On Sun, Oct 17, 2021 at 09:02:30AM +0200, Takashi Iwai wrote: > On Sun, 17 Oct 2021 03:22:31 +0200, > Takashi Sakamoto wrote: > > > > Hi, > > > > On Fri, Oct 15, 2021 at 05:54:13PM +0200, Takashi Iwai wrote: > > > On Fri, 15 Oct 2021 10:08:15 +0200, > > > Takashi Sakamoto wrote: > > > > > > > > Hi, > > > > > > > > The purpose of this patchset is to add message parser to ALSA > > > > firewire-motu driver so that userspace applications can read information > > > > in message delivered by isochronous packet as well as PCM frames. > > > > The message includes information about hardware meter and user action > > > > over hardware component such as knob, and MIDI message bytes. > > > > > > > > Models in MOTU FireWire series can be categorized to 4 groups in regard > > > > of message mechanism: > > > > > > > > Group 1. 828 and 896 > > > > * quadlet message to registered destination address > > > > Group 2. 828mk2, 896hd, Traveler, 8 pre, Ultralite, 4 pre, and Audio Express > > > > * quadlet message to registered destination address > > > > * message delivered by isochronous packet > > > > Group 3. 828mk3, 896mk3, Ultralite mk3, Traveler mk3, and Track 16 > > > > * quadlet message to registered destination address > > > > * message delivered by isochronous packet > > > > * block message to registered destination address, including command > > > > Group 4. V3HD/V4HD > > > > * quadlet message to registered destination address > > > > * block message to registered destination address > > > > > > > > The patchset is for message delivered by isochronous packet in group 2 > > > > and 3. In Group 2, the message includes information of hardware meter, > > > > information of user action over hardware component. The model in Group > > > > 2 is called as 'register DSP' in the patchset since parameters of DSP > > > > can be configured by asynchronous transaction for register access. In > > > > Group 3, the message includes information of hardware meter only. The > > > > model in Group 3 is called as 'command DSP' since software and device > > > > communicate with commands transferred by asynchronous transaction in > > > > regard of DSP parameters. Two types of message parser is going to be > > > > added so that the driver caches images for the information. The cache > > > > is available for userspace application by ioctl commands newly introduced. > > > > > > > > I note that no control element is added for the hardware meters and user > > > > actions. It's expected for userspace application to retrieve and parse the > > > > information of image then operate for user-defined control element set. > > > > > > > > Takashi Sakamoto (11): > > > > ALSA: firewire-motu: add message parser to gather meter information in > > > > register DSP model > > > > ALSA: firewire-motu: add message parser for meter information in > > > > command DSP model > > > > ALSA: firewire-motu: add ioctl command to read cached hardware meter > > > > ALSA: firewire-motu: parse messages for mixer source parameters in > > > > register-DSP model > > > > ALSA: firewire-motu: parse messages for mixer output parameters in > > > > register DSP model > > > > ALSA: firewire-motu: parse messages for output parameters in register > > > > DSP model > > > > ALSA: firewire-motu: parse messages for line input parameters in > > > > register DSP model > > > > ALSA: firewire-motu: parse messages for input parameters in register > > > > DSP model > > > > ALSA: firewire-motu: add ioctl command to read cached DSP parameters > > > > ALSA: firewire-motu: queue event for parameter change in register DSP > > > > model > > > > ALSA: firewire-motu: notify event for parameter change in register DSP > > > > model > > > > > > Applied all patches now. Thanks. > > > > Thanks for your applying the above patches into your tree. I have some > > slight concerns about them. I'd like to ask your opinion. > > > > The snd_firewire_motu_command_dsp_meter structure includes array of 32 bit > > storage elements. As I added its documentation, the storage includes > > IEEE 764 binary32 values between 0.0 and +1.0. In the patchset I use __u32 > > type since I can find just a few usage of float type in UAPI header. In > > driver side, no floating point arithmetic is used since the float value > > is just constructed by gathering messages from target device. In the case, > > is it adequate to expose the value as float type in UAPI? > > > > Additionally, current ALSA control interface have no support for control > > element with float value, like SNDRV_CTL_ELEM_TYPE_IEEE764_BINARY32. As > > long as I know, no discussion about it in the list for recent decades. > > Have you ever seen such discussion in the list? (Here I intensionally > > ignore that we have several binary expressions for floating point since > > I'm just interested in the existence of discussion.) > > It's not been proposed, AFAIK. > > The biggest concern is that, *if* any reference or calculation of the > float type is required, what to do. e.g. the kernel has a validation > code for each values (min/max check), and how could it be implemented > for the float type? Indeed. It's probably unavoidable to min/max check and it brings issue to ALSA control core. It's absolutely out of my scope and thanks for your indication. Would I ask you opinion about my concern about firewire UAPI header? Is it allowed to use float type instead of __u32 type? > thanks, > > Takashi Thanks Takashi Sakamoto
