lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 25 Apr 2013 15:21:06 +0200 From: Linus Walleij <linus.walleij@...aro.org> To: Russell King - ARM Linux <linux@....linux.org.uk> Cc: Lee Jones <lee.jones@...aro.org>, Rabin Vincent <rabin@....in>, Linus WALLEIJ <linus.walleij@...ricsson.com>, Arnd Bergmann <arnd@...db.de>, Vinod Koul <vinod.koul@...el.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Per Forlin <per.forlin@...ricsson.com>, Dan Williams <djbw@...com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org> Subject: Re: [PATCH 04/32] dmaengine: ste_dma40: Amalgamate DMA source and destination channel numbers On Thu, Apr 25, 2013 at 3:09 PM, Russell King - ARM Linux <linux@....linux.org.uk> wrote: > There's a problem with device to device transfers though - you have to > consider the rate at which the devices produce and consume data, and > whether they both can cope with differing data rates. > > Take for instance your audio in to audio out idea - even if they are > both operating at the same bits per sample and sample rate, if they are > independently clocked, chances are that the clocks are not exactly the > same, which means you will either underrun or overrun one of the FIFOs > in the system. This magically works for us, but yes, I think they had to use the same clock (simplest solution, anyway). It is/was a very real usecase, IIRC coming from roundtrip constraints in the GSM 3GPP spec, wanting to keep the latency as low as possible. With this scheme there is no more than a FIFO on each end of delay, which is nice. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists