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.
> +
> 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.
That said, I thought we used device links and pm_runtime to ensure that
the TBUs are powered and clocked...
Regards,
Bjorn
> + if (IS_ERR(qcom_iommu->tlb_clk)) {
> + dev_dbg(dev, "failed to get tlb clock\n");
> + qcom_iommu->tlb_clk = NULL;
> + }
> +
> if (of_property_read_u32(dev->of_node, "qcom,iommu-secure-id",
> &qcom_iommu->sec_id)) {
> dev_err(dev, "missing qcom,iommu-secure-id property\n");
> --
> 2.17.1
>
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