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

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Message-ID: <2c960f0c-5cbb-4c2d-07cb-dafd94d22414@linux.intel.com>
Date:   Mon, 17 Apr 2023 11:28:18 +0530
From:   Rajat Khandelwal <rajat.khandelwal@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
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

Hi,

On 4/15/2023 11:01 AM, Greg KH wrote:
> 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?

I'm sorry I didn't understand the question. We would have separate directories
for all the ports which would contain the 'iom_status' file, thus representing
status for all the ports individually.
Can you rephrase the question since I guess you had something else in mind?

Thanks
Rajat

>
> thanks,
>
> greg k-h