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* [PATCH 1/9] omap3/4: uart: fix full-fifo write abort
@ 2010-02-18  8:59 Santosh Shilimkar
  2010-02-18  8:59 ` [PATCH 2/9] omap2/3/4: ioremap omap_globals module Santosh Shilimkar
  2010-02-19  5:25 ` [PATCH 1/9] omap3/4: uart: fix full-fifo write abort Shilimkar, Santosh
  0 siblings, 2 replies; 25+ messages in thread
From: Santosh Shilimkar @ 2010-02-18  8:59 UTC (permalink / raw)
  To: linux-arm-kernel

This patch is addition to the already merged commit on non-empty
uart fifo read abort. "ce13d4716a276f4331d78ba28a5093a63822ab95"

OMAP3630 and OMAP4430 UART IP blocks have a restriction on TX FIFO
too. If you try to write to the tx fifo when it is full, the system aborts.

This can be easily reproducible by not suppressing interconnect errors or
long duration testing where continuous prints over console from multiple
threads. This patch is addressing the issue by ensuring that write is
not issued while fifo is full. A timeout is added to avoid any hang
on fifo-full for 10 mS which is unlikely case.

Patch is validated on OMAP3630 and OMAP4 SDP.

V2 version removed the additional 1 uS on every TX as per
Tony's suggestion

Signed-off-by: Woodruff Richard <r-woodruff2@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
CC: Ghorai Sukumar <s-ghorai@ti.com>
---
 arch/arm/mach-omap2/serial.c |   31 ++++++++++++++++++++++++++++---
 1 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 5f3035e..b79bc89 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -23,6 +23,7 @@
 #include <linux/serial_reg.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/delay.h>
 
 #include <plat/common.h>
 #include <plat/board.h>
@@ -160,6 +161,13 @@ static inline unsigned int serial_read_reg(struct plat_serial8250_port *up,
 	return (unsigned int)__raw_readb(up->membase + offset);
 }
 
+static inline void __serial_write_reg(struct uart_port *up, int offset,
+		int value)
+{
+	offset <<= up->regshift;
+	__raw_writeb(value, up->membase + offset);
+}
+
 static inline void serial_write_reg(struct plat_serial8250_port *p, int offset,
 				    int value)
 {
@@ -620,6 +628,20 @@ static unsigned int serial_in_override(struct uart_port *up, int offset)
 	return __serial_read_reg(up, offset);
 }
 
+static void serial_out_override(struct uart_port *up, int offset, int value)
+{
+	unsigned int status, tmout = 10000;
+
+	status = __serial_read_reg(up, UART_LSR);
+	while (!(status & UART_LSR_THRE)) {
+		/* Wait up to 10ms for the character(s) to be sent. */
+		if (--tmout == 0)
+			break;
+		udelay(1);
+		status = __serial_read_reg(up, UART_LSR);
+	}
+	__serial_write_reg(up, offset, value);
+}
 void __init omap_serial_early_init(void)
 {
 	int i;
@@ -721,11 +743,14 @@ void __init omap_serial_init_port(int port)
 	 * omap3xxx: Never read empty UART fifo on UARTs
 	 * with IP rev >=0x52
 	 */
-	if (cpu_is_omap44xx())
+	if (cpu_is_omap44xx()) {
 		uart->p->serial_in = serial_in_override;
-	else if ((serial_read_reg(uart->p, UART_OMAP_MVER) & 0xFF)
-			>= UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV)
+		uart->p->serial_out = serial_out_override;
+	} else if ((serial_read_reg(uart->p, UART_OMAP_MVER) & 0xFF)
+			>= UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV) {
 		uart->p->serial_in = serial_in_override;
+		uart->p->serial_out = serial_out_override;
+	}
 }
 
 /**
-- 
1.6.0.4

^ permalink raw reply related	[flat|nested] 25+ messages in thread

end of thread, other threads:[~2010-02-24  4:09 UTC | newest]

Thread overview: 25+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-02-18  8:59 [PATCH 1/9] omap3/4: uart: fix full-fifo write abort Santosh Shilimkar
2010-02-18  8:59 ` [PATCH 2/9] omap2/3/4: ioremap omap_globals module Santosh Shilimkar
2010-02-18  8:59   ` [PATCH 3/9] omap4: sdma: Enable the idle modes on omap4 Santosh Shilimkar
2010-02-18  8:59     ` [PATCH 4/9] omap: sdma: Limit the secure reserve channel fix for omap3 Santosh Shilimkar
2010-02-18  8:59       ` [PATCH 5/9] omap4: Fix omap_type() for omap4 Santosh Shilimkar
2010-02-18  8:59         ` [PATCH 6/9] omap3/4: Remove overlapping mapping of L4_WKUP io space Santosh Shilimkar
2010-02-18  8:59           ` [PATCH 7/9] omap4: Add auto-generated irq and dma headers Santosh Shilimkar
2010-02-18  8:59             ` [PATCH 8/9] omap4: Use dma line defines from dma-44xx.h Santosh Shilimkar
2010-02-18  8:59               ` [PATCH 9/9] omap4: Use irq line defines from irq-44xx.h Santosh Shilimkar
2010-