Re: [v2] PCI: dwc: Add the debugfs property to provide the LTSSM status of the PCIe link

[Niklas Cassel <cassel@kernel.org>]

On Thu, Feb 06, 2025 at 11:13:43PM +0800, Hans Zhang wrote:
> Add the debugfs property to provide a view of the current link's LTSSM
> status from the root port device.
> 
>   /sys/kernel/debug/dwc_pcie_<dev>/ltssm_status
> 
> Signed-off-by: Hans Zhang <18255117159@163.com>
> ---
> Changes since v1:
> https://lore.kernel.org/linux-pci/20250123071326.1810751-1-18255117159@163.com/
> 
> - Do not place into sysfs node as recommended by maintainer. Shradha-based patch
>   is put into debugfs.
> - Submissions based on the following patches:
> https://patchwork.kernel.org/project/linux-pci/patch/20250121111421.35437-2-shradha.t@samsung.com/
> https://patchwork.kernel.org/project/linux-pci/patch/20250121111421.35437-3-shradha.t@samsung.com/
> https://patchwork.kernel.org/project/linux-pci/patch/20250121111421.35437-4-shradha.t@samsung.com/
> https://patchwork.kernel.org/project/linux-pci/patch/20250121111421.35437-5-shradha.t@samsung.com/
> ---
>  Documentation/ABI/testing/debugfs-dwc-pcie    |  6 ++
>  .../controller/dwc/pcie-designware-debugfs.c  | 70 ++++++++++++++++---
>  .../pci/controller/dwc/pcie-designware-ep.c   |  4 +-
>  .../pci/controller/dwc/pcie-designware-host.c | 54 +++++++++++++-
>  drivers/pci/controller/dwc/pcie-designware.h  | 43 ++++++++++--
>  5 files changed, 159 insertions(+), 18 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/debugfs-dwc-pcie b/Documentation/ABI/testing/debugfs-dwc-pcie
> index d3f84f46b400..bf0116012175 100644
> --- a/Documentation/ABI/testing/debugfs-dwc-pcie
> +++ b/Documentation/ABI/testing/debugfs-dwc-pcie
> @@ -142,3 +142,9 @@ Description:	(RW) Some lanes in the event list are lane specific events. These i
>  		events 1) - 11) and 34) - 35).
>  		Write lane number for which counter needs to be enabled/disabled/dumped.
>  		Read will return the current selected lane number. Lane0 is selected by default.
> +
> +What:		/sys/kernel/debug/dwc_pcie_<dev>/ltssm_status
> +Date:		February 2025
> +Contact:	Hans Zhang <18255117159@163.com>
> +Description:	(RO) Read will return the current value of the PCIe link status raw value and
> +		string status.
> diff --git a/drivers/pci/controller/dwc/pcie-designware-debugfs.c b/drivers/pci/controller/dwc/pcie-designware-debugfs.c
> index 5d883b13be84..ddfb854aa684 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-debugfs.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-debugfs.c
> @@ -465,7 +465,7 @@ static const struct file_operations dwc_pcie_counter_value_ops = {
>  	.read = counter_value_read,
>  };
>  
> -void dwc_pcie_rasdes_debugfs_deinit(struct dw_pcie *pci)
> +static void dwc_pcie_rasdes_debugfs_deinit(struct dw_pcie *pci)
>  {
>  	struct dwc_pcie_rasdes_info *rinfo = pci->rasdes_info;
>  
> @@ -473,13 +473,12 @@ void dwc_pcie_rasdes_debugfs_deinit(struct dw_pcie *pci)
>  	mutex_destroy(&rinfo->reg_lock);
>  }
>  
> -int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci)
> +static int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci, struct dentry *dir)
