[PATCH v3 12/33] iommu/mediatek: Always tlb_flush_all when each PM resume

[Yong Wu]

On Sat, 2021-11-27 at 12:11 +0200, Dafna Hirschfeld wrote:
> 
> On 10.11.21 09:50, Yong Wu wrote:
> > On Wed, 2021-11-10 at 07:29 +0200, Dafna Hirschfeld wrote:
> > > 
> > > On 10.11.21 04:20, Yong Wu wrote:
> > > > On Tue, 2021-11-09 at 14:21 +0200, Dafna Hirschfeld wrote:
> > > > > Hi
> > > > > This patch is needed in order to update the tlb when a device
> > > > > is
> > > > > powered on.
> > > > > Could you send this patch alone without the whole series so
> > > > > it
> > > > > get
> > > > > accepted easier?
> > > > 
> > > > Which SoC are you testing on? In previous SoC, the IOMMU HW
> > > > don't
> > > > have
> > > > power-domain, and we have a "has_pm"[1] in the tlb function for
> > > > that
> > > > case. The "has_pm" should be always 0 for the previous SoC like
> > > > mt8173,
> > > > it should always tlb synchronize.
> > > > 
> > > > thus, Could you help share more about your issue? In which case
> > > > it
> > > > lack
> > > > the necessary tlb operation. At least, We need confirm if it
> > > > needs
> > > > a
> > > > "Fixes" tags if sending this patch alone.
> > > 
> > > Hi,
> > > I work with the mtk-vcodec driver on mt8173. As you wrote, the
> > > iommu
> > > doesn't
> > > have a power-domain and so when allocating buffers before the
> > > device
> > > is powered
> > > on, there is the warning
> > > "Partial TLB flush timed out, falling back to full flush"
> > > flooding the log buf.
> > 
> > oh. Thanks very much for your information. Get it now.
> > 
> > This issue should be introduced by the:
> > 
> > b34ea31fe013 ("iommu/mediatek: Always enable the clk on resume")
> 
> Hi, reverting this commit didn't solve those warnings,
> I think this is because in the function mtk_iommu_attach_device
> the first call to pm_runtime_resume_and_get does not turn the clks on
> since m4u_dom is not yet initialize. And then mtk_iommu_attach_device
> calls pm_runtime_put right after mtk_iommu_hw_init is called
> (where the clks are turned on)

oh. Right. this is also related with the patch of "Add power-domain
operation".

The current problem is that there is a redundant log of "Partial TLB
flush timed out" in mt8173. We need fix this issue firstly. Are you
going to prepare the patches again? If not, I could help this. You
could help confirm them if you are free.

Thanks.

> 
> thanks,
> Dafna
> 
> 
> > 
> > tlb failed due to the bclk is not enabled. Could you help try that
> > after reverting this?
> > 
> > > 
> > > Sebastian Reichel suggested to remove the 'if(has_pm)' check to
> > > avoid
> > > this warning,
> > > and avoid flushing the tlb if the device is off:
> > > 
> > > [1] http://ix.io/3Eyr
> > > 
> > > This fixes the warning, but then the tlb is not flushed in sync,
> > > Therefore the tlb should be flushed when the device is resumed.
> > > 
> > > So the two patches (the one suggested in the link [1] and this
> > > patch)
> > > should be sent together as a 2-patch series.
> > 
> > then this is reasonable. You could help this into a new patchset if
> > you
> > are free(add Fixes tag).
> > 
> > Thanks.
> > 
> > > 
> > > Thanks,
> > > Dafna
> > >