Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 11 Jul 2023 11:50:03 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Tinghan Shen <tinghan.shen@mediatek.com>
Cc:     Bjorn Andersson <andersson@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-remoteproc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com
Subject: Re: [PATCH v14 07/12] remoteproc: mediatek: Remove dependency of
 MT8195 SCP L2TCM power control on dual-core SCP
Message-ID: <ZK2WS+cldx/8+VGA@p14s>
References: <20230707052612.27521-1-tinghan.shen@mediatek.com>
 <20230707052612.27521-8-tinghan.shen@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230707052612.27521-8-tinghan.shen@mediatek.com>
Precedence: bulk

On Fri, Jul 07, 2023 at 01:26:07PM +0800, Tinghan Shen wrote:
> Previously, SCP core 0 controlled the power of L2TCM and dictated that
> SCP core 1 could only boot after SCP core 0. To address this constraint,
> extracted the power control flow of L2TCM and made it shared
> between both cores, enabling support of arbitrary boot order.

Definitely an improvement.

> 
> The flow for controlling L2TCM power has been incorporated into the
> mt8195_scp_before_load() and mt8195_scp_stop() APIs, which are
> respectively invoked during the rproc->ops->start() and
> rproc->ops->stop() operations. These APIs effectively serve the same
> purpose as the rproc prepare()/unprepare() APIs."

I'm not fond of that custom API but it is so widespread in this driver that I
will go with it.

> 
> Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
> ---
>  drivers/remoteproc/mtk_common.h |  1 +
>  drivers/remoteproc/mtk_scp.c    | 80 ++++++++++++++++++++++++++-------
>  2 files changed, 66 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/remoteproc/mtk_common.h b/drivers/remoteproc/mtk_common.h
> index 56395e8664cb..41e1b4732b75 100644
> --- a/drivers/remoteproc/mtk_common.h
> +++ b/drivers/remoteproc/mtk_common.h
> @@ -130,6 +130,7 @@ struct mtk_scp {
>  	struct rproc_subdev *rpmsg_subdev;
>  
>  	struct list_head elem;
> +	struct platform_device *cluster_pdev;

This isn't needed.  rproc->dev.parent is pdev->dev.  Use container_of() to
get to the platform device. 


>  };
>  
>  /**
> diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> index 3349488e5f21..94602272c05f 100644
> --- a/drivers/remoteproc/mtk_scp.c
> +++ b/drivers/remoteproc/mtk_scp.c
> @@ -29,6 +29,10 @@ struct mtk_scp_of_cluster {
>  	size_t l1tcm_size;
>  	phys_addr_t l1tcm_phys;
>  	struct list_head mtk_scp_list;
> +
> +	/* Prevent concurrent operations of L2TCM power control. */
> +	struct mutex l2tcm_lock;
> +	u32 l2tcm_refcnt;
>  };
>  
>  /**
> @@ -449,7 +453,7 @@ static int mt8192_scp_before_load(struct mtk_scp *scp)
>  
>  	writel(1, scp->reg_base + MT8192_CORE0_SW_RSTN_SET);
>  
> -	/* enable SRAM clock */
> +	/* enable SRAM power */
>  	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_0, 0);
>  	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
>  	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_2, 0);
> @@ -462,19 +466,38 @@ static int mt8192_scp_before_load(struct mtk_scp *scp)
>  	return 0;
>  }
>  
> -static int mt8195_scp_before_load(struct mtk_scp *scp)
> +static int mt8195_scp_l2tcm_on(struct mtk_scp *scp)
>  {
> -	/* clear SPM interrupt, SCP2SPM_IPC_CLR */
> -	writel(0xff, scp->reg_base + MT8192_SCP2SPM_IPC_CLR);
> +	struct mtk_scp_of_cluster *scp_cluster = platform_get_drvdata(scp->cluster_pdev);
> +
> +	mutex_lock(&scp_cluster->l2tcm_lock);
> +
> +	if (scp_cluster->l2tcm_refcnt == 0) {
> +		/* clear SPM interrupt, SCP2SPM_IPC_CLR */
> +		writel(0xff, scp->reg_base + MT8192_SCP2SPM_IPC_CLR);
> +
> +		/* Power on L2TCM */
> +		scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_0, 0);
> +		scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
> +		scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_2, 0);
> +		scp_sram_power_on(scp->reg_base + MT8192_L1TCM_SRAM_PDN,
> +				  MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS);
> +	}
> +
> +	scp_cluster->l2tcm_refcnt += 1;
>  
> +	mutex_unlock(&scp_cluster->l2tcm_lock);
> +
> +	return 0;
> +}
> +
> +static int mt8195_scp_before_load(struct mtk_scp *scp)
> +{
>  	writel(1, scp->reg_base + MT8192_CORE0_SW_RSTN_SET);
>  
> +	mt8195_scp_l2tcm_on(scp);
> +
>  	/* enable SRAM clock */
> -	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_0, 0);
> -	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
> -	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_2, 0);
> -	scp_sram_power_on(scp->reg_base + MT8192_L1TCM_SRAM_PDN,
> -			  MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS);
>  	scp_sram_power_on(scp->reg_base + MT8192_CPU0_SRAM_PD, 0);
>  
>  	/* enable MPU for all memory regions */
> @@ -487,6 +510,8 @@ static int mt8195_scp_c1_before_load(struct mtk_scp *scp)
>  {
>  	scp->data->scp_reset_assert(scp);
>  
> +	mt8195_scp_l2tcm_on(scp);
> +
>  	scp_sram_power_on(scp->reg_base + MT8195_CPU1_SRAM_PD, 0);
>  
>  	/* enable MPU for all memory regions */
> @@ -653,14 +678,30 @@ static void mt8192_scp_stop(struct mtk_scp *scp)
>  	writel(0, scp->reg_base + MT8192_CORE0_WDT_CFG);
>  }
>  
> +static void mt8195_scp_l2tcm_off(struct mtk_scp *scp)
> +{
> +	struct mtk_scp_of_cluster *scp_cluster = platform_get_drvdata(scp->cluster_pdev);
> +
> +	mutex_lock(&scp_cluster->l2tcm_lock);
> +

