[alsa-devel] [PATCH v3 07/14] ASoC: SOF: Add DSP firmware logger support

[Pierre-Louis Bossart]

On 12/11/18 5:21 PM, Andy Shevchenko wrote:
> On Tue, Dec 11, 2018 at 03:23:11PM -0600, Pierre-Louis Bossart wrote:
>> From: Liam Girdwood <liam.r.girdwood at linux.intel.com>
>>
>> This patch adds support for real-time DSP logging (timestamped events
>> and bespoke binary data) for firmware debug. The current solution
>> relies on DMA transfers to system memory that is then accessed by
>> userspace tools such as sof-logger. For Intel platforms, two types of
>> DMAs are currently used (GP-DMA for Baytrail/CherryTrail and HDaudio
>> DMA for SKL+)
>>
>> Due to historical reasons, the driver code follows the DSP firmware
>> conventions and refers to 'traces', but it is currently unrelated to
>> the Linux trace subsystem. Future solutions will include support for
>> more advanced hardware (e.g. MIPI Sys-T), additional formats and the
>> ability to enable/disable specific traces dynamically.
>> +	if (count > buffer_size - lpos)
>> +		count = buffer_size - lpos;
> min() / max() ?
>
>> +	/* make sure count is <= avail */
>> +	count = avail > count ? count : avail;
> ditto.
> Check entire series for such.
yep.
>
>> +	dfse->dfsentry = debugfs_create_file("trace", 0444, sdev->debugfs_root,
>> +					     dfse, &sof_dfs_trace_fops);
>> +	if (!dfse->dfsentry) {
>> +		dev_err(sdev->dev,
>> +			"error: cannot create debugfs entry for trace\n");
>> +		kfree(dfse);
>> +		return -ENODEV;
> Should not return an error. We must be fine w/o debugfs files.

Not sure I fully agree with the 'must'.

yes execution should proceed, but without debugfs we cannot, well, 
debug, so this is a real show-stopper

>
>> +	}
>> +
>> +	return 0;
>> +}