On Friday, January 27, 2017, Chris Brandt wrote:
> Due to the lack of clock status bits, we need to disable runtime pm
> for all RZ/A1 peripherals. Otherwise, it is possible that a driver
> will start using a peripheral before it is fully ready.
>
> By using pm_clk_resume immediately after we add the clock we ensure the
> usage counter will never get back down to 0, and hence will always keep
> the clock enabled.
>
> In order for dis_runtime_pm to be accessible for all relevant functions
> in this file, it needed to be a global.
>
> Signed-off-by: Chris Brandt <chris.brandt@xxxxxxxxxxx>
> ---
> drivers/clk/renesas/clk-mstp.c | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/renesas/clk-mstp.c b/drivers/clk/renesas/clk-
> mstp.c
> index 69cfdb9..3c91555 100644
> --- a/drivers/clk/renesas/clk-mstp.c
> +++ b/drivers/clk/renesas/clk-mstp.c
> @@ -59,6 +59,8 @@ struct mstp_clock {
> struct mstp_clock_group *group;
> };
>
> +static bool dis_runtime_pm;
> +
> #define to_mstp_clock(_hw) container_of(_hw, struct mstp_clock, hw)
>
> static inline u32 cpg_mstp_read(struct mstp_clock_group *group,
> @@ -216,6 +218,13 @@ static void __init cpg_mstp_clocks_init(struct
> device_node *np)
> if (of_device_is_compatible(np, "renesas,r7s72100-mstp-clocks"))
> group->width_8bit = true;
>
> + /*
> + * Due to the lack of clock status bits, we need to disable runtime
> pm
> + * for all RZ/A1 peripherals.
> + */
> + if (of_device_is_compatible(np, "renesas,r7s72100-mstp-clocks"))
> + dis_runtime_pm = true;
> +
> for (i = 0; i < MSTP_MAX_CLOCKS; ++i)
> clks[i] = ERR_PTR(-ENOENT);
>
> @@ -314,6 +323,9 @@ int cpg_mstp_attach_dev(struct generic_pm_domain
> *unused, struct device *dev)
> goto fail_destroy;
> }
>
> + if (dis_runtime_pm)
> + pm_clk_resume(dev);
> +
> return 0;
>
> fail_destroy:
> @@ -325,8 +337,11 @@ int cpg_mstp_attach_dev(struct generic_pm_domain
> *unused, struct device *dev)
>
> void cpg_mstp_detach_dev(struct generic_pm_domain *unused, struct device
> *dev)
> {
> - if (!list_empty(&dev->power.subsys_data->clock_list))
> + if (!list_empty(&dev->power.subsys_data->clock_list)) {
> + if (dis_runtime_pm)
> + pm_clk_suspend(dev);
> pm_clk_destroy(dev);
> + }
> }
>
> void __init cpg_mstp_add_clk_domain(struct device_node *np)
> @@ -344,7 +359,8 @@ void __init cpg_mstp_add_clk_domain(struct device_node
> *np)
> return;
>
> pd->name = np->name;
> - pd->flags = GENPD_FLAG_PM_CLK;
> + if (!dis_runtime_pm)
> + pd->flags = GENPD_FLAG_PM_CLK;
> pd->attach_dev = cpg_mstp_attach_dev;
> pd->detach_dev = cpg_mstp_detach_dev;
> pm_genpd_init(pd, &pm_domain_always_on_gov, false);
> --
> 2.10.1
>
Hmm, I might actually want to hold off on this one because I'm investigating
the individual drivers at the moment for flaws (I2C in particular)
-Chris
