From: peter@hurleysoftware.com (Peter Hurley)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 03/16] tty: serial: 8250_core: read only RX if there is something in the FIFO
Date: Thu, 12 Feb 2015 14:55:38 -0500 [thread overview]
Message-ID: <54DD053A.8060905@hurleysoftware.com> (raw)
In-Reply-To: <20150212192333.GA18882@linutronix.de>
On 02/12/2015 02:23 PM, Sebastian Andrzej Siewior wrote:
> * Peter Hurley | 2015-02-12 11:32:04 [-0500]:
>
>> That said, I don't think serial8250_do_startup() is really doing that much
>> for OMAP h/w startup; open-coding what omap_8250 really needs is probably
>> < 10 loc.
>
> 10 loc? I have a few more.
:)
> serial8250_clear_fifos(),
> serial_link_irq_chain() aren't exported. serial8250_set_mctrl() can
> maybe accessed via uart_ops->set_mctrl(). Maybe I'm not removing the
> obvious not required code but here it looks better to just a BUG flag for
> the Omap.
Ok.
FWIW,
> --- a/drivers/tty/serial/8250/8250_omap.c
> +++ b/drivers/tty/serial/8250/8250_omap.c
> @@ -557,9 +557,74 @@ static int omap_8250_startup(struct uart_port *port)
>
> pm_runtime_get_sync(port->dev);
>
> - ret = serial8250_do_startup(port);
> - if (ret)
> - goto err;
> + up->mcr = 0;
> +
> + /*
> + * Clear the FIFO buffers and disable them.
> + * (they will be reenabled in set_termios())
> + */
> + serial8250_clear_fifos(up);
For omap this would just be:
serial_out(up, UART_FCR, UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
In any event, the fifo enable/disable is probably not happening since
FIFO_EN is ignored unless the divisor == 0.
> +
> + /*
> + * Clear the interrupt registers.
> + */
> + if (serial_port_in(port, UART_LSR) & UART_LSR_DR)
> + serial_port_in(port, UART_RX);
> + serial_port_in(port, UART_IIR);
> + serial_port_in(port, UART_MSR);
> +
> + retval = serial_link_irq_chain(up);
> + if (retval)
> + goto out;
omap doesn't really need the legacy irq chain handling; this could just be
request_irq().
In the 8250 split I'll be posting soon, all the irq chaining and
polling-via-timeout workarounds stays in the universal/legacy driver so
other 8250 drivers can opt-out.
> +
> + /*
> + * Now, initialize the UART
> + */
> + serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> +
--- >% ---
> + spin_lock_irqsave(&port->lock, flags);
> + /*
> + * Most PC uarts need OUT2 raised to enable interrupts.
> + */
> + if (port->irq)
> + up->port.mctrl |= TIOCM_OUT2;
> +
> + serial8250_set_mctrl(port, port->mctrl);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +
None of this is required because there is no OUT2 on omap.
---------
--- >% ----
> + /*
> + * Clear the interrupt registers again for luck, and clear the
> + * saved flags to avoid getting false values from polling
> + * routines or the previous session.
> + */
> + if (serial_port_in(port, UART_LSR) & UART_LSR_DR)
> + serial_port_in(port, UART_RX);
> + serial_port_in(port, UART_IIR);
> + serial_port_in(port, UART_MSR);
None of this is required because none of the probing is taking place.
------------
> + up->lsr_saved_flags = 0;
> + up->msr_saved_flags = 0;
> +
> + /*
> + * Request DMA channels for both RX and TX.
> + */
> + if (up->dma) {
> + retval = serial8250_request_dma(up);
> + if (retval) {
> + pr_warn_ratelimited("ttyS%d - failed to request DMA\n",
> + serial_index(port));
> + up->dma = NULL;
> + }
> + }
> +
> + /*
> + * Finally, enable interrupts. Note: Modem status interrupts
> + * are set via set_termios(), which will be occurring imminently
> + * anyway, so we don't enable them here.
> + */
> + up->ier = UART_IER_RLSI | UART_IER_RDI;
> + serial_port_out(port, UART_IER, up->ier);
> +
>
> #ifdef CONFIG_PM
> up->capabilities |= UART_CAP_RPM;
>
> Sebastian
>
next prev parent reply other threads:[~2015-02-12 19:55 UTC|newest]
Thread overview: 97+ 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 ` [PATCH 01/16] tty: serial: 8250_core: allow to set ->throttle / ->unthrottle callbacks Sebastian Andrzej Siewior
2014-09-10 19:29 ` [PATCH 02/16] tty: serial: 8250_core: add run time pm Sebastian Andrzej Siewior
2014-09-29 9:46 ` Frans Klaver
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
2015-02-09 13:34 ` Nicolas Schichan
2015-02-09 23:34 ` Peter Hurley
2015-02-10 9:32 ` Sebastian Andrzej Siewior
2015-02-10 12:04 ` Nicolas Schichan
2015-02-10 17:46 ` Peter Hurley
2015-02-11 20:01 ` Peter Hurley
2015-02-11 20:03 ` Tony Lindgren
2015-02-11 20:42 ` Peter Hurley
2015-02-12 8:45 ` Sebastian Andrzej Siewior
2015-02-12 9:40 ` Russell King - ARM Linux
2015-02-12 16:32 ` Peter Hurley
2015-02-12 19:23 ` Sebastian Andrzej Siewior
2015-02-12 19:55 ` Peter Hurley [this message]
2015-02-12 20:34 ` Sebastian Andrzej Siewior
2015-02-13 18:51 ` Sebastian Andrzej Siewior
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
2015-05-12 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 19:30 ` [PATCH 05/16] tty: serial: 8250_core: remove UART_IER_RDI in serial8250_stop_rx() Sebastian Andrzej Siewior
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
2014-09-11 11:57 ` Peter Hurley
2014-09-16 17:01 ` Sebastian Andrzej Siewior
2014-09-29 9:38 ` Frans Klaver
2014-09-29 13:27 ` Sebastian Andrzej Siewior
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 ` [PATCH 08/16] tty: serial: 8250_dma: enqueue RX dma again on completion 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
2014-09-11 11:17 ` Heikki Krogerus
2014-09-11 11:42 ` Sebastian Andrzej Siewior
2014-09-11 12:32 ` Peter Hurley
2014-09-11 12:50 ` Sebastian Andrzej Siewior
2014-09-11 14:35 ` Peter Hurley
2014-09-15 17:01 ` Sebastian Andrzej Siewior
2014-09-16 16:55 ` Sebastian Andrzej Siewior
2014-09-17 12:20 ` Peter Hurley
2014-09-17 16:25 ` Sebastian Andrzej Siewior
2014-09-29 16:15 ` Sebastian Andrzej Siewior
2014-09-11 15:11 ` Frans Klaver
2014-09-11 16:04 ` Sebastian Andrzej Siewior
2014-09-11 17:04 ` Frans Klaver
2014-09-12 7:23 ` Sebastian Andrzej Siewior
[not found] ` <20140912094010.GE28458@ci00147.xsens-tech.local>
2014-09-12 9:51 ` Sebastian Andrzej Siewior
2014-09-12 10:28 ` Frans Klaver
2014-09-15 16:42 ` Sebastian Andrzej Siewior
2014-09-16 9:05 ` Frans Klaver
2014-09-16 12:42 ` Frans Klaver
2014-09-16 14:23 ` Frans Klaver
2014-09-17 10:28 ` Frans Klaver
2014-09-21 20:41 ` Sebastian Andrzej Siewior
2014-09-22 9:28 ` Frans Klaver
2014-09-24 7:56 ` Sebastian Andrzej Siewior
2014-09-25 15:14 ` Sebastian Andrzej Siewior
2014-09-25 15:18 ` Frans Klaver
2014-09-29 8:50 ` Frans Klaver
2014-09-29 9:54 ` Sebastian Andrzej Siewior
2014-09-29 10:30 ` Frans Klaver
2014-09-30 8:44 ` Frans Klaver
2014-10-02 10:27 ` Sebastian Andrzej Siewior
2014-10-13 14:55 ` Frans Klaver
2014-09-23 17:03 ` Peter Hurley
2014-09-24 7:53 ` Sebastian Andrzej Siewior
2014-09-25 10:42 ` Sebastian Andrzej Siewior
2014-09-25 11:31 ` Peter Hurley
2014-09-25 13:11 ` Sebastian Andrzej Siewior
2014-09-17 16:34 ` Sebastian Andrzej Siewior
2014-09-19 10:22 ` Heikki Krogerus
2014-09-19 10:58 ` Sebastian Andrzej Siewior
2014-09-19 11:25 ` Peter Hurley
2014-09-22 7:46 ` Heikki Krogerus
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 ` [PATCH 11/16] tty: serial: 8250_dma: keep own book keeping about RX transfers 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
2014-09-29 9:23 ` Frans Klaver
2014-09-10 19:30 ` [PATCH 13/16] tty: serial: 8250_dma: add pm runtime Sebastian Andrzej Siewior
2014-09-29 9:26 ` Frans Klaver
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 ` [PATCH 15/16] arm: dts: dra7: " Sebastian Andrzej Siewior
2014-09-10 19:30 ` [PATCH 16/16] tty: serial: 8250: omap: add dma support Sebastian Andrzej Siewior
2014-09-12 22:43 ` [PATCH 00/16 v9] omap 8250 based uart + DMA Tony Lindgren
2014-09-15 11:50 ` Sebastian Andrzej Siewior
2014-09-16 12:57 ` Sebastian Andrzej Siewior
2014-09-16 16:48 ` Tony Lindgren
2014-09-16 21:30 ` Tony Lindgren
2014-09-17 8:38 ` Sebastian Andrzej Siewior
2014-09-17 9:05 ` Sebastian Andrzej Siewior
2014-09-26 16:02 ` Greg KH
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