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

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Message-ID: <c0582215-e09e-44f7-a225-7c255e26d29f@163.com>
Date: Mon, 7 Apr 2025 09:16:33 +0800
From: Hans Zhang <18255117159@....com>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: bhelgaas@...gle.com, 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



On 2025/4/7 02:10, Christophe JAILLET wrote:
> 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.
> 

Hi Christophe,

Thanks your for reply. Will change.

Best regards,
Hans

> 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