Re: [PATCH V1 2/3] ALSA: hda: add bus callback for address translation

[Takashi Iwai <tiwai@suse.de>]

On Thu, 27 Nov 2025 10:44:26 +0100,
Joakim  Zhang wrote:
> 
> [...]
> > >  include/sound/hdaudio.h     |  3 +++
> > >  sound/hda/core/controller.c | 25 +++++++++++++++++++------
> > >  sound/hda/core/stream.c     | 17 ++++++++++++++---
> > >  3 files changed, 36 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h index
> > > 4e0c1d8af09f..61b41a014f4a 100644
> > > --- a/include/sound/hdaudio.h
> > > +++ b/include/sound/hdaudio.h
> > > @@ -293,6 +293,9 @@ struct hdac_bus {
> > >       const struct hdac_bus_ops *ops;
> > >       const struct hdac_ext_bus_ops *ext_ops;
> > >
> > > +     /* address translation from host to hdac */
> > > +     dma_addr_t (*addr_host_to_hdac)(struct hdac_bus *bus, dma_addr_t
> > > + addr);
> >
> > This should be rather added to hdac_bus_ops instead.
> >
> > Or, we can just add addr_offset field in hdac_bus instead of yet another
> > callback.  Then the change would be simpler.
> >
> 
> Hello Takashi,
> 
> Sorry for late updating since I am involving in other tasks recently.
> 
> I tried to add addr_offset field in hdac_bus for the address translation, but met the issue,
> e.g.
> On our platform, if HOST address is 0xd0c09000, HDAC address is 0xd0c09000 - 0x90000000 = 0x40c09000.
> 
> If we use the pattern, HOST_addr + addr_offset = HDAC_addr
> For 64bit host,
> then addr_offset shound be 0x70000000, 0xd0c09000+0x70000000=0x1_40c09000, it will update both lower 32bit and
> upper 32bit into hda registers. However, hda controller in our audio subsystem can only support 32bit address, if hda
>  sending address more than 32bit, it would not work.

Hm, I don't understand.  It we define something like

	dma_addr_t addr_offset;

in hdac_bus, and the driver setting

	bus->addr_offset = -0x90000000;

then a calculation

	dma_addr_t addr;

	addr = bus->rb.addr + bus->addr_offset;
	
will lead to the very same result as your callback, no?
Or am I missing something?


thanks,

Takashi