linux-kernel - Re: [PATCH v2 2/3] clk: qcom: gcc-sc7180: Update the .pwrsts for usb gdsc

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Message-ID: <YyiOiudZuMDXOvGr@hovoldconsulting.com>
Date:   Mon, 19 Sep 2022 17:45:14 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Rajendra Nayak <quic_rjendra@...cinc.com>
Cc:     agross@...nel.org, andersson@...nel.org,
        konrad.dybcio@...ainline.org, mturquette@...libre.com,
        sboyd@...nel.org, mka@...omium.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, johan+linaro@...nel.org,
        quic_kriskura@...cinc.com, dianders@...omium.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 2/3] clk: qcom: gcc-sc7180: Update the .pwrsts for usb
 gdsc

On Fri, Sep 16, 2022 at 03:54:16PM +0530, Rajendra Nayak wrote:
> The USB controller on sc7180 does not retain the state when
> the system goes into low power state and the GDSC is
> turned off. This results in the controller reinitializing and
> re-enumerating all the connected devices (resulting in additional
> delay while coming out of suspend)
> Fix this by updating the .pwrsts for the USB GDSC so it only
> transitions to retention state in low power.
> 
> Signed-off-by: Rajendra Nayak <quic_rjendra@...cinc.com>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> Tested-by: Matthias Kaehlcke <mka@...omium.org>
> ---
> v2:
> Updated the changelog
> 
>  drivers/clk/qcom/gcc-sc7180.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/qcom/gcc-sc7180.c b/drivers/clk/qcom/gcc-sc7180.c
> index c2ea09945c47..2d3980251e78 100644
> --- a/drivers/clk/qcom/gcc-sc7180.c
> +++ b/drivers/clk/qcom/gcc-sc7180.c
> @@ -2224,7 +2224,7 @@ static struct gdsc usb30_prim_gdsc = {
>  	.pd = {
>  		.name = "usb30_prim_gdsc",
>  	},
> -	.pwrsts = PWRSTS_OFF_ON,
> +	.pwrsts = PWRSTS_RET_ON,
>  };
>  
>  static struct gdsc hlos1_vote_mmnoc_mmu_tbu_hf0_gdsc = {

It seems like the above will not work unless you also provide the
registers offsets that gdsc_force_mem_on() expects.

Specifically, unless you set cxc_count for the GDSC, the above call is a
no-op and the retention setting (i.e. the RETAIN_MEM and RETAIN_PERIPH
bits) will not be updated when registering the GDSC.

Johan