>  {
> -	struct dentry *dir, *rasdes_debug, *rasdes_err_inj, *rasdes_event_counter, *rasdes_events;
> +	struct dentry *rasdes_debug, *rasdes_err_inj, *rasdes_event_counter, *rasdes_events;
>  	struct dwc_pcie_rasdes_info *rasdes_info;
>  	struct dwc_pcie_rasdes_priv *priv_tmp;
>  	const struct dwc_pcie_vendor_id *vid;
> -	char dirname[DWC_DEBUGFS_BUF_MAX];
>  	struct device *dev = pci->dev;
>  	int ras_cap, i, ret;
>  
> @@ -498,12 +497,6 @@ int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci)
>  	if (!rasdes_info)
>  		return -ENOMEM;
>  
> -	/* Create main directory for each platform driver */
> -	snprintf(dirname, DWC_DEBUGFS_BUF_MAX, "dwc_pcie_%s", dev_name(dev));
> -	dir = debugfs_create_dir(dirname, NULL);
> -	if (IS_ERR(dir))
> -		return PTR_ERR(dir);
> -
>  	/* Create subdirectories for Debug, Error injection, Statistics */
>  	rasdes_debug = debugfs_create_dir("rasdes_debug", dir);
>  	rasdes_err_inj = debugfs_create_dir("rasdes_err_inj", dir);
> @@ -559,3 +552,60 @@ int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci)
>  	dwc_pcie_rasdes_debugfs_deinit(pci);
>  	return ret;
>  }
> +
> +static int dwc_pcie_ltssm_status_show(struct seq_file *s, void *v)
> +{
> +	struct dw_pcie *pci = s->private;
> +	enum dw_pcie_ltssm val;
> +
> +	val = dw_pcie_get_ltssm(pci);
> +	seq_printf(s, "%s (0x%02x)\n", dw_ltssm_sts_string(val), val);
> +
> +	return 0;
> +}
> +
> +static int dwc_pcie_ltssm_status_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, dwc_pcie_ltssm_status_show, inode->i_private);
> +}
> +
> +static const struct file_operations dwc_pcie_ltssm_status_ops = {
> +	.open = dwc_pcie_ltssm_status_open,
> +	.read = seq_read,
> +};
> +
> +static void dwc_pcie_ltssm_debugfs_init(struct dw_pcie *pci, struct dentry *dir)
> +{
> +	debugfs_create_file("ltssm_status", 0444, dir, pci,
> +			    &dwc_pcie_ltssm_status_ops);
> +}
> +
> +void dwc_pcie_debugfs_deinit(struct dw_pcie *pci)
> +{
> +	dwc_pcie_rasdes_debugfs_deinit(pci);
> +	debugfs_remove_recursive(pci->debugfs);
> +}
> +
> +int dwc_pcie_debugfs_init(struct dw_pcie *pci)
> +{
> +	char dirname[DWC_DEBUGFS_BUF_MAX];
> +	struct device *dev = pci->dev;
> +	struct dentry *dir;
> +	int ret;
> +
> +	/* Create main directory for each platform driver */
> +	snprintf(dirname, DWC_DEBUGFS_BUF_MAX, "dwc_pcie_%s", dev_name(dev));
> +	dir = debugfs_create_dir(dirname, NULL);
> +	if (IS_ERR(dir))
> +		return PTR_ERR(dir);
> +
> +	pci->debugfs = dir;
> +	ret = dwc_pcie_rasdes_debugfs_init(pci, dir);
> +	if (ret)
> +		dev_dbg(dev, "rasdes debugfs init failed\n");
> +
> +	dwc_pcie_ltssm_debugfs_init(pci, dir);
> +
> +	return 0;
> +}
> +

Stray newline here.
This causes:

/home/nks/src/linux/.git/worktrees/linux-scratch/rebase-apply/patch:136: new blank line at EOF.
+
warning: 1 line adds whitespace errors.

when doing git am.


Also, this patch does not apply anymore, because of a conflict introduce by:
112aba9a7934 ("PCI: dwc: Remove LTSSM state test in dw_pcie_suspend_noirq()")

Which added:
+       DW_PCIE_LTSSM_DETECT_WAIT = 0x6,
to drivers/pci/controller/dwc/pcie-designware.h


Kind regards,
Niklas