What happens if ->l2tcm_refcnt is 0 and this function is called?


> +	scp_cluster->l2tcm_refcnt -= 1;
> +
> +	if (scp_cluster->l2tcm_refcnt == 0) {
> +		/* Power off L2TCM */
> +		scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_0, 0);
> +		scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
> +		scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_2, 0);
> +		scp_sram_power_off(scp->reg_base + MT8192_L1TCM_SRAM_PDN, 0);
> +		scp_sram_power_off(scp->reg_base + MT8192_CPU0_SRAM_PD, 0);
> +	}
> +
> +	mutex_unlock(&scp_cluster->l2tcm_lock);
> +}
> +
>  static void mt8195_scp_stop(struct mtk_scp *scp)
>  {
> -	/* Disable SRAM clock */
> -	scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_0, 0);
> -	scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
> -	scp_sram_power_off(scp->reg_base + MT8192_L2TCM_SRAM_PD_2, 0);
> -	scp_sram_power_off(scp->reg_base + MT8192_L1TCM_SRAM_PDN,
> -			   MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS);
> +	mt8195_scp_l2tcm_off(scp);
> +
>  	scp_sram_power_off(scp->reg_base + MT8192_CPU0_SRAM_PD, 0);
>  
>  	/* Disable SCP watchdog */
> @@ -669,6 +710,8 @@ static void mt8195_scp_stop(struct mtk_scp *scp)
>  
>  static void mt8195_scp_c1_stop(struct mtk_scp *scp)
>  {
> +	mt8195_scp_l2tcm_off(scp);
> +
>  	/* Power off CPU SRAM */
>  	scp_sram_power_off(scp->reg_base + MT8195_CPU1_SRAM_PD, 0);
>  
> @@ -976,6 +1019,8 @@ static int scp_add_single_core(struct platform_device *pdev)
>  	if (IS_ERR(scp))
>  		return PTR_ERR(scp);
>  
> +	scp->cluster_pdev = pdev;
> +
>  	ret = rproc_add(scp->rproc);
>  	if (ret) {
>  		dev_err(dev, "Failed to add rproc\n");
> @@ -1028,6 +1073,8 @@ static int scp_add_multi_core(struct platform_device *pdev)
>  			goto init_fail;
>  		}
>  
> +		scp->cluster_pdev = pdev;
> +
>  		ret = rproc_add(scp->rproc);
>  		if (ret) {
>  			dev_err(dev, "Failed to add rproc of core %d\n", core_id);
> @@ -1114,6 +1161,7 @@ static int scp_probe(struct platform_device *pdev)
>  	}
>  
>  	INIT_LIST_HEAD(&scp_cluster->mtk_scp_list);
> +	mutex_init(&scp_cluster->l2tcm_lock);
>  	platform_set_drvdata(pdev, scp_cluster);
>  
>  	ret = devm_of_platform_populate(dev);
> @@ -1137,6 +1185,8 @@ static void scp_remove(struct platform_device *pdev)
>  		rproc_del(scp->rproc);
>  		scp_free(scp);
>  	}
> +
> +	mutex_destroy(&scp_cluster->l2tcm_lock);
>  }
>  
>  static const struct mtk_scp_of_data mt8183_of_data = {
> -- 
> 2.18.0
>