[Sound-open-firmware] Introduce a module parameter to configure SOF driver debug output?

[Pierre-Louis Bossart]

>>
>> echo PCM0C 0 > /sys/kernel/debug/sof/trace_level will disable the trace of
>> capture host component of fw pipeline.
>>
>> It includes trace level for common trace (irq, ipc, dma, ssp, wait, lock, mem,
>> value) and for component/widget based loaded topology.
>> Common trace level control could be used for both kernel driver and fw side
>> at the same time.
> 
> Hi Yan,
> 
> I feel it would be nice but not necessary to use same debug interface or kernel module parameter to control both kernel debug message and FW trace output.
> 
> It's because the firmware components can be different from those of kernel driver. So we'd better not bind them together, and so users have the freedom to enable/disable either of them.

+1

> 
> To control the kernel debug message, I hesitate to introduce multiple parameters if a single parameter "debug" can work.
> 
> Thanks
> Mengdong
> 
> 
>> And 0 is for no trace, 1 is for normal trace, 2 is for normal and verbose trace.
>> I am waiting Liam's comfirmation for my questions which have been sent
>> previously and finish the v2 patch set. I can also add this feature into it in
>> the v2 patch set.
>> Thanks.
>>
>> Yan Wang
>>
>>
>>>
>>> Thanks
>>> Mengdong
>>>
>>>>
>>>>
>>>> Warm Regards,
>>>> Abhijeet
>>>>
>>>> -----Original Message-----
>>>> From: sof-intel-request at eclists.intel.com [mailto:sof-intel-
>>>> request at eclists.intel.com] On Behalf Of Lin, Mengdong
>>>> Sent: Friday, April 27, 2018 3:22 PM
>>>> To: sof-intel at eclists.intel.com
>>>> Cc: Lu, Yang A <yang.a.lu at intel.com>
>>>> Subject: Introduce a module parameter to configure SOF driver debug
>>>> output?
>>>>
>>>> Hi,
>>>>
>>>> Sorry for the long mail.
>>>>
>>>> The kernel debug message from SOF driver can help us to debug issues
>>>> and CI to provide hints for failed test cases. But it will be too
>>>> much to output all of debug message by default.
>>>>
>>>> So maybe we can try to manage SOF debug messages as drm does?
>>>>
>>>> DRM is kernel gfx subsystem and Intel i915 driver is based on it.
>>>> drm defines
>>>> a module parameter 'debug' for user to specify the DRM debug mode
>>>> when booting the kernel. The debug mode is actually a bit mask of
>>>> different message categories. By setting a suitable debug mode, user
>>>> or CI can make DRM driver output message of specified categories.
>>>> Usually we use drm.debug=0x0e to get most important debug messages.
>>>>
>>>> Maybe SOF driver can also define its categories for debug messages?
>>>> If this is
>>>> doable, we can do some RFC patch.
>>>>
>>>> Here is how drm defines its debug mode in
>>>> drivers/gpu/drm/drm_drv.c:
>>>>
>>>> MODULE_PARM_DESC(debug, "Enable debug output, where each bit
>> enables
>>>> a debug category.\n"
>>>> "\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n"
>>>> "\t\tBit 1 (0x02) will enable DRIVER messages (drm controller
>>>> code)\n"
>>>> "\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n"
>>>> "\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n"
>>>> "\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n"
>>>> "\t\tBit 5 (0x20) will enable VBL messages (vblank code)\n"
>>>> "\t\tBit 7 (0x80) will enable LEASE messages (leasing code)");
>>>> module_param_named(debug, drm_debug, int, 0600);
>>>>
>>>>
>>>> void drm_dev_printk(const struct device *dev, const char *level,
>>>> 		    unsigned int category, const char *function_name,
>>>> 		    const char *prefix, const char *format, ...) {
>>>> 	struct va_format vaf;
>>>> 	va_list args;
>>>>
>>>> 	if (category != DRM_UT_NONE && !(drm_debug & category))
>>>> 		return;
>>>>
>>>> 	va_start(args, format);
>>>> 	vaf.fmt = format;
>>>> 	vaf.va = &args;
>>>>
>>>> 	if (dev)
>>>> 		dev_printk(level, dev, DRM_PRINTK_FMT, function_name,
>> prefix,
>>>> 			   &vaf);
>>>> 	...
>>>>
>>>> }
>>>>
>>>> Then base on this, it defines macros for outputting of different
>>>> categories:
>>>>
>>>> #define DRM_DEV_DEBUG(dev, fmt, args...)
>>>> \
>>>> 	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_CORE, __func__, "",
>>>> fmt,	\
>>>> 		       ##args)
>>>>
>>>> #define DRM_DEBUG(fmt, ...)
>>
>>>> \
>>>> 	drm_printk(KERN_DEBUG, DRM_UT_CORE, fmt, ##__VA_ARGS__)
>>>>
>>>>
>>>> #define DRM_DEV_DEBUG_DRIVER(dev, fmt, args...)
>>>> 	\
>>>> 	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_DRIVER, __func__, "",
>>>> 	\
>>>> 		       fmt, ##args)
>>>>
>>>> #define DRM_DEBUG_DRIVER(fmt, ...)
>>
>>>> \
>>>> 	drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
>>>>
>>>>
>>>> #define DRM_DEV_DEBUG_KMS(dev, fmt, args...)
>>>> 	\
>>>> 	drm_dev_printk(dev, KERN_DEBUG, DRM_UT_KMS, __func__, "", fmt,
>>>> 	\
>>>> 		       ##args)
>>>>
>>>>
>>>>
>>>> Thanks
>>>> Mengdong
>>>