diff mbox

serial: 8250_omap: provide complete custom startup & shutdown callbacks

Message ID 20150520200735.GA7790@linutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Sebastian Andrzej Siewior May 20, 2015, 8:07 p.m. UTC 
The currently in-use port->startup and port->shutdown are "okay". The
startup part for instance does the tiny omap extra part and invokes
serial8250_do_startup() for the remaining pieces. The workflow in
serial8250_do_startup() is okay except for the part where UART_RX is
read without a check if there is something to read. I tried to
workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
RX if there is something in the FIFO") but then reverted it later in
commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
only RX if there is something in the FIFO"").

This is the second attempt to get it to work on older OMAPs without
breaking other chips this time
Peter Hurley suggested to pull in the few needed lines from
serial8250_do_startup() and drop everything else that is not required
including making it simpler like using just request_irq() instead the
chain handler like it is doing now.
So lets try that.

Fixes: ca8bb4aefb93 ("serial: 8250: Revert "tty: serial: 8250_core:
       read only RX if there is something in the FIFO"")
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/8250/8250_omap.c | 82 +++++++++++++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 9 deletions(-)

Comments

Peter Hurley May 26, 2015, 2:06 p.m. UTC | #1 
On 05/20/2015 04:07 PM, Sebastian Andrzej Siewior wrote:
> The currently in-use port->startup and port->shutdown are "okay". The
> startup part for instance does the tiny omap extra part and invokes
> serial8250_do_startup() for the remaining pieces. The workflow in
> serial8250_do_startup() is okay except for the part where UART_RX is
> read without a check if there is something to read. I tried to
> workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
> RX if there is something in the FIFO") but then reverted it later in
> commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
> only RX if there is something in the FIFO"").
> 
> This is the second attempt to get it to work on older OMAPs without
> breaking other chips this time
> Peter Hurley suggested to pull in the few needed lines from
> serial8250_do_startup() and drop everything else that is not required
> including making it simpler like using just request_irq() instead the
> chain handler like it is doing now.
> So lets try that.

Thanks, Sebastian.

Reviewed-by: Peter Hurley <peter@hurleysoftware.com>

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Tony Lindgren May 26, 2015, 4:09 p.m. UTC | #2 
* Peter Hurley <peter@hurleysoftware.com> [150526 07:14]:
> On 05/20/2015 04:07 PM, Sebastian Andrzej Siewior wrote:
> > The currently in-use port->startup and port->shutdown are "okay". The
> > startup part for instance does the tiny omap extra part and invokes
> > serial8250_do_startup() for the remaining pieces. The workflow in
> > serial8250_do_startup() is okay except for the part where UART_RX is
> > read without a check if there is something to read. I tried to
> > workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
> > RX if there is something in the FIFO") but then reverted it later in
> > commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
> > only RX if there is something in the FIFO"").
> > 
> > This is the second attempt to get it to work on older OMAPs without
> > breaking other chips this time
> > Peter Hurley suggested to pull in the few needed lines from
> > serial8250_do_startup() and drop everything else that is not required
> > including making it simpler like using just request_irq() instead the
> > chain handler like it is doing now.
> > So lets try that.
> 
> Thanks, Sebastian.
> 
> Reviewed-by: Peter Hurley <peter@hurleysoftware.com>

Can we please get this into the v4.1-rc series?

It fixes the following:

Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa06a000                                                       
...                                                                                                                           
[<c04217e8>] (mem_serial_in) from [<c0425480>] (serial8250_do_startup+0xe4/0x694)
[<c0425480>] (serial8250_do_startup) from [<c0427e48>] (omap_8250_startup+0x70/0x144)
[<c0427e48>] (omap_8250_startup) from [<c0425a54>] (serial8250_startup+0x24/0x30)
[<c0425a54>] (serial8250_startup) from [<c04208e4>] (uart_startup.part.14+0x8c/0x1a0)
[<c04208e4>] (uart_startup.part.14) from [<c0420fec>] (uart_open+0xd8/0x134)
[<c0420fec>] (uart_open) from [<c0403e50>] (tty_open+0xdc/0x5e0)
[<c0403e50>] (tty_open) from [<c018f008>] (chrdev_open+0xac/0x188)

Regards,

Tony
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Greg KH May 31, 2015, 7:19 a.m. UTC | #3 
On Tue, May 26, 2015 at 09:09:26AM -0700, Tony Lindgren wrote:
> * Peter Hurley <peter@hurleysoftware.com> [150526 07:14]:
> > On 05/20/2015 04:07 PM, Sebastian Andrzej Siewior wrote:
> > > The currently in-use port->startup and port->shutdown are "okay". The
> > > startup part for instance does the tiny omap extra part and invokes
> > > serial8250_do_startup() for the remaining pieces. The workflow in
> > > serial8250_do_startup() is okay except for the part where UART_RX is
> > > read without a check if there is something to read. I tried to
> > > workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
> > > RX if there is something in the FIFO") but then reverted it later in
> > > commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
> > > only RX if there is something in the FIFO"").
> > > 
> > > This is the second attempt to get it to work on older OMAPs without
> > > breaking other chips this time
> > > Peter Hurley suggested to pull in the few needed lines from
> > > serial8250_do_startup() and drop everything else that is not required
> > > including making it simpler like using just request_irq() instead the
> > > chain handler like it is doing now.
> > > So lets try that.
> > 
> > Thanks, Sebastian.
> > 
> > Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
> 
> Can we please get this into the v4.1-rc series?
> 
> It fixes the following:
> 
> Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa06a000                                                       
> ...                                                                                                                           
> [<c04217e8>] (mem_serial_in) from [<c0425480>] (serial8250_do_startup+0xe4/0x694)
> [<c0425480>] (serial8250_do_startup) from [<c0427e48>] (omap_8250_startup+0x70/0x144)
> [<c0427e48>] (omap_8250_startup) from [<c0425a54>] (serial8250_startup+0x24/0x30)
> [<c0425a54>] (serial8250_startup) from [<c04208e4>] (uart_startup.part.14+0x8c/0x1a0)
> [<c04208e4>] (uart_startup.part.14) from [<c0420fec>] (uart_open+0xd8/0x134)
> [<c0420fec>] (uart_open) from [<c0403e50>] (tty_open+0xdc/0x5e0)
> [<c0403e50>] (tty_open) from [<c018f008>] (chrdev_open+0xac/0x188)

This is a "big" patch to come so late in the -rc cycle.  It's been
broken since 4.0, so it can't be _that_ important of a thing if no one
has been screaming about it :)

Are you willing to justify this to Linus as to why it should go in now?

thanks,

greg k-h
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Greg KH May 31, 2015, 10:09 p.m. UTC | #4 
On Tue, May 26, 2015 at 09:09:26AM -0700, Tony Lindgren wrote:
> * Peter Hurley <peter@hurleysoftware.com> [150526 07:14]:
> > On 05/20/2015 04:07 PM, Sebastian Andrzej Siewior wrote:
> > > The currently in-use port->startup and port->shutdown are "okay". The
> > > startup part for instance does the tiny omap extra part and invokes
> > > serial8250_do_startup() for the remaining pieces. The workflow in
> > > serial8250_do_startup() is okay except for the part where UART_RX is
> > > read without a check if there is something to read. I tried to
> > > workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
> > > RX if there is something in the FIFO") but then reverted it later in
> > > commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
> > > only RX if there is something in the FIFO"").
> > > 
> > > This is the second attempt to get it to work on older OMAPs without
> > > breaking other chips this time
> > > Peter Hurley suggested to pull in the few needed lines from
> > > serial8250_do_startup() and drop everything else that is not required
> > > including making it simpler like using just request_irq() instead the
> > > chain handler like it is doing now.
> > > So lets try that.
> > 
> > Thanks, Sebastian.
> > 
> > Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
> 
> Can we please get this into the v4.1-rc series?
> 
> It fixes the following:
> 
> Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa06a000                                                       
> ...                                                                                                                           
> [<c04217e8>] (mem_serial_in) from [<c0425480>] (serial8250_do_startup+0xe4/0x694)
> [<c0425480>] (serial8250_do_startup) from [<c0427e48>] (omap_8250_startup+0x70/0x144)
> [<c0427e48>] (omap_8250_startup) from [<c0425a54>] (serial8250_startup+0x24/0x30)
> [<c0425a54>] (serial8250_startup) from [<c04208e4>] (uart_startup.part.14+0x8c/0x1a0)
> [<c04208e4>] (uart_startup.part.14) from [<c0420fec>] (uart_open+0xd8/0x134)
> [<c0420fec>] (uart_open) from [<c0403e50>] (tty_open+0xdc/0x5e0)
> [<c0403e50>] (tty_open) from [<c018f008>] (chrdev_open+0xac/0x188)

