Re: [PATCH 4/5] clk: qcom: videocc: Add support to attach multiple power domains

[Dmitry Baryshkov]

On Wed, Feb 19, 2025 at 05:08:52PM +0530, Jagadeesh Kona wrote:
> 
> 
> On 2/18/2025 10:49 PM, Dmitry Baryshkov wrote:
> > On Tue, Feb 18, 2025 at 03:46:15PM +0000, Bryan O'Donoghue wrote:
> >> On 18/02/2025 14:26, Jagadeesh Kona wrote:
> >>> During boot-up, the PLL configuration might be missed even after
> >>> calling pll_configure() from the clock controller probe. This can
> >>> happen because the PLL is connected to one or more rails that are
> >>> turned off, and the current clock controller code cannot enable
> >>> multiple rails during probe. Consequently, the PLL may be activated
> >>> with suboptimal settings, causing functional issues.
> >>>
> >>> To properly configure the video PLLs in the probe on SM8450, SM8475,
> >>> SM8550, and SM8650 platforms, the MXC rail must be ON along with MMCX.
> >>> Therefore, add support to attach multiple power domains to videocc on
> >>> these platforms.
> >>>
> >>> Signed-off-by: Jagadeesh Kona <quic_jkona@xxxxxxxxxxx>
> >>> ---
> >>>   drivers/clk/qcom/videocc-sm8450.c | 4 ++++
> >>>   drivers/clk/qcom/videocc-sm8550.c | 4 ++++
> >>>   2 files changed, 8 insertions(+)
> >>>
> >>> diff --git a/drivers/clk/qcom/videocc-sm8450.c b/drivers/clk/qcom/videocc-sm8450.c
> >>> index f26c7eccb62e7eb8dbd022e2f01fa496eb570b3f..b50a14547336580de88a741f1d33b126e9daa848 100644
> >>> --- a/drivers/clk/qcom/videocc-sm8450.c
> >>> +++ b/drivers/clk/qcom/videocc-sm8450.c
> >>> @@ -437,6 +437,10 @@ static int video_cc_sm8450_probe(struct platform_device *pdev)
> >>>   	struct regmap *regmap;
> >>>   	int ret;
> >>> +	ret = qcom_cc_attach_pds(&pdev->dev, &video_cc_sm8450_desc);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>>   	ret = devm_pm_runtime_enable(&pdev->dev);
> >>>   	if (ret)
> >>>   		return ret;
> >>> diff --git a/drivers/clk/qcom/videocc-sm8550.c b/drivers/clk/qcom/videocc-sm8550.c
> >>> index 7c25a50cfa970dff55d701cb24bc3aa5924ca12d..d4b223d1392f0721afd1b582ed35d5061294079e 100644
> >>> --- a/drivers/clk/qcom/videocc-sm8550.c
> >>> +++ b/drivers/clk/qcom/videocc-sm8550.c
> >>> @@ -542,6 +542,10 @@ static int video_cc_sm8550_probe(struct platform_device *pdev)
> >>>   	int ret;
> >>>   	u32 sleep_clk_offset = 0x8140;
> >>> +	ret = qcom_cc_attach_pds(&pdev->dev, &video_cc_sm8550_desc);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>>   	ret = devm_pm_runtime_enable(&pdev->dev);
> >>>   	if (ret)
> >>>   		return ret;
> >>>
> >>
> >> What's the difference between doing the attach here or doing it in
> >> really_probe() ?
> > 
> > I'd second this. If the domains are to be attached before calling any
> > other functions, move the call to the qcom_cc_map(), so that all drivers
> > get all domains attached before configuring PLLs instead of manually
> > calling the function.
> > 
> 
> I earlier tried moving the attach PDs call to qcom_cc_map(), but I faced the below issues
> 1. desc passed to qcom_cc_map() has const qualifier, so updating desc->pd_list
>    inside qcom_cc_map() is leading to a warning.

And? Can you fix the warning?

> 2. If we attach the PDs after calling get_sync() on device, I observed
>    that PDS are not getting enabled during probe. Currently qcom_cc_map()
>    is called after get_sync() is already called on device.

Move PM handling into qcom_cc_map(). Then together with the Bryan's
proposal most of the probe() functions can just call qcom_cc_probe()

> 
> Probably, we can add a new function qcom_cc_attach_pds_map() where we can
> attach PDs and call qcom_cc_map() inside it. We can then invoke this new
> function at the start of probe before get_sync(). I will post this change
> in next version if this aligns with your thoughts.
> 
> Thanks,
> Jagadeesh

-- 
With best wishes
Dmitry