On Mon, Feb 02, 2009 at 09:42:04AM +0000, Andy Green wrote: > | It also appears than any sort of write to the SD-card (even just 4 kB) > | can interrupt audio. I don't know if it's down to the hardware or a kernel > | bug. Reading from the SD-card seems to work fine. > > We do have to sit there spamming the 4KB into the Glamo memory before > starting the transaction. But it's not much different from having to > spam out the 4KB from the Glamo memory on read inside interrupt context > when notified it completed.
The problem doesn't get worse with larger writes. For example, just now I had sound break up for about a second with 'vmstat 1' showing 36 blocks output. Then 8-10 seconds later, 3964 blocks were output with no sound problem (that I could hear). > Maybe the card blocks for a long time after the write, and the next > command we try doesn't return a status for a long time and we sit > spinning for it. It's a SanDisk card, so I guess that possibility can't be ruled out. I'm now running a 2.6.28 kernel I compiled from http://git.openmoko.org/?p=kernel.git;a=shortlog;h=andy-tracking (snapshot 9029dff1f370018665a6e2999632a34fd0518f4d 'fix-pcf50633-set-charging-limit-with-usb-limit.patch') and the problem is still there. Perhaps you could give me a pointer as to where in the driver I would try to make a modification (or at least insert some printk to narrow down the problem)? FWIW, to produce some sound I'm using mikmod to play {Sound,Noise,Pro,Fast,Scream}Tracker modules with the OSS driver (modprobe snd-pcm-oss). Mikmod has modest CPU requirements, most of the time using less than 1 % according to 'top', so plain lack of CPU time isn't likely causing audio dropouts. Out of 10-15 attempts, I've twice managed to break up the audio with 'dd if=/dev/zero of=/dev/mmcblk0p3 count=1 bs=4k'. -- Rask Ingemann Lambertsen Danish law requires addresses in e-mail to be logged and stored for a year _______________________________________________ hardware mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/hardware
