From mboxrd@z Thu Jan 1 00:00:00 1970 From: balbi@ti.com (Felipe Balbi) Date: Wed, 16 Jul 2014 11:46:54 -0500 Subject: [PATCH 4/5] tty: serial: 8250 core: add runtime pm In-Reply-To: <53C6AAE1.7090802@linutronix.de> References: <1405521903-5877-1-git-send-email-bigeasy@linutronix.de> <1405521903-5877-5-git-send-email-bigeasy@linutronix.de> <20140716151604.GG1365@saruman.home> <53C6A050.2050409@linutronix.de> <20140716160614.GI1365@saruman.home> <53C6AAE1.7090802@linutronix.de> Message-ID: <20140716164654.GC3016@saruman.home> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 16, 2014 at 06:40:01PM +0200, Sebastian Andrzej Siewior wrote: > On 07/16/2014 06:06 PM, Felipe Balbi wrote: > > >>> well, other than in probe and other functions which need to > >>> make sure clocks are on, but it seems unnecessary to > >>> enable/disable in every function. > >> > >> What do you have in mind? Do you plan to let the uart on while > >> the minicom is attached but is doing nothing? In that case, > >> ->startup() and ->shutdown() should be enough. > > > > no the idea was to keep it on for as long as it's transferring > > characters and idle it otherwise, if that can't be done easily, > > then I guess your way is the only way. > > But maybe we have to add some additional logic here to keep it up for > the transfer. I've been just (maybe over)thinking: If you send 300 > bytes over DMA via 300 baud it should take 10 seconds. The PM-timeout > could hit before the transfer is complete. hmm, good point. So we _do_ need a way to get early and only put after we know transfer has completed and I was assuming stop_tx() to be that hint, but apparently it isn't. > Same thing with hw-flowcontrol where you could get stalled for a few > seconds. > However it doesn't seem to be a problem in current omap-serial driver. I don't think current omap-serial driver is a great example. -- balbi -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: