ASoC: SOF: SND_INTEL_DSP_CONFIG dependency

The sof-pci-dev driver fails to link when built into the kernel
and CONFIG_SND_INTEL_DSP_CONFIG is set to =m:

arm-linux-gnueabi-ld: sound/soc/sof/sof-pci-dev.o: in function `sof_pci_probe':
sof-pci-dev.c:(.text+0x1c): undefined reference to `snd_intel_dsp_driver_probe'

As a temporary fix, use IS_REACHABLE to prevent the problem from
happening. A more complete solution is to move this code to
Intel-specific parts, restructure the drivers and Kconfig as discussed
with Arnd Bergmann and Takashi Iwai.

Fixes: 82d9d54a ("ALSA: hda: add Intel DSP configuration / probe code")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210122005725.94163-3-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/sof-acpi-dev.c

@@ -131,12 +131,13 @@ static int sof_acpi_probe(struct platform_device *pdev)
 	if (!id)
 		return -ENODEV;
 
-	ret = snd_intel_acpi_dsp_driver_probe(dev, id->id);
-	if (ret != SND_INTEL_DSP_DRIVER_ANY && ret != SND_INTEL_DSP_DRIVER_SOF) {
-		dev_dbg(dev, "SOF ACPI driver not selected, aborting probe\n");
-		return -ENODEV;
+	if (IS_REACHABLE(CONFIG_SND_INTEL_DSP_CONFIG)) {
+		ret = snd_intel_acpi_dsp_driver_probe(dev, id->id);
+		if (ret != SND_INTEL_DSP_DRIVER_ANY && ret != SND_INTEL_DSP_DRIVER_SOF) {
+			dev_dbg(dev, "SOF ACPI driver not selected, aborting probe\n");
+			return -ENODEV;
+		}
 	}
-
 	dev_dbg(dev, "ACPI DSP detected");
 
 	sof_pdata = devm_kzalloc(dev, sizeof(*sof_pdata), GFP_KERNEL);

sound/soc/sof/sof-pci-dev.c

@@ -344,10 +344,12 @@ static int sof_pci_probe(struct pci_dev *pci,
 	const struct snd_sof_dsp_ops *ops;
 	int ret;
 
-	ret = snd_intel_dsp_driver_probe(pci);
-	if (ret != SND_INTEL_DSP_DRIVER_ANY && ret != SND_INTEL_DSP_DRIVER_SOF) {
-		dev_dbg(&pci->dev, "SOF PCI driver not selected, aborting probe\n");
-		return -ENODEV;
+	if (IS_REACHABLE(CONFIG_SND_INTEL_DSP_CONFIG)) {
+		ret = snd_intel_dsp_driver_probe(pci);
+		if (ret != SND_INTEL_DSP_DRIVER_ANY && ret != SND_INTEL_DSP_DRIVER_SOF) {
+			dev_dbg(&pci->dev, "SOF PCI driver not selected, aborting probe\n");
+			return -ENODEV;
+		}
 	}
 	dev_dbg(&pci->dev, "PCI DSP detected");