Re: [PATCH v4 06/11] ASoC: SOF: Intel: Account for compress streams when servicing IRQs

[Cezary Rojewski <cezary.rojewski@intel.com>]

On 2020-01-31 17:39, Pierre-Louis Bossart wrote:
> Maybe be a paranoid check but the types used in this patch seem to need 
> additional work:
> 
>> diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h
>> index 9a8bf1eb7d69..9a24d57f0cf2 100644
>> --- a/include/sound/hdaudio.h
>> +++ b/include/sound/hdaudio.h
>> @@ -496,6 +496,7 @@ struct hdac_stream {
>>       bool locked:1;
>>       bool stripe:1;            /* apply stripe control */
>> +    unsigned long curr_pos;
> 
> 'long' is an error-prone definition...
> 
>>       /* timestamp */
>>       unsigned long start_wallclk;    /* start + minimum wallclk */
>>       unsigned long period_wallclk;    /* wallclk for period */
>> diff --git a/sound/soc/sof/intel/hda-stream.c 
>> b/sound/soc/sof/intel/hda-stream.c
>> index c0ab9bb2a797..c8920a60e346 100644
>> --- a/sound/soc/sof/intel/hda-stream.c
>> +++ b/sound/soc/sof/intel/hda-stream.c
>> @@ -571,6 +571,23 @@ bool hda_dsp_check_stream_irq(struct snd_sof_dev 
>> *sdev)
>>       return ret;
>>   }
>> +static void hda_dsp_set_bytes_transferred(struct hdac_stream *hstream,
>> +                      u64 buffer_size)
>> +{
>> +    unsigned int prev_pos;
>> +    int pos, num_bytes;
>> +
>> +    div_u64_rem(hstream->curr_pos, buffer_size, &prev_pos);
> 
> ... here you use it as a u64 value so I guess the intent was to use more 
> than 32 bits?
> 
> But then the u64 for the 'buffer size' argument is also not consistent 
> with the definition of div_u64_rem, it's got to be u32, or you wanted to 
> use div64_64_rem?
> 
> static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
> 
> prev_pos should also be declared as u32 to avoid any ambiguity.
> 
>> +    pos = snd_hdac_stream_get_pos_posbuf(hstream);
>> +
>> +    if (pos < prev_pos)
>> +        num_bytes = (buffer_size - prev_pos) +  pos;
>> +    else
>> +        num_bytes = pos - prev_pos;
>> +
>> +    hstream->curr_pos += num_bytes;
> 
> ... and here it's a never ending-increment that is likely to hit a 
> 32-bit ceiling.
> 
> I remember we made a mistake some time back on compressed stuff and 
> updated the counters to rely on 64 bits. Unless this is a hardware 
> counter (and then we should use u32 and deal with overflow), we should 
> use u64, no?

All addressed in v5, thanks for review!