ALSA: hda - Force polling mode on CFL for fixing codec communication

BugLink: https://bugs.launchpad.net/bugs/1758800
We've observed too long probe time with Coffee Lake (CFL) machines,
and the likely cause is some communication problem between the
HD-audio controller and the codec chips.  While the controller expects
an IRQ wakeup for each codec response, it seems sometimes missing, and
it takes one second for the controller driver to time out and read the
response in the polling mode.

Although we aren't sure about the real culprit yet, in this patch, we
put a workaround by forcing the polling mode as default for CFL
machines; the polling mode itself isn't too heavy, and much better
than other workarounds initially suggested (e.g. disabling
power-save), at least.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199007
Fixes: e79b0006c45c ("ALSA: hda - Add Coffelake PCI ID")
Reported-and-tested-by: Hui Wang <hui.wang@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit a8d7bde23e7130686b76624b099f3e22dd38aef7)
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Acked-by: Aaron Ma <aaron.ma@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 5ae8ddab641220f2ebb0a1e85438302e50d2b861..f23db5f11d36fd64aa31ee0103753afa39b70ba5 100644 (file)
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -371,6 +371,7 @@ enum {
                                        ((pci)->device == 0x160c))
 
 #define IS_BXT(pci) ((pci)->vendor == 0x8086 && (pci)->device == 0x5a98)
+#define IS_CFL(pci) ((pci)->vendor == 0x8086 && (pci)->device == 0xa348)
 
 static char *driver_short_names[] = {
        [AZX_DRIVER_ICH] = "HDA Intel",
@@ -1740,6 +1741,10 @@ static int azx_create(struct snd_card *card, struct pci_dev *pci,
        else
                chip->bdl_pos_adj = bdl_pos_adj[dev];
 
+       /* Workaround for a communication error on CFL (bko#199007) */
+       if (IS_CFL(pci))
+               chip->polling_mode = 1;
+
        err = azx_bus_init(chip, model[dev], &pci_hda_io_ops);
        if (err < 0) {
                kfree(hda);