linux-kernel - Re: [PATCH 2/7] clk: qcom: ipq8074: disable USB GDSC-s SW

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Message-ID: <YnSW+mNgAp17e/YE@builder.lan>
Date:   Thu, 5 May 2022 22:33:14 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Robert Marko <robimarko@...il.com>
Cc:     agross@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        absahu@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 2/7] clk: qcom: ipq8074: disable USB GDSC-s SW_COLLAPSE

On Mon 25 Apr 13:22 CDT 2022, Robert Marko wrote:

> Like in IPQ6018 Qualcomm intentionally disables the SW_COLLAPSE on the USB
> GDSC-s in the downstream 5.4 kernel.
> 
> This could potentially be better handled by utilizing the GDSC driver, but
> I am not familiar with it nor do I have datasheets.

Could you please give it a try before we pick this up?
Look at e.g. drivers/clk/qcom/gcc-sdm845.c how usb30_prim_gdsc and
usb30_sec_gdsc are defined, the offsets in specified in .gdscr should be
the same offsets you give below.

Then you specify an array of struct gdsc *, associating the two gdscs
you have specified to some identifier (USB30_PRIM_GDSC and
USB30_SEC_GDSC is used in sdm845) and reference this list as .gdscs and
num_gdscs in the gcc_ipq8074_desc.

The last part is to tie the USB controllers to the two GDSCs, this is
done by simply specifying:

	power-domains = <&gcc USB30_PRIM_GDSC>;

and USB30_SEC_GDSC, in the two USB nodes in DeviceTree. SW_COLLAPSE will
be toggled by the PM state of the USB driver, like it's done on e.g.
sdm845.

Regards,
Bjorn

> 
> Signed-off-by: Robert Marko <robimarko@...il.com>
> ---
>  drivers/clk/qcom/gcc-ipq8074.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gcc-ipq8074.c b/drivers/clk/qcom/gcc-ipq8074.c
> index 2ebd1462db78..65249a03a672 100644
> --- a/drivers/clk/qcom/gcc-ipq8074.c
> +++ b/drivers/clk/qcom/gcc-ipq8074.c
> @@ -4806,6 +4806,11 @@ static int gcc_ipq8074_probe(struct platform_device *pdev)
>  	if (IS_ERR(regmap))
>  		return PTR_ERR(regmap);
>  
> +	/* Disable SW_COLLAPSE for USB0 GDSCR */
> +	regmap_update_bits(regmap, 0x3e078, BIT(0), 0x0);
> +	/* Disable SW_COLLAPSE for USB1 GDSCR */
> +	regmap_update_bits(regmap, 0x3f078, BIT(0), 0x0);
> +
>  	clk_alpha_pll_configure(&ubi32_pll_main, regmap, &ubi32_pll_config);
>  	clk_alpha_pll_configure(&nss_crypto_pll_main, regmap,
>  				&nss_crypto_pll_config);
> -- 
> 2.35.1
>