linux-kernel - Re: [PATCH v2] usb: typec: intel_pmc_mux: Expose IOM port status to debugfs

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Date:   Sat, 15 Apr 2023 07:31:07 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
Cc:     heikki.krogerus@...ux.intel.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] usb: typec: intel_pmc_mux: Expose IOM port status to
 debugfs

On Fri, Apr 14, 2023 at 01:49:10PM +0530, Rajat Khandelwal wrote:
> IOM status has a crucial role during debugging to check the
> current state of the type-C port.
> There are ways to fetch the status, but all those require the
> IOM port status offset, which could change with platform.
> 
> Make a debugfs directory for intel_pmc_mux and expose the status
> under it per port basis.
> 
> Signed-off-by: Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
> ---
> 
> v2:
> 1. Remove static declaration of the debugfs root for 'intel_pmc_mux'
> 2. Remove explicitly defined one-liner functions
> 
>  drivers/usb/typec/mux/intel_pmc_mux.c | 34 +++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
> index 34e4188a40ff..1d43b111781e 100644
> --- a/drivers/usb/typec/mux/intel_pmc_mux.c
> +++ b/drivers/usb/typec/mux/intel_pmc_mux.c
> @@ -15,6 +15,7 @@
>  #include <linux/usb/typec_mux.h>
>  #include <linux/usb/typec_dp.h>
>  #include <linux/usb/typec_tbt.h>
> +#include <linux/debugfs.h>
>  
>  #include <asm/intel_scu_ipc.h>
>  
> @@ -639,9 +640,34 @@ static int pmc_usb_probe_iom(struct pmc_usb *pmc)
>  	return 0;
>  }
>  
> +static int port_iom_status_show(struct seq_file *s, void *unused)
> +{
> +	struct pmc_usb_port *port = s->private;
> +
> +	update_port_status(port);
> +	seq_printf(s, "0x%08x\n", port->iom_status);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(port_iom_status);
> +
> +static void pmc_mux_port_debugfs_init(struct pmc_usb_port *port,
> +				      struct dentry *pmc_mux_debugfs_root)
> +{
> +	struct dentry *debugfs_dir;
> +	char name[6];
> +
> +	snprintf(name, sizeof(name), "port%d", port->usb3_port - 1);
> +
> +	debugfs_dir = debugfs_create_dir(name, pmc_mux_debugfs_root);
> +	debugfs_create_file("iom_status", 0400, debugfs_dir, port,
> +			    &port_iom_status_fops);
> +}
> +
>  static int pmc_usb_probe(struct platform_device *pdev)
>  {
>  	struct fwnode_handle *fwnode = NULL;
> +	struct dentry *pmc_mux_debugfs_root;
>  	struct pmc_usb *pmc;
>  	int i = 0;
>  	int ret;
> @@ -674,6 +700,8 @@ static int pmc_usb_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	pmc_mux_debugfs_root = debugfs_create_dir("intel_pmc_mux", NULL);

What happens when you have more than one device in the system at the
same time?

thanks,

greg k-h