>>>>>> + .name_prefix = "cs35l56-8" >>>>> >>>>> Can these prefixes be "AMPn" to match the CS35L41, CS35L51 and >>>>> CS35L56-hda driver? This prefix is used to find the matching firmware >>>>> files and our naming convention for these has been cs35lxx-xxxx-ampn >>>>> >>>>> Is there anything that depends on the prefixes being "cs35l56-n" ? >>>> >>>> IIRC this name_prefix is just used for the codec_conf and hence for >>>> control names/UCM. At some point userspace/driver need to know if amp5 >>>> is left or right. >>>> >>>> We can certainly align on conventions but the values set in this ACPI >>>> match table will not be used for firmware download - different scope. >>>> >>> >>> They are used for our firmware download. Each amp can have its own >>> unique firmware file. The ALSA prefix is used to identify which firmware >>> file to load to which amp. >> >> The prefix will only be used when the card is created, specifically for >> control names. >> The firmware should be selected and downloaded when the device shows up >> on the bus. >> Card creation and device enumeration/initialization happen on different >> timelines, if the machine driver is "blacklisted" or unbound I am not >> sure what happens. >> >> There is a dependency between machine driver probe and codec firmware >> download that I am not able to follow, can you please elaborate? >> > > The codec driver has to choose which firmware to load from under > /lib/firmware. It does this using a combination of SSID (to identify the > target product), the ALSA prefix string (to identify which amp) and > in some systems a GPIO on the motherboard to select between different > models of speaker when they have multiple suppliers. This results in a > firmware name like: > > cs35l56-<silicon rev>-dsp1-misc-<SSID>[-<SPEAKER MODEL>]-<ALSA PREFIX> > > You can see this if you look in the linux-firmware repo under cirrus/ > for cs35l41 firmware files (though the ALSA PREFIX section in those > cases is not "AMPn" because they are not SDCA parts with rotation, > they have a fixed left/right assignment.) > > We have to be careful of the length of the prefix. The 44 characters of > an ALSA control name get eaten up very quickly when we start creating > fully-qualified names for controls published by the firmware. So "AMPn" > was nice because it was descriptive enough but only uses 5 characters > of the 44. > > Having said that, I've calculated that we have enough characters (just) > to use a prefix of "cs35l56-n". If there's a reason why that is > necessary/desirable for SOF or SoundWire then we could do that. But we'd > intended to use "AMPn" prefixes. > > We just need to decide whether to go with "AMPn". Or switch to using > "cs35l56-n" for the ALSA prefix (the therefore the qualifier at the end > of the firmware filename). Yes we have similar issues with control names in topology, the limit is hit very quickly. I think you missed my point though that the ALSA prefix is only set when the card is created, which can be sometime after the firmware needs to be downloaded. I guess you could pick the firmware in the component probe, which happens during the card creation, but that could be sub-optimal. Given the download times you want the download to proceed as early as possible.
