linux-kernel - Re: [PATCH v5 04/12] PCI: brcmstb: Use bridge reset if available

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Message-ID: <9c22a495-7b89-4df6-b57b-cb0f39b09c30@suse.de>
Date: Fri, 9 Aug 2024 14:16:09 +0300
From: Stanimir Varbanov <svarbanov@...e.de>
To: Jim Quinlan <james.quinlan@...adcom.com>, linux-pci@...r.kernel.org,
 Nicolas Saenz Julienne <nsaenz@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>,
 Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
 Cyril Brulebois <kibi@...ian.org>, Stanimir Varbanov <svarbanov@...e.de>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Krzysztof Kozlowski <krzk@...nel.org>,
 bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Rob Herring <robh@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>,
 "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
 <linux-rpi-kernel@...ts.infradead.org>,
 "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE"
 <linux-arm-kernel@...ts.infradead.org>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 04/12] PCI: brcmstb: Use bridge reset if available

Hi Jim,

On 8/1/24 01:28, Jim Quinlan wrote:
> The 7712 SOC has a bridge reset which can be described in the device tree.
> Use it if present.  Otherwise, continue to use the legacy method to reset
> the bridge.
> 
> Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> ---
>  drivers/pci/controller/pcie-brcmstb.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index 7595e7009192..4d68fe318178 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -265,6 +265,7 @@ struct brcm_pcie {
>  	enum pcie_type		type;
>  	struct reset_control	*rescal;
>  	struct reset_control	*perst_reset;
> +	struct reset_control	*bridge_reset;
>  	int			num_memc;
>  	u64			memc_size[PCIE_BRCM_MAX_MEMC];
>  	u32			hw_rev;
> @@ -732,12 +733,19 @@ static void __iomem *brcm7425_pcie_map_bus(struct pci_bus *bus,
>  
>  static void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie, u32 val)
>  {
> -	u32 tmp, mask =  RGR1_SW_INIT_1_INIT_GENERIC_MASK;
> -	u32 shift = RGR1_SW_INIT_1_INIT_GENERIC_SHIFT;
> +	if (val)
> +		reset_control_assert(pcie->bridge_reset);
> +	else
> +		reset_control_deassert(pcie->bridge_reset);
>  
> -	tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
> -	tmp = (tmp & ~mask) | ((val << shift) & mask);
> -	writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
> +	if (!pcie->bridge_reset) {
> +		u32 tmp, mask =  RGR1_SW_INIT_1_INIT_GENERIC_MASK;
> +		u32 shift = RGR1_SW_INIT_1_INIT_GENERIC_SHIFT;
> +
> +		tmp = readl(pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
> +		tmp = (tmp & ~mask) | ((val << shift) & mask);
> +		writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
> +	}
>  }
>  
>  static void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32 val)
> @@ -1621,10 +1629,16 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  	if (IS_ERR(pcie->perst_reset))
>  		return PTR_ERR(pcie->perst_reset);
>  
> +	pcie->bridge_reset = devm_reset_control_get_optional_exclusive(&pdev->dev, "bridge");

Shouldn't this be devm_reset_control_get_optional_shared? See more below.

> +	if (IS_ERR(pcie->bridge_reset))
> +		return PTR_ERR(pcie->bridge_reset);
> +
>  	ret = clk_prepare_enable(pcie->clk);
>  	if (ret)
>  		return dev_err_probe(&pdev->dev, ret, "could not enable clock\n");
>  
> +	pcie->bridge_sw_init_set(pcie, 0);

According to reset_control_get_shared description looks like this
.deassert is satisfying the requirements for _shared reset-control API
variant.
Is that the intention to call reset_control_deassert() here?

> +
>  	ret = reset_control_reset(pcie->rescal);
>  	if (dev_err_probe(&pdev->dev, ret, "failed to deassert 'rescal'\n"))
>  		goto clk_disable_unprepare;

~Stan