From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> To: Peter Hurley <peter@hurleysoftware.com> Cc: Frans Klaver <frans.klaver@xsens.com>, Heikki Krogerus <heikki.krogerus@linux.intel.com>, tony@atomide.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, balbi@ti.com, linux-serial@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Alan Cox <alan@linux.intel.com> Subject: Re: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Date: Wed, 24 Sep 2014 09:53:46 +0200 [thread overview] Message-ID: <20140924075346.GB19565@linutronix.de> (raw) In-Reply-To: <5421A7F7.3070109@hurleysoftware.com> * Peter Hurley | 2014-09-23 13:03:51 [-0400]: >readline() does this; it 'saves' the caller's termios, sets termios >for non-canonical reads, reads one char, and 'restores' the caller's >termios. interresting, thanks. I guess I would need to opimize this a little so the baudrate isn't going to 0 and back to the requested baudrate. >The tty core calls the driver's wait_until_sent() method before changing >the termios (if TCSADRAIN is used for tcsetattr(), which I think for readline() >it does). The interresting difference is that when I take the yocto RFS and chroot into from Debian then I don't this problem. Not sure if this is really readline or something else… >But DMA is cheating if the UART driver's tx_empty() method is saying the >transmitter is empty while TX DMA is still running. This shouldn't be the case. But I will check this once I able to. After TX-DMA is done, "xmit->tail" is updated and port.icount.tx is incremented. At this time the TX FIFO is still full (up to 64 bytes) and I set UART_IER_THRI to wait until TX FIFO is empty so I can disable runtime-pm. Therefore I would assume LSR does not say BOTH_EMPTY until the FIFO is empty. >Regards, >Peter Hurley Sebastian
WARNING: multiple messages have this Message-ID (diff)
From: bigeasy@linutronix.de (Sebastian Andrzej Siewior) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Date: Wed, 24 Sep 2014 09:53:46 +0200 [thread overview] Message-ID: <20140924075346.GB19565@linutronix.de> (raw) In-Reply-To: <5421A7F7.3070109@hurleysoftware.com> * Peter Hurley | 2014-09-23 13:03:51 [-0400]: >readline() does this; it 'saves' the caller's termios, sets termios >for non-canonical reads, reads one char, and 'restores' the caller's >termios. interresting, thanks. I guess I would need to opimize this a little so the baudrate isn't going to 0 and back to the requested baudrate. >The tty core calls the driver's wait_until_sent() method before changing >the termios (if TCSADRAIN is used for tcsetattr(), which I think for readline() >it does). The interresting difference is that when I take the yocto RFS and chroot into from Debian then I don't this problem. Not sure if this is really readline or something else? >But DMA is cheating if the UART driver's tx_empty() method is saying the >transmitter is empty while TX DMA is still running. This shouldn't be the case. But I will check this once I able to. After TX-DMA is done, "xmit->tail" is updated and port.icount.tx is incremented. At this time the TX FIFO is still full (up to 64 bytes) and I set UART_IER_THRI to wait until TX FIFO is empty so I can disable runtime-pm. Therefore I would assume LSR does not say BOTH_EMPTY until the FIFO is empty. >Regards, >Peter Hurley Sebastian
next prev parent reply other threads:[~2014-09-24 7:54 UTC|newest] Thread overview: 236+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-09-10 19:29 [PATCH 00/16 v9] omap 8250 based uart + DMA Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-10 19:29 ` [PATCH 01/16] tty: serial: 8250_core: allow to set ->throttle / ->unthrottle callbacks Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-10 19:29 ` [PATCH 02/16] tty: serial: 8250_core: add run time pm Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-29 9:46 ` Frans Klaver 2014-09-29 9:46 ` Frans Klaver 2014-09-29 9:46 ` Frans Klaver 2014-09-29 13:39 ` Sebastian Andrzej Siewior 2014-09-29 13:39 ` Sebastian Andrzej Siewior 2014-09-10 19:29 ` [PATCH 03/16] tty: serial: 8250_core: read only RX if there is something in the FIFO Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2015-02-09 13:34 ` Nicolas Schichan 2015-02-09 13:34 ` Nicolas Schichan 2015-02-09 23:34 ` Peter Hurley 2015-02-09 23:34 ` Peter Hurley 2015-02-10 9:32 ` Sebastian Andrzej Siewior 2015-02-10 9:32 ` Sebastian Andrzej Siewior 2015-02-10 12:04 ` Nicolas Schichan 2015-02-10 12:04 ` Nicolas Schichan 2015-02-10 17:46 ` Peter Hurley 2015-02-10 17:46 ` Peter Hurley 2015-02-11 20:01 ` Peter Hurley 2015-02-11 20:01 ` Peter Hurley 2015-02-11 20:03 ` Tony Lindgren 2015-02-11 20:03 ` Tony Lindgren 2015-02-11 20:03 ` Tony Lindgren 2015-02-11 20:42 ` Peter Hurley 2015-02-11 20:42 ` Peter Hurley 2015-02-12 8:45 ` Sebastian Andrzej Siewior 2015-02-12 8:45 ` Sebastian Andrzej Siewior 2015-02-12 9:40 ` Russell King - ARM Linux 2015-02-12 9:40 ` Russell King - ARM Linux 2015-02-12 16:32 ` Peter Hurley 2015-02-12 16:32 ` Peter Hurley 2015-02-12 19:23 ` Sebastian Andrzej Siewior 2015-02-12 19:23 ` Sebastian Andrzej Siewior 2015-02-12 19:55 ` Peter Hurley 2015-02-12 19:55 ` Peter Hurley 2015-02-12 20:34 ` Sebastian Andrzej Siewior 2015-02-12 20:34 ` Sebastian Andrzej Siewior 2015-02-13 18:51 ` Sebastian Andrzej Siewior 2015-02-13 18:51 ` Sebastian Andrzej Siewior 2015-02-13 23:15 ` Russell King - ARM Linux 2015-02-13 23:15 ` Russell King - ARM Linux 2015-02-15 17:32 ` [PATCH] serial: 8250: Revert "tty: serial: 8250_core: read only RX if there is something in the FIFO" Sebastian Andrzej Siewior 2015-02-15 17:32 ` Sebastian Andrzej Siewior 2015-05-12 20:25 ` Tony Lindgren 2015-05-12 20:25 ` Tony Lindgren 2014-09-10 19:29 ` [PATCH 04/16] tty: serial: 8250_core: use the ->line argument as a hint in serial8250_find_match_or_unused() Sebastian Andrzej Siewior 2014-09-10 19:29 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 05/16] tty: serial: 8250_core: remove UART_IER_RDI in serial8250_stop_rx() Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-11 11:19 ` Heikki Krogerus 2014-09-11 11:19 ` Heikki Krogerus 2014-09-10 19:30 ` [PATCH 06/16] tty: serial: Add 8250-core based omap driver Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-11 11:57 ` Peter Hurley 2014-09-11 11:57 ` Peter Hurley 2014-09-11 11:57 ` Peter Hurley 2014-09-16 17:01 ` Sebastian Andrzej Siewior 2014-09-16 17:01 ` Sebastian Andrzej Siewior 2014-09-16 17:01 ` Sebastian Andrzej Siewior 2014-09-29 9:38 ` Frans Klaver 2014-09-29 9:38 ` Frans Klaver 2014-09-29 9:38 ` Frans Klaver 2014-09-29 13:27 ` Sebastian Andrzej Siewior 2014-09-29 13:27 ` Sebastian Andrzej Siewior 2014-09-29 13:34 ` Frans Klaver 2014-09-29 13:34 ` Frans Klaver 2014-09-10 19:30 ` [PATCH 07/16] tty: serial: 8250_dma: handle error on TX submit Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 08/16] tty: serial: 8250_dma: enqueue RX dma again on completion Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-11 11:17 ` Heikki Krogerus 2014-09-11 11:17 ` Heikki Krogerus 2014-09-11 11:17 ` Heikki Krogerus 2014-09-11 11:42 ` Sebastian Andrzej Siewior 2014-09-11 11:42 ` Sebastian Andrzej Siewior 2014-09-11 11:42 ` Sebastian Andrzej Siewior 2014-09-11 12:32 ` Peter Hurley 2014-09-11 12:32 ` Peter Hurley 2014-09-11 12:50 ` Sebastian Andrzej Siewior 2014-09-11 12:50 ` Sebastian Andrzej Siewior 2014-09-11 14:35 ` Peter Hurley 2014-09-11 14:35 ` Peter Hurley 2014-09-11 14:35 ` Peter Hurley 2014-09-15 17:01 ` Sebastian Andrzej Siewior 2014-09-15 17:01 ` Sebastian Andrzej Siewior 2014-09-16 16:55 ` Sebastian Andrzej Siewior 2014-09-16 16:55 ` Sebastian Andrzej Siewior 2014-09-16 16:55 ` Sebastian Andrzej Siewior 2014-09-17 12:20 ` Peter Hurley 2014-09-17 12:20 ` Peter Hurley 2014-09-17 16:25 ` Sebastian Andrzej Siewior 2014-09-17 16:25 ` Sebastian Andrzej Siewior 2014-09-17 16:25 ` Sebastian Andrzej Siewior 2014-09-29 16:15 ` Sebastian Andrzej Siewior 2014-09-29 16:15 ` Sebastian Andrzej Siewior 2014-09-11 15:11 ` Frans Klaver 2014-09-11 15:11 ` Frans Klaver 2014-09-11 15:11 ` Frans Klaver 2014-09-11 16:04 ` Sebastian Andrzej Siewior 2014-09-11 16:04 ` Sebastian Andrzej Siewior 2014-09-11 17:04 ` Frans Klaver 2014-09-11 17:04 ` Frans Klaver 2014-09-12 7:23 ` Sebastian Andrzej Siewior 2014-09-12 7:23 ` Sebastian Andrzej Siewior 2014-09-12 9:40 ` Frans Klaver 2014-09-12 9:40 ` Frans Klaver 2014-09-12 9:51 ` Sebastian Andrzej Siewior 2014-09-12 9:51 ` Sebastian Andrzej Siewior 2014-09-12 10:28 ` Frans Klaver 2014-09-12 10:28 ` Frans Klaver 2014-09-12 10:28 ` Frans Klaver 2014-09-15 16:42 ` Sebastian Andrzej Siewior 2014-09-15 16:42 ` Sebastian Andrzej Siewior 2014-09-16 9:05 ` Frans Klaver 2014-09-16 9:05 ` Frans Klaver 2014-09-16 9:05 ` Frans Klaver 2014-09-16 12:42 ` Frans Klaver 2014-09-16 12:42 ` Frans Klaver 2014-09-16 12:42 ` Frans Klaver 2014-09-16 14:23 ` Frans Klaver 2014-09-16 14:23 ` Frans Klaver 2014-09-16 14:23 ` Frans Klaver 2014-09-17 10:28 ` Frans Klaver 2014-09-17 10:28 ` Frans Klaver 2014-09-17 10:28 ` Frans Klaver 2014-09-21 20:41 ` Sebastian Andrzej Siewior 2014-09-21 20:41 ` Sebastian Andrzej Siewior 2014-09-21 20:41 ` Sebastian Andrzej Siewior 2014-09-22 9:28 ` Frans Klaver 2014-09-22 9:28 ` Frans Klaver 2014-09-22 9:28 ` Frans Klaver 2014-09-24 7:56 ` Sebastian Andrzej Siewior 2014-09-24 7:56 ` Sebastian Andrzej Siewior 2014-09-25 15:14 ` Sebastian Andrzej Siewior 2014-09-25 15:14 ` Sebastian Andrzej Siewior 2014-09-25 15:18 ` Frans Klaver 2014-09-25 15:18 ` Frans Klaver 2014-09-29 8:50 ` Frans Klaver 2014-09-29 8:50 ` Frans Klaver 2014-09-29 8:50 ` Frans Klaver 2014-09-29 9:54 ` Sebastian Andrzej Siewior 2014-09-29 9:54 ` Sebastian Andrzej Siewior 2014-09-29 10:30 ` Frans Klaver 2014-09-29 10:30 ` Frans Klaver 2014-09-29 10:30 ` Frans Klaver 2014-09-30 8:44 ` Frans Klaver 2014-09-30 8:44 ` Frans Klaver 2014-09-30 8:44 ` Frans Klaver 2014-10-02 10:27 ` Sebastian Andrzej Siewior 2014-10-02 10:27 ` Sebastian Andrzej Siewior 2014-10-02 10:27 ` Sebastian Andrzej Siewior 2014-10-13 14:55 ` Frans Klaver 2014-10-13 14:55 ` Frans Klaver 2014-10-13 14:55 ` Frans Klaver 2014-09-23 17:03 ` Peter Hurley 2014-09-23 17:03 ` Peter Hurley 2014-09-24 7:53 ` Sebastian Andrzej Siewior [this message] 2014-09-24 7:53 ` Sebastian Andrzej Siewior 2014-09-25 10:42 ` Sebastian Andrzej Siewior 2014-09-25 10:42 ` Sebastian Andrzej Siewior 2014-09-25 11:31 ` Peter Hurley 2014-09-25 11:31 ` Peter Hurley 2014-09-25 13:11 ` Sebastian Andrzej Siewior 2014-09-25 13:11 ` Sebastian Andrzej Siewior 2014-09-25 13:11 ` Sebastian Andrzej Siewior 2014-09-17 16:34 ` Sebastian Andrzej Siewior 2014-09-17 16:34 ` Sebastian Andrzej Siewior 2014-09-17 16:34 ` Sebastian Andrzej Siewior 2014-09-19 10:22 ` Heikki Krogerus 2014-09-19 10:22 ` Heikki Krogerus 2014-09-19 10:22 ` Heikki Krogerus 2014-09-19 10:58 ` Sebastian Andrzej Siewior 2014-09-19 10:58 ` Sebastian Andrzej Siewior 2014-09-19 11:25 ` Peter Hurley 2014-09-19 11:25 ` Peter Hurley 2014-09-22 7:46 ` Heikki Krogerus 2014-09-22 7:46 ` Heikki Krogerus 2014-09-25 9:24 ` Sebastian Andrzej Siewior 2014-09-25 9:24 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 10/16] tty: serial: 8250_dma: optimize the xmit path due to UART_BUG_DMA_TX Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 11/16] tty: serial: 8250_dma: keep own book keeping about RX transfers Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 12/16] tty: serial: 8250_dma: handle the UART RDI event while DMA remains idle Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-29 9:23 ` Frans Klaver 2014-09-29 9:23 ` Frans Klaver 2014-09-29 9:23 ` Frans Klaver 2014-09-10 19:30 ` [PATCH 13/16] tty: serial: 8250_dma: add pm runtime Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-29 9:26 ` Frans Klaver 2014-09-29 9:26 ` Frans Klaver 2014-09-29 9:26 ` Frans Klaver 2014-09-29 9:56 ` Sebastian Andrzej Siewior 2014-09-29 9:56 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 14/16] arm: dts: am33xx: add DMA properties for UART Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 15/16] arm: dts: dra7: " Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-10 19:30 ` [PATCH 16/16] tty: serial: 8250: omap: add dma support Sebastian Andrzej Siewior 2014-09-10 19:30 ` Sebastian Andrzej Siewior 2014-09-12 22:43 ` [PATCH 00/16 v9] omap 8250 based uart + DMA Tony Lindgren 2014-09-12 22:43 ` Tony Lindgren 2014-09-12 22:43 ` Tony Lindgren 2014-09-15 11:50 ` Sebastian Andrzej Siewior 2014-09-15 11:50 ` Sebastian Andrzej Siewior 2014-09-15 11:50 ` Sebastian Andrzej Siewior 2014-09-16 12:57 ` Sebastian Andrzej Siewior 2014-09-16 12:57 ` Sebastian Andrzej Siewior 2014-09-16 12:57 ` Sebastian Andrzej Siewior 2014-09-16 16:48 ` Tony Lindgren 2014-09-16 16:48 ` Tony Lindgren 2014-09-16 21:30 ` Tony Lindgren 2014-09-16 21:30 ` Tony Lindgren 2014-09-16 21:30 ` Tony Lindgren 2014-09-17 8:38 ` Sebastian Andrzej Siewior 2014-09-17 8:38 ` Sebastian Andrzej Siewior 2014-09-17 9:05 ` Sebastian Andrzej Siewior 2014-09-17 9:05 ` Sebastian Andrzej Siewior 2014-09-26 16:02 ` Greg KH 2014-09-26 16:02 ` Greg KH 2014-09-26 16:02 ` Greg KH
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