linux-kernel - Re: [PATCH 3/4] soc: mediatek: add support of MTK_SCPD_STRICT

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Message-ID: <bfe13669-0b22-2b50-12df-e37095faf62c@wanadoo.fr>
Date:   Tue, 31 May 2022 19:17:08 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Fabien Parent <fparent@...libre.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Alexandre Bailon <abailon@...libre.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] soc: mediatek: add support of MTK_SCPD_STRICT_BUSP
 cap

Le 30/05/2022 à 22:42, Fabien Parent a écrit :
> From: Alexandre Bailon <abailon@...libre.com>
> 
> This adds support of MTK_SCPD_STRICT_BUSP cap.
> This is required by the mt8365, for the MM power domain.
> 
> Signed-off-by: Alexandre Bailon <abailon@...libre.com>
> Signed-off-by: Fabien Parent <fparent@...libre.com>
> ---
>   drivers/soc/mediatek/mtk-pm-domains.c | 37 ++++++++++++++++++++-------
>   drivers/soc/mediatek/mtk-pm-domains.h |  1 +
>   2 files changed, 29 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
> index 90b91b3b19a8..beaa5785fda2 100644
> --- a/drivers/soc/mediatek/mtk-pm-domains.c
> +++ b/drivers/soc/mediatek/mtk-pm-domains.c
> @@ -263,17 +263,36 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
>   	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ISO_BIT);
>   	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
>   
> -	ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
> -	if (ret)
> -		goto err_pwr_ack;
> +	if (MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUSP)) {
> +		/*
> +		 * In few Mediatek platforms(e.g. MT6779), the bus protect
> +		 * policy is stricter, which leads to bus protect release must
> +		 * be prior to bus access.
> +		 */
> +		ret = scpsys_sram_enable(pd);
> +		if (ret < 0)
> +			goto err_pwr_ack;

Hi,
with this new path, the error handling path looks odd because the order 
of operation is not the same.

>   
> -	ret = scpsys_sram_enable(pd);
> -	if (ret < 0)
> -		goto err_disable_subsys_clks;
> +		ret = scpsys_bus_protect_disable(pd);
> +		if (ret < 0)
> +			goto err_pwr_ack;

Here...

>   
> -	ret = scpsys_bus_protect_disable(pd);
> -	if (ret < 0)
> -		goto err_disable_sram;
> +		ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
> +		if (ret < 0)
> +			goto err_pwr_ack;

... and here as well.

CJ

> +	} else {
> +		ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
> +		if (ret)
> +			goto err_pwr_ack;
> +
> +		ret = scpsys_sram_enable(pd);
> +		if (ret < 0)
> +			goto err_disable_subsys_clks;
> +
> +		ret = scpsys_bus_protect_disable(pd);
> +		if (ret < 0)
> +			goto err_disable_sram;
> +	}
>   
>   	return 0;
>   
> diff --git a/drivers/soc/mediatek/mtk-pm-domains.h b/drivers/soc/mediatek/mtk-pm-domains.h
> index a3955d960233..5347471bc3c4 100644
> --- a/drivers/soc/mediatek/mtk-pm-domains.h
> +++ b/drivers/soc/mediatek/mtk-pm-domains.h
> @@ -8,6 +8,7 @@
>   #define MTK_SCPD_SRAM_ISO		BIT(2)
>   #define MTK_SCPD_KEEP_DEFAULT_OFF	BIT(3)
>   #define MTK_SCPD_DOMAIN_SUPPLY		BIT(4)
> +#define MTK_SCPD_STRICT_BUSP		BIT(5)
>   #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
>   
>   #define SPM_VDE_PWR_CON			0x0210