On Thu, 16 Jan 2020 05:53:18 +0100, Keyon Jie wrote: > > With today's code, we preallocate DMA buffer for substreams at pcm_new() > stage, and the substream->buffer_bytes_max and substream->dma_max will > save as the actually preallocated buffer size and maximum size that the > dma buffer can be expanded by at hw_params() state, correspondingly. No, it's other way round: the former, buffer_bytes_max, is the max size defined by the driver (i.e. passed in snd_pcm_hardware) and the latter, dma_max, is the max preallocation size (passed to preallocation helper). > At pcm_open() stage, the maximum constraint of HW_PARAM_BUFFER_BYTES is > set to substream->buffer_bytes_max and returned to user space as the max > interval of the HW_PARAM_BUFFER_BYTES, this will lead to issue that user > can't choose any buffer-bytes larger than the preallocated buffer size, > and the buffer reallocation will never happen actually. > > Here change to use substream->dma_max as the maximum constraint of the > HW_PARAM_BUFFER_BYTES and fix the issue mentioned above. I don't think the logic in the current code you're changing is wrong. If there is any, it must be something else. This might be rather the FIXME code found in snd_pcm_hw_constraints_complete()? thanks, Takashi > Signed-off-by: Keyon Jie <yang.jie@xxxxxxxxxxxxxxx> > --- > sound/core/pcm_native.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c > index c375c41496f8..326e921006e7 100644 > --- a/sound/core/pcm_native.c > +++ b/sound/core/pcm_native.c > @@ -2301,7 +2301,7 @@ static int snd_pcm_hw_rule_buffer_bytes_max(struct snd_pcm_hw_params *params, > struct snd_interval t; > struct snd_pcm_substream *substream = rule->private; > t.min = 0; > - t.max = substream->buffer_bytes_max; > + t.max = substream->dma_max; > t.openmin = 0; > t.openmax = 0; > t.integer = 1; > -- > 2.20.1 > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
