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

[Lin, Mengdong]

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> -----Original Message-----
> From: Kumar, Abhijeet
> Sent: Friday, April 27, 2018 6:46 PM
> To: Lin, Mengdong <mengdong.lin at intel.com>; sof-intel at eclists.intel.com
> Cc: Lu, Yang A <yang.a.lu at intel.com>
> Subject: RE: Introduce a module parameter to configure SOF driver debug
> output?
> 
> Sorry for the +1 noise. :)
> But I really think the idea of supporting different debug levels is nice. And if
> others think that it is doable, then maybe I would love to contribute RFC
> patches.

Hi Pierre/Liam,

Would you like to share some advice? 
And if this is doable, how can we define the categories: IPC, PCM, TOPOLOGY, VIRTIO, DEV, DRIVER?

Then we may define some macro like:
SND_SOF_DEBUG_IPC(dev, fmt, args...)
SND_SOF_DEBUG_PCM(dev, fmt, args...)
SND_SOF_DEBUG_TPLG(dev, fmt, args...) ... for topology
...

And we can also define category for different levels:
SND_SOF_INFO_IPC
SND_SOF_WARN_IPC
SND_SOF_ERR_IPC
...
> 
> >drm defines a module parameter 'debug' for user to specify the DRM
> >debug mode when booting the kernel
> And adding my two cents to it.
> DRM provides a sysfs as well to change the value of debug parameters at
> runtime. So it's not the always case of providing the debug level in kernel
> cmdline.
> 
> cat /sys/module/drm/parameters/debug

Yes. This is nice :-)

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