Messages in this thread | | | From | Mike Frysinger <> | Date | Tue, 11 Jan 2011 00:31:57 -0500 | Subject | Re: [PATCH] drivers: char: hvc: add Blackfin JTAG console support |
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On Mon, Jan 10, 2011 at 22:41, Arnd Bergmann wrote: > On Tuesday 11 January 2011, Mike Frysinger wrote: >> throughput seems to be a bit lower. the Blackfin JTAG hardware has >> basically a 4 byte fifo that is filled/consumed in a single shot. and >> the Blackfin can produce much faster than the host can consume. so >> atm, i have it send out 4 bytes, and the hvc layers take care of >> calling back into me at some point. if i add a busy loop to run a few >> hundred milliseconds (like HZ/4), it runs much nicer. but obviously >> doesnt give anyone else time to run. i cant schedule or anything as >> the write layers are called with a spin_lock_irqsave. any tips for >> how to speed this up a bit ? or is it a wash with hvc ? > > You could try lowering the hvc MIN_TIMEOUT value. If you want to > change it for blackfin, you could probably make it a configuration > option. However, if it really takes a few milliseconds that you need > to wait between two accesses, MIN_TIMEOUT should already be small > enough. > > You should really not need to sleep in your output function, as > the khvcd() timeout logic tries handling this in the best way. > There may be a bug in that logic though (wouldn't be the first one > there), so try to see what the timeouts are when you get into > this problem.
np, i'll poke around a bit. i'm ok with merging this driver now since it seems to be functionality equivalent to the old code. -mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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