Re: [PATCH v5 17/17] i3c: renesas: Add runtime PM support

[Claudiu Beznea]

On 7/15/26 19:54, Frank Li wrote:
> On Mon, Jul 13, 2026 at 04:05:45PM +0300, Claudiu Beznea wrote:
> > From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> >
> > On the SoCs where the Renesas I3C driver is enabled (RZ/G3S and RZ/G3E),
> > the clocks of the IP are managed through a clock PM domain. To keep the
> > I3C code simpler, the explicit clock handling was dropped along with the
> > addition of runtime PM support, in favor of the runtime PM APIs. Only the
> > code for getting tclk was preserved, as it is necessary to compute the
> > I3C clock rate.
> >
> > All the APIs provided to the I3C subsystem through struct
> > i3c_master_controller_ops are guarded with runtime PM APIs to
> > enable/disable the controller at runtime.
> >
> > As the Renesas I3C driver implements an asynchronous transmit model by
> > preparing a transfer and waiting for its completion through the ISR,
> > renesas_i3c_abort_xfer() was added to disable interrupts and clear any
> > pending IRQ status bits when there is no completion in the defined
> > timeout. Along with this, renesas_i3c_wait_xfer() return type was changed
> > to unsigned long.
> >
> > Add runtime PM support for the Renesas I3C driver.
> >
> > Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v5:
> > - updated renesas_i3c_irqs_mask_and_clear() to use the
> >    renesas_i3c_irqs_mask_and_clear_locked() introduced in patch 1 from
> >    this series
> >
> > Changes in v4:
> > - renamed renesas_i3c_abort_xfer() from v3 to
> >    renesas_i3c_irqs_mask_and_clear(); along with it renamed local varibles
> >    abort_xfer to xfer_failed
> >
> > Changes in v3:
> > - dropped the RPM resume/suspend in renesas_i3c_suspend() to read the
> >    DATBASn registers as the DATBASn register are not used on suspend/resume
> >    path anymore in this version
> >
> > Changes in v2:
> > - dropped the runtime suspend/resume functions as for now, there will be
> >    no pinctrl sleep state described in DT
> > - do not synchronize the IRQs in renesas_i3c_abort_xfer() as some handlers
> >    may re-enable interrupts; instead just disable the interrupts and clean
> >    any status bits that the IRQ handlers are touching; with this the
> >    struct renesas_i3c::{irqs, num_irqs} and the associated code was removed
> > - dropped the renesas_i3c_dont_use_autosuspend() along with the
> >    devm_add_action_or_reset() call to set it since the same operation is
> >    done by the devres cleanup helper of devm_pm_runtime_enable()
> > - adjusted the renesas_i3c_suspend() with RPM calls to save the DATBAS
> >    registers
> > - use pm_runtime_resume_and_get() in renesas_i3c_resume() to avoid
> >    mixing gotos with cleanup helpers
> > - adjusted the patch description to reflect these changes
> ...
> > @@ -1384,12 +1458,16 @@ static int renesas_i3c_probe(struct platform_device *pdev)
> >   	if (IS_ERR(i3c->regs))
> >   		return PTR_ERR(i3c->regs);
> >
> > -	ret = devm_clk_bulk_get_all_enabled(&pdev->dev, &i3c->clks);
> > -	if (ret <= RENESAS_I3C_TCLK_IDX)
> > -		return dev_err_probe(&pdev->dev, ret < 0 ? ret : -EINVAL,
> > -				     "Failed to get clocks (need > %d, got %d)\n",
> > -				     RENESAS_I3C_TCLK_IDX, ret);
> > -	i3c->num_clks = ret;
> > +	i3c->tclk = devm_clk_get(&pdev->dev, "tclk");
>
> only one tclk? you remove devm_clk_bulk_get_all_enabled()
On all the SoCs where this driver is used the clocks are managed through clock 
PM domains. The clock PM domain registration is done though the drivers at [1] 
or [2].

The genpd registered by those drivers are passing GENPD_FLAG_PM_CLK flag to the
pm_genpd_init(). In that case the start/stop APIs of the genpd are
pm_clk_suspend/pm_clk_resume [3].

Thus, we can make use of runtime PM APIs to request, enable, disable the clocks 
using generic runtime PM APIs.

Every time this driver calls runtime suspend/resume APIs this goes down to the 
IP clocks and clk_disable()/clk_enable() them.

Since we are relying on clock PM domains there is no need to implement runtime 
suspend/resume ops for this driver that does just only 
clock_disable()/clk_enable(), thus, the final code is simpler. We only request 
the tclk as we need to compute the bus rate based on it.

Thank you,
Claudiu

[1]
https://elixir.bootlin.com/linux/v7.1-rc3/source/drivers/clk/renesas/rzg2l-cpg.c#L2013
[2]
https://elixir.bootlin.com/linux/v7.1-rc3/source/drivers/clk/renesas/rzv2h-cpg.c#L1549
[3] https://elixir.bootlin.com/linux/v7.1-rc3/source/drivers/pmdomain/core.c#L2439