In looking at it closer, this is fine, I'll queue it up for 4.1-final
now.

greg k-h
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Tony Lindgren June 1, 2015, 2:39 p.m. UTC | #5 
* Greg Kroah-Hartman <gregkh@linuxfoundation.org> [150531 15:14]:
> On Tue, May 26, 2015 at 09:09:26AM -0700, Tony Lindgren wrote:
> > * Peter Hurley <peter@hurleysoftware.com> [150526 07:14]:
> > > On 05/20/2015 04:07 PM, Sebastian Andrzej Siewior wrote:
> > > > The currently in-use port->startup and port->shutdown are "okay". The
> > > > startup part for instance does the tiny omap extra part and invokes
> > > > serial8250_do_startup() for the remaining pieces. The workflow in
> > > > serial8250_do_startup() is okay except for the part where UART_RX is
> > > > read without a check if there is something to read. I tried to
> > > > workaround it in commit 0aa525d11859 ("tty: serial: 8250_core: read only
> > > > RX if there is something in the FIFO") but then reverted it later in
> > > > commit ca8bb4aefb9 ("serial: 8250: Revert "tty: serial: 8250_core: read
> > > > only RX if there is something in the FIFO"").
> > > > 
> > > > This is the second attempt to get it to work on older OMAPs without
> > > > breaking other chips this time
> > > > Peter Hurley suggested to pull in the few needed lines from
> > > > serial8250_do_startup() and drop everything else that is not required
> > > > including making it simpler like using just request_irq() instead the
> > > > chain handler like it is doing now.
> > > > So lets try that.
> > > 
> > > Thanks, Sebastian.
> > > 
> > > Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
> > 
> > Can we please get this into the v4.1-rc series?
> > 
> > It fixes the following:
> > 
> > Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa06a000                                                       
> > ...                                                                                                                           
> > [<c04217e8>] (mem_serial_in) from [<c0425480>] (serial8250_do_startup+0xe4/0x694)
> > [<c0425480>] (serial8250_do_startup) from [<c0427e48>] (omap_8250_startup+0x70/0x144)
> > [<c0427e48>] (omap_8250_startup) from [<c0425a54>] (serial8250_startup+0x24/0x30)
> > [<c0425a54>] (serial8250_startup) from [<c04208e4>] (uart_startup.part.14+0x8c/0x1a0)
> > [<c04208e4>] (uart_startup.part.14) from [<c0420fec>] (uart_open+0xd8/0x134)
> > [<c0420fec>] (uart_open) from [<c0403e50>] (tty_open+0xdc/0x5e0)
> > [<c0403e50>] (tty_open) from [<c018f008>] (chrdev_open+0xac/0x188)
> 
> In looking at it closer, this is fine, I'll queue it up for 4.1-final
> now.

OK thanks, yes I agree this fix should have been done earlier.
But it does fix a fault for omaps.

Regards,

Tony
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diff mbox

Patch

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 9289999cb7c6..dce1a23706e8 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -562,12 +562,36 @@  static irqreturn_t omap_wake_irq(int irq, void *dev_id)
 	return IRQ_NONE;
 }
 
+#ifdef CONFIG_SERIAL_8250_DMA
+static int omap_8250_dma_handle_irq(struct uart_port *port);
+#endif
+
+static irqreturn_t omap8250_irq(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned int iir;
+	int ret;
+
+#ifdef CONFIG_SERIAL_8250_DMA
+	if (up->dma) {
+		ret = omap_8250_dma_handle_irq(port);
+		return IRQ_RETVAL(ret);
+	}
+#endif
+
+	serial8250_rpm_get(up);
+	iir = serial_port_in(port, UART_IIR);
+	ret = serial8250_handle_irq(port, iir);
+	serial8250_rpm_put(up);
+
+	return IRQ_RETVAL(ret);
+}
+
 static int omap_8250_startup(struct uart_port *port)
 {
-	struct uart_8250_port *up =
-		container_of(port, struct uart_8250_port, port);
+	struct uart_8250_port *up = up_to_u8250p(port);
 	struct omap8250_priv *priv = port->private_data;
-
 	int ret;
 
 	if (priv->wakeirq) {
@@ -580,10 +604,31 @@  static int omap_8250_startup(struct uart_port *port)
 
 	pm_runtime_get_sync(port->dev);
 
