Messages in this thread | | | Subject | Re: [PATCH 1/2] ALSA: firewire-tascam: Fix infinite loop in snd_tscm_stream_get_rate() | From | Takashi Sakamoto <> | Date | Mon, 15 May 2017 23:40:12 +0900 |
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On May 15 2017 23:22, Geert Uytterhoeven wrote: >>> diff --git a/sound/firewire/tascam/tascam-stream.c >>> b/sound/firewire/tascam/tascam-stream.c >>> index f1657a4e0621ef49..e433b92ac6904db5 100644 >>> --- a/sound/firewire/tascam/tascam-stream.c >>> +++ b/sound/firewire/tascam/tascam-stream.c >>> @@ -84,7 +84,7 @@ int snd_tscm_stream_get_rate(struct snd_tscm *tscm, >>> unsigned int *rate) >>> unsigned int trials = 0; >>> int err; >>> >>> - while (data == 0x0 || trials++ < 5) { >>> + while (data == 0x0 && trials++ < 5) { >>> err = get_clock(tscm, &data); >>> if (err < 0) >>> return err; >> >> Yep. It looks a bug. >> >> ...However, removal of the bug causes issue that the driver fails to start a >> pair of capture/playback PCM substream when application requests them mostly >> the same time, like jackd process. >> >> I think I did apply the bug as a makeshift workaround, then forgot itself >> when developing the driver... I'd like to have a bit time for further >> investigation, then post my fix in this development period. > > Probably you need a small delay in the loop? > Why else do you #include <linux/delay.h>? ;-)
I know PDI1394L40 (link layer) has quirks inconvenient to us. Furthermore, the behaviour of on-board FPGAs with unique firmwares are in black boxes to me.
I prefer deliberate approach for this kind of work, reverse engineering.
Regards
Takashi Sakamoto
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