[alsa-devel] [PATCH 1/4] ALSA: memalloc: Allow NULL device for SNDRV_DMA_TYPE_CONTINOUS type

[Takashi Iwai]

On Tue, 05 Nov 2019 19:28:44 +0100,
Amadeusz Sławiński wrote:
> 
> On Tue,  5 Nov 2019 09:01:35 +0100
> Takashi Iwai <tiwai at suse.de> wrote:
> 
> > Currently we pass the artificial device pointer to the allocation
> > helper in the case of SNDRV_DMA_TYPE_CONTINUOUS for passing the GFP
> > flags.  But all common cases are the allocations with GFP_KERNEL, and
> > it's messy to put this in each place.
> > 
> > In this patch, the memalloc core helper is changed to accept the NULL
> > device pointer and it treats as the default mode, GFP_KERNEL, so that
> > all callers can omit the complex argument but just leave NULL.
> > 
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > ---
> >  Documentation/sound/kernel-api/writing-an-alsa-driver.rst | 14 ++++++++------
> >  sound/core/memalloc.c                                     |  9 ++++++++-
> >  2 files changed, 16 insertions(+), 7 deletions(-)
> > 
> > diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> > index 132f5eb9b530..5385618fd881 100644
> > --- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> > +++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
> > @@ -3523,12 +3523,14 @@ The second argument (type) and the third argument (device pointer) are
> >  dependent on the bus. For normal devices, pass the device pointer
> >  (typically identical as ``card->dev``) to the third argument with
> >  ``SNDRV_DMA_TYPE_DEV`` type. For the continuous buffer unrelated to the
> > -bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type and the
> > -``snd_dma_continuous_data(GFP_KERNEL)`` device pointer, where
> > -``GFP_KERNEL`` is the kernel allocation flag to use. For the
> > -scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the device
> > -pointer (see the `Non-Contiguous Buffers`_
> > -section).
> > +bus can be pre-allocated with ``SNDRV_DMA_TYPE_CONTINUOUS`` type.
> > +You can pass NULL to the device pointer in that case, which is the
> > +default mode implying to allocate with ``GFP_KRENEL`` flag.
> > +If you need a different GFP flag, you can pass it by encoding the flag
> > +into the device pointer via a special macro
> > +:c:func:`snd_dma_continuous_data()`.
> > +For the scatter-gather buffers, use ``SNDRV_DMA_TYPE_DEV_SG`` with the
> > +device pointer (see the `Non-Contiguous Buffers`_ section).
> >  
> >  Once the buffer is pre-allocated, you can use the allocator in the
> >  ``hw_params`` callback:
> > diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
> > index 6850d13aa98c..e56f84fbd659 100644
> > --- a/sound/core/memalloc.c
> > +++ b/sound/core/memalloc.c
> > @@ -99,6 +99,13 @@ static void snd_free_dev_iram(struct snd_dma_buffer *dmab)
> >   *
> >   */
> >  
> > +static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev)
> > +{
> > +	if (!dev)
> > +		return GFP_KRENEL;
> 
> There is a typo, you remove it in next patch, but it may cause problem
> with bisects.

Indeed, will fix up.


thanks,

Takashi