,
Robin.



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