linux-kernel - Re: [v2] PCI: tegra194: Fix debugfs directory creation when CONFIG

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Message-ID: <c51bbf38-0c6a-418f-b1e2-763d621186ff@wanadoo.fr>
Date: Sun, 6 Apr 2025 20:10:24 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: 18255117159@....com
Cc: bhelgaas@...gle.com, christophe.jaillet@...adoo.fr, jonathanh@...dia.com,
 kw@...ux.com, linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-tegra@...r.kernel.org, lpieralisi@...nel.org,
 manivannan.sadhasivam@...aro.org, robh@...nel.org, thierry.reding@...il.com
Subject: Re: [v2] PCI: tegra194: Fix debugfs directory creation when
 CONFIG_PCIEASPM is disabled

Le 06/04/2025 à 15:43, Hans Zhang a écrit :
> Previously, the debugfs directory was unconditionally created in
> tegra_pcie_config_rp() regardless of the CONFIG_PCIEASPM setting.
> This led to unnecessary directory creation when ASPM support was disabled.
> 
> Move the debugfs directory creation into init_debugfs() which is
> conditionally compiled based on CONFIG_PCIEASPM. This ensures:
> - The directory is only created when ASPM-related debugfs entries are
>    needed.
> - Proper error handling for directory creation failures.
> - Avoids cluttering debugfs with empty directories when ASPM is disabled.
> 
> Signed-off-by: Hans Zhang <18255117159-9Onoh4P/yGk@...lic.gmane.org>
> ---
> Changes since v1:
> https://lore.kernel.org/linux-pci/20250405145459.26800-1-18255117159-9Onoh4P/yGk@public.gmane.org
> 
> - The first version was committed incorrectly because the judgment
>    parameter in "debugfs_remove_recursive" was not noticed.
> ---
>   drivers/pci/controller/dwc/pcie-tegra194.c | 27 +++++++++++++---------
>   1 file changed, 16 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 5103995cd6c7..f048b2342af4 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -711,16 +711,27 @@ static void init_host_aspm(struct tegra_pcie_dw *pcie)
>   	dw_pcie_writel_dbi(pci, PCIE_PORT_AFR, val);
>   }
>   
> -static void init_debugfs(struct tegra_pcie_dw *pcie)
> +static int init_debugfs(struct tegra_pcie_dw *pcie)

I would keep it a void function.
If devm_kasprintf() fails, which is unlikely, then the module should 
still work correctly. So just a return; should be fine IMHO.

Usually, errors related to debugfs are silently ignored as is does not 
prevent this to work.

CJ

>   {
> -	debugfs_create_devm_seqfile(pcie->dev, "aspm_state_cnt", pcie->debugfs,
> +	struct device *dev = pcie->dev;
> +	char *name;
> +
> +	name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	pcie->debugfs = debugfs_create_dir(name, NULL);
> +
> +	debugfs_create_devm_seqfile(dev, "aspm_state_cnt", pcie->debugfs,
>   				    aspm_state_cnt);
> +
> +	return 0;
>   }
>   #else
>   static inline void disable_aspm_l12(struct tegra_pcie_dw *pcie) { return; }
>   static inline void disable_aspm_l11(struct tegra_pcie_dw *pcie) { return; }
>   static inline void init_host_aspm(struct tegra_pcie_dw *pcie) { return; }
> -static inline void init_debugfs(struct tegra_pcie_dw *pcie) { return; }
> +static inline int init_debugfs(struct tegra_pcie_dw *pcie) { return 0; }
>   #endif
>   
>   static void tegra_pcie_enable_system_interrupts(struct dw_pcie_rp *pp)
> @@ -1634,7 +1645,6 @@ static void tegra_pcie_deinit_controller(struct tegra_pcie_dw *pcie)
>   static int tegra_pcie_config_rp(struct tegra_pcie_dw *pcie)
>   {
>   	struct device *dev = pcie->dev;
> -	char *name;
>   	int ret;
>   
>   	pm_runtime_enable(dev);
> @@ -1664,14 +1674,9 @@ static int tegra_pcie_config_rp(struct tegra_pcie_dw *pcie)
>   		goto fail_host_init;
>   	}
>   
> -	name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
> -	if (!name) {
> -		ret = -ENOMEM;
> +	ret = init_debugfs(pcie);
> +	if (ret < 0)
>   		goto fail_host_init;
> -	}
> -
> -	pcie->debugfs = debugfs_create_dir(name, NULL);
> -	init_debugfs(pcie);
>   
>   	return ret;
>   
> 
> base-commit: a8662bcd2ff152bfbc751cab20f33053d74d0963