On Sat, Jan 15, 2022 at 12:29:18PM +0530, Nandakumar Edamana wrote:

Could compile and reload the module successfully, but the stuttering is still there.

Hi Nandakumar,

OK, my mistake, scratch that patch.

The codepath that activates Implicit Feedback when implicit_fb=1 is passed to the module as an option is the same that should activate when the quirk is in place.

Like I said, it's very strange that your device skips implicit feedback when the quirk is in place, but can pick implicit feedback when implicit_fb=1 is passed to the module as an option.

I've prepared some printk's hooked up to every codepath I can think of that will skip implicit feedback. Please test and share your results, always with dyndbg on.

--- implicit.c 2022-01-14 16:41:53.946606013 -0300 +++ implicit.c 2022-01-15 21:45:15.108655890 -0300 @@ -90,8 +90,10 @@ static int add_implicit_fb_sync_ep(struc

if (!alts) { iface = usb_ifnum_to_if(chip->dev, ifnum); - if (!iface || iface->num_altsetting < 2) + if (!iface || iface->num_altsetting < 2) { + printk(KERN_WARNING "implicit: add_implicit_fb_sync_ep(): not a usb_host_interface or less than 2 altsettings"); return 0; + } alts = &iface->altsetting[1]; }

@@ -242,17 +244,23 @@ static int __add_generic_implicit_fb(str struct usb_endpoint_descriptor *epd;

alts = snd_usb_get_host_interface(chip, iface, altset); - if (!alts) + if (!alts) { + printk(KERN_WARNING "implicit: __add_generic_implicit_fb(): not a usb_host_interface"); return 0; + }

if ((alts->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC && alts->desc.bInterfaceClass != USB_CLASS_AUDIO) || - alts->desc.bNumEndpoints < 1) + alts->desc.bNumEndpoints < 1) { + printk(KERN_WARNING "implicit: __add_generic_implicit_fb(): no endpoints or wrong Interface Class"); return 0; + } epd = get_endpoint(alts, 0); if (!usb_endpoint_is_isoc_in(epd) || - (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC) + (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC) { + printk(KERN_WARNING "implicit: __add_generic_implicit_fb(): not Isochronous IN or not Asynchronous"); return 0; + } return add_implicit_fb_sync_ep(chip, fmt, epd->bEndpointAddress, 0, iface, alts); } @@ -262,8 +270,10 @@ static int add_generic_implicit_fb(struc struct audioformat *fmt, struct usb_host_interface *alts) { - if ((fmt->ep_attr & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC) + if ((fmt->ep_attr & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC) { + printk(KERN_WARNING "implicit: add_generic_implicit_fb(): not Asynchronous"); return 0; + }

if (__add_generic_implicit_fb(chip, fmt, alts->desc.bInterfaceNumber + 1, @@ -302,8 +312,10 @@ static int audioformat_implicit_fb_quirk if (p) { switch (p->type) { case IMPLICIT_FB_GENERIC: + printk(KERN_WARNING "implicit: audioformat_implicit_fb_quirk(): matched GENERIC inside playback_implicit_fb_quirks[]"); return add_generic_implicit_fb(chip, fmt, alts); case IMPLICIT_FB_NONE: + printk(KERN_WARNING "implicit: audioformat_implicit_fb_quirk(): matched SKIP_DEV inside playback_implicit_fb_quirks[]"); return 0; /* No quirk */ case IMPLICIT_FB_FIXED: return add_implicit_fb_sync_ep(chip, fmt, p->ep_num, 0, @@ -311,6 +323,10 @@ static int audioformat_implicit_fb_quirk } }

+ else { + printk(KERN_WARNING "implicit: audioformat_implicit_fb_quirk(): no matches found inside playback_implicit_fb_quirks[]"); + } + /* Special handling for devices with capture quirks */ p = find_implicit_fb_entry(chip, capture_implicit_fb_quirks, alts); if (p) { @@ -354,6 +370,7 @@ static int audioformat_implicit_fb_quirk return add_generic_implicit_fb(chip, fmt, alts);

/* No quirk */ + printk(KERN_WARNING "implicit: audioformat_implicit_fb_quirk(): returning 0 because no quirk was found"); return 0; }