From mboxrd@z Thu Jan 1 00:00:00 1970 From: neilb@suse.de (NeilBrown) Date: Sat, 4 Feb 2012 09:10:48 +1100 Subject: patch "tty: serial: OMAP: ensure FIFO levels are set correctly in non-DMA" added to tty tree In-Reply-To: References: <13274430881471@kroah.org> <20120126042155.GA3185@suse.de> <20120126191604.GA15516@suse.de> <20120203150708.386951d2@notabene.brown> <20120203205401.5ddf241d@notabene.brown> <20120203231113.25ae2d3a@notabene.brown> Message-ID: <20120204091048.00c7e027@notabene.brown> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 3 Feb 2012 14:42:09 -0700 (MST) Paul Walmsley wrote: > One correction on this part... > > On Fri, 3 Feb 2012, Paul Walmsley wrote: > > > On Fri, 3 Feb 2012, NeilBrown wrote: > > > > > My theory is that there is a delay between the falling RX line waking the > > > system up, and the CPU enabling the UART - whether enabling the clocks or > > > doing a full config, I am not sure - though I think the former. > > > > > > Maybe if we could enable the UART clocks immediately after returning from the > > > WFI instruction we could avoid the corruption.... > > > > The PRCM should be re-enabling the UART's functional clock itself, with no > > kernel involvement. The sequence should go something like this > > (simplified): > > > > 1. I/O wakeup occurs > > > > 2. CORE & PER powerdomains are awakened > > > > 3. The UART notices an event on its input lines and deasserts its idle-ack > > It just occurred to me that, supposedly, the only UART input line that is > attached to the SWAKEUP signal is CTS. So the UART may not in fact be > able to deassert its idle-ack autonomously at this point. How does that relate to the RX_CTS_WU_EN bit which enables an interrupt on "a falling edge of pins RX, nCTS, or nDSR" This seems to be a "wakeup interrupt", bit it isn't clear what it wakes us. > > So you might want to give your clock re-enable after WFI idea a shot! It > would be interesting if it helps. Might be a bit beyond me at the moment :-( Thanks, NeilBrown > > I regret the oversight, > > > - Paul -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 828 bytes Desc: not available URL: