This is a note to let you know that I've just added the patch titled
ALSA: hda - Force polling mode on CFL for fixing codec communication
to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: alsa-hda-force-polling-mode-on-cfl-for-fixing-codec-communication.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From a8d7bde23e7130686b76624b099f3e22dd38aef7 Mon Sep 17 00:00:00 2001
From: Takashi Iwai tiwai@suse.de Date: Wed, 21 Mar 2018 10:06:13 +0100 Subject: ALSA: hda - Force polling mode on CFL for fixing codec communication
From: Takashi Iwai tiwai@suse.de
commit a8d7bde23e7130686b76624b099f3e22dd38aef7 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/pci/hda/hda_intel.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -375,6 +375,7 @@ 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", @@ -1744,6 +1745,10 @@ static int azx_create(struct snd_card *c 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);
Patches currently in stable-queue which might be from tiwai@suse.de are
queue-4.15/alsa-aloop-fix-access-to-not-yet-ready-substream-via-cable.patch queue-4.15/alsa-hda-realtek-fix-speaker-no-sound-after-system-resume.patch queue-4.15/alsa-hda-realtek-fix-dell-headset-mic-can-t-record.patch queue-4.15/alsa-hda-realtek-always-immediately-update-mute-led-with-pin-vref.patch queue-4.15/alsa-usb-audio-fix-parsing-descriptor-of-uac2-processing-unit.patch queue-4.15/alsa-aloop-sync-stale-timer-before-release.patch queue-4.15/alsa-hda-force-polling-mode-on-cfl-for-fixing-codec-communication.patch