On 9/12/2023 6:32 PM, Richard Fitzgerald wrote:
Add members to struct snd_soc_card to store the PCI subsystem ID (SSID) of the soundcard.
The PCI specification provides two registers to store a vendor-specific SSID that can be read by drivers to uniquely identify a particular "soundcard". This is defined in the PCI specification to distinguish products that use the same silicon (and therefore have the same silicon ID) so that product-specific differences can be applied.
PCI only defines 0xFFFF as an invalid value. 0x0000 is not defined as invalid. So the usual pattern of zero-filling the struct and then assuming a zero value unset will not work. A flag is included to indicate when the SSID information has been filled in.
Unlike DMI information, which has a free-format entirely up to the vendor, the PCI SSID has a strictly defined format and a registry of vendor IDs.
It is usual in Windows drivers that the SSID is used as the sole identifier of the specific end-product and the Windows driver contains tables mapping that to information about the hardware setup, rather than using ACPI properties.
This SSID is important information for ASoC components that need to apply hardware-specific configuration on PCI-based systems.
As the SSID is a generic part of the PCI specification and is treated as identifying the "soundcard", it is reasonable to include this information in struct snd_soc_card, instead of components inventing their own custom ways to pass this information around.
Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com
include/sound/soc-card.h | 37 +++++++++++++++++++++++++++++++++++++ include/sound/soc.h | 11 +++++++++++ 2 files changed, 48 insertions(+)
diff --git a/include/sound/soc-card.h b/include/sound/soc-card.h index fc94dfb0021f..e8ff2e089cd0 100644 --- a/include/sound/soc-card.h +++ b/include/sound/soc-card.h
...
diff --git a/include/sound/soc.h b/include/sound/soc.h index 509386ff5212..81ed08c5c67d 100644 --- a/include/sound/soc.h +++ b/include/sound/soc.h @@ -929,6 +929,17 @@ struct snd_soc_card { #ifdef CONFIG_DMI char dmi_longname[80]; #endif /* CONFIG_DMI */
+#ifdef CONFIG_PCI
- /*
* PCI does not define 0 as invalid, so pci_subsystem_set indicates* whether a value has been written to these fields.*/- unsigned short pci_subsystem_vendor;
- unsigned short pci_subsystem_device;
- bool pci_subsystem_set;
+#endif /* CONFIG_PCI */
char topology_shortname[32];
struct device *dev;
This looks bit weird to me, snd_soc_card is _generic_ struct which is not device specific in any way, and now you add fields for PCI, can't this somehow be done using drvdata or something?