Hi Takashi,
Dne 07. 07. 20 v 11:40 Takashi Iwai napsal(a):
On Fri, 03 Jul 2020 12:17:14 +0200,
Pavel Hofman wrote:
Dne 02. 07. 20 v 13:28 Pavel Hofman napsal(a):
Please is the requirement that EP OUT + EP IN implicit feedback data
must be in the same interface really necessary? If such a requirement
was dropped, IMO many devices could be removed from the existing
set_sync_ep_implicit_fb_quirk and many devices would work out of the
box,
I am still thinking about the single-interface requirement. If both
endpoints were to be part of a single interface, could they use
different altsettings for different sample lengths for capture and
playback? E.g. to save USB bandwidth when the capture is used only for
implicit feedback - capturing at 16bits, playback at 32bits.
In the quirked XMOS devices the common clock for both directions is
defined by the clock feature, the altsettings for each direction (in
separate interfaces) are used for setting sample length.
Could you check for-linus branch of my sound git tree?
Just to be sure whether you're hitting the issue that has been already
addressed.
I developed the RTX6001 patch on 5.8-rc3 kernel, and commits since that
tag in
https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/log/?h=for-linus
do not seem to address the issue.
I think the generic code searching for the implicit-feedback endpoint
works only on the current interface (alts)
https://github.com/tiwai/sound/blob/master/sound/usb/pcm.c#L491
I do not know if searching for IN endpoints with the same number and
USB_ENDPOINT_USAGE_IMPLICIT_FB mask in other interfaces is correct. But
it seems to me it would yield correct results for a number of existing
quirks in set_sync_ep_implicit_fb_quirk (typically those setting ep=0x81).
Thanks a lot,
Pavel.
