Re: [PATCH v14 07/12] remoteproc: mediatek: Remove dependency of MT8195 SCP L2TCM power control on dual-core SCP

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
Date: Tue, 11 Jul 2023 12:00:10 -0600	[thread overview]
Message-ID: <ZK2YqtlMPWdQzG0l@p14s> (raw)
In-Reply-To: <ZK2WS+cldx/8+VGA@p14s>

On Tue, Jul 11, 2023 at 11:50:03AM -0600, Mathieu Poirier wrote:
> 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?
>

More comments to come tomorrow.

Thanks,
Mathieu

> 
> > +	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
> > 