Re: [PATCH 1/6] clk: qcom: gdsc: Add custom disable callback for GX GDSC

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 4/7/26 11:30 AM, Taniya Das wrote:
> From: Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>
> 
> The GX GDSC is a special power domain that should only be disabled
> by OS during GMU recovery. In all other scenarios, the GMU firmware
> is responsible for handling its disable sequence, and OS must not
> interfere.
> 
> During the resume_noirq() phase of system resume, the GenPD framework
> enables all power domains and later disables them in the complete()
> phase if there are no active votes from OS. This behavior can
> incorrectly disable the GX GDSC while the GMU firmware is still using
> it.
> 
> To prevent this, implement a custom disable callback for GX GDSC that
> relies on GenPD’s synced_poweroff flag. The GMU driver sets this flag
> only during recovery, allowing OS to explicitly disable GX GDSC in
> hardware in that case. In all other situations, the disable callback
> will avoid touching GX GDSC hardware.
> 
> Signed-off-by: Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>
> Signed-off-by: Taniya Das <taniya.das@oss.qualcomm.com>
> ---
>  drivers/clk/qcom/gdsc.c | 22 ++++++++++++++++++++++
>  drivers/clk/qcom/gdsc.h |  1 +
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 95aa071202455421d818171d04f95d15e2b581fa..ab5d741a2e2351bfac06a6814c5a8ba7355bc8bc 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -675,3 +675,25 @@ int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);
> +
> +/*
> + * GX GDSC is a special power domain. Normally, its disable sequence
> + * is managed by the GMU firmware, and high level OS must not attempt

nit: "and high level OS must not attempt" -> "and the OS must not attempt"


> + * to disable it. The only exception is during GMU recovery, where the
> + * GMU driver can set GenPD’s synced_poweroff flag to allow explicitly
> + * disable GX GDSC in hardware.
> + */
> +int gdsc_gx_disable(struct generic_pm_domain *domain)
> +{
> +	struct gdsc *sc = domain_to_gdsc(domain);
> +
> +	if (domain->synced_poweroff)
> +		return gdsc_disable(domain);

Can we use this version to replace gdsc_gx_do_nothing_enable() too?

Konrad