On Thu 14 May 07:39 PDT 2020, Shawn Guo wrote:
> Hi Bjorn,
>
> On Mon, May 11, 2020 at 10:52:42PM -0700, Bjorn Andersson wrote:
> > On Sat 09 May 06:08 PDT 2020, Shawn Guo wrote:
> >
> > > On some SoCs like MSM8939 with A405 adreno, there is a gfx_tbu clock
> > > needs to be on while doing TLB invalidate. Otherwise, TLBSYNC status
> > > will not be correctly reflected, causing the system to go into a bad
> > > state. Add it as an optional clock, so that platforms that have this
> > > clock can pass it over DT.
> > >
> > > Signed-off-by: Shawn Guo <[email protected]>
> > > ---
> > > drivers/iommu/qcom_iommu.c | 16 ++++++++++++++++
> > > 1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
> > > index 0e2a96467767..2f6c6da7d540 100644
> > > --- a/drivers/iommu/qcom_iommu.c
> > > +++ b/drivers/iommu/qcom_iommu.c
> > > @@ -45,6 +45,7 @@ struct qcom_iommu_dev {
> > > struct device *dev;
> > > struct clk *iface_clk;
> > > struct clk *bus_clk;
> > > + struct clk *tlb_clk;
> > > void __iomem *local_base;
> > > u32 sec_id;
> > > u8 num_ctxs;
> > > @@ -643,11 +644,20 @@ static int qcom_iommu_enable_clocks(struct
> > > qcom_iommu_dev *qcom_iommu)
> > > return ret;
> > > }
> > >
> > > + ret = clk_prepare_enable(qcom_iommu->tlb_clk);
> > > + if (ret) {
> > > + dev_err(qcom_iommu->dev, "Couldn't enable tlb_clk\n");
> > > + clk_disable_unprepare(qcom_iommu->bus_clk);
> > > + clk_disable_unprepare(qcom_iommu->iface_clk);
> > > + return ret;
> > > + }
> >
> > Seems this is an excellent opportunity to replace
> > qcom_iommu_enable_clocks() to clk_bulk_prepare_enable() and disable,
> > respectively.
>
> So we have two required and one optional clocks. I guess we don't want
> to use clk_bulk_get_optional() to get all of them as optional. So we
> will end up with getting clock with individual call and enabling/disabling
> with bulk version. I'm personally not fond of this mixed style. But if
> you really like this, I can change.
>
I share your dislike for mixing them, but I do prefer it over the nasty
error handling we end up with in qcom_iommu_enable_clocks().
Regards,
Bjorn
> >
> > > +
> > > return 0;
> > > }
> > >
> > > static void qcom_iommu_disable_clocks(struct qcom_iommu_dev *qcom_iommu)
> > > {
> > > + clk_disable_unprepare(qcom_iommu->tlb_clk);
> > > clk_disable_unprepare(qcom_iommu->bus_clk);
> > > clk_disable_unprepare(qcom_iommu->iface_clk);
> > > }
> > > @@ -839,6 +849,12 @@ static int qcom_iommu_device_probe(struct
> > > platform_device *pdev)
> > > return PTR_ERR(qcom_iommu->bus_clk);
> > > }
> > >
> > > + qcom_iommu->tlb_clk = devm_clk_get(dev, "tlb");
> >
> > Wouldn't "tbu" be a better name for this clock? Given that seems the
> > actually be the hardware block you're clocking.
>
> I was trying to emphasize the function of this clock. But I agree that
> 'tbu' is a better name now. I will change it in v2.
>
> Thanks for the comments.
>
> Shawn
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