-	ret = serial8250_do_startup(port);
-	if (ret)
+	up->mcr = 0;
+	serial_out(up, UART_FCR, UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+
+	serial_out(up, UART_LCR, UART_LCR_WLEN8);
+
+	up->lsr_saved_flags = 0;
+	up->msr_saved_flags = 0;
+
+	if (up->dma) {
+		ret = serial8250_request_dma(up);
+		if (ret) {
+			dev_warn_ratelimited(port->dev,
+					     "failed to request DMA\n");
+			up->dma = NULL;
+		}
+	}
+
+	ret = request_irq(port->irq, omap8250_irq, IRQF_SHARED,
+			  dev_name(port->dev), port);
+	if (ret < 0)
 		goto err;
 
+	up->ier = UART_IER_RLSI | UART_IER_RDI;
+	serial_out(up, UART_IER, up->ier);
+
 #ifdef CONFIG_PM
 	up->capabilities |= UART_CAP_RPM;
 #endif
@@ -610,8 +655,7 @@  static int omap_8250_startup(struct uart_port *port)
 
 static void omap_8250_shutdown(struct uart_port *port)
 {
-	struct uart_8250_port *up =
-		container_of(port, struct uart_8250_port, port);
+	struct uart_8250_port *up = up_to_u8250p(port);
 	struct omap8250_priv *priv = port->private_data;
 
 	flush_work(&priv->qos_work);
@@ -621,11 +665,24 @@  static void omap_8250_shutdown(struct uart_port *port)
 	pm_runtime_get_sync(port->dev);
 
 	serial_out(up, UART_OMAP_WER, 0);
-	serial8250_do_shutdown(port);
+
+	up->ier = 0;
+	serial_out(up, UART_IER, 0);
+
+	if (up->dma)
+		serial8250_release_dma(up);
+
+	/*
+	 * Disable break condition and FIFOs
+	 */
+	if (up->lcr & UART_LCR_SBC)
+		serial_out(up, UART_LCR, up->lcr & ~UART_LCR_SBC);
+	serial_out(up, UART_FCR, UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
 
 	pm_runtime_mark_last_busy(port->dev);
 	pm_runtime_put_autosuspend(port->dev);
 
+	free_irq(port->irq, port);
 	if (priv->wakeirq)
 		free_irq(priv->wakeirq, port);
 }
@@ -974,6 +1031,13 @@  static inline int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
 }
 #endif
 
+static int omap8250_no_handle_irq(struct uart_port *port)
+{
+	/* IRQ has not been requested but handling irq? */
+	WARN_ONCE(1, "Unexpected irq handling before port startup\n");
+	return 0;
+}
+
 static int omap8250_probe(struct platform_device *pdev)
 {
 	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -1075,6 +1139,7 @@  static int omap8250_probe(struct platform_device *pdev)
 	pm_runtime_get_sync(&pdev->dev);
 
 	omap_serial_fill_features_erratas(&up, priv);
+	up.port.handle_irq = omap8250_no_handle_irq;
 #ifdef CONFIG_SERIAL_8250_DMA
 	if (pdev->dev.of_node) {
 		/*
@@ -1088,7 +1153,6 @@  static int omap8250_probe(struct platform_device *pdev)
 		ret = of_property_count_strings(pdev->dev.of_node, "dma-names");
 		if (ret == 2) {
 			up.dma = &priv->omap8250_dma;
-			up.port.handle_irq = omap_8250_dma_handle_irq;
 			priv->omap8250_dma.fn = the_no_dma_filter_fn;
 			priv->omap8250_dma.tx_dma = omap_8250_tx_dma;
 			priv->omap8250_dma.rx_dma = omap_8250_rx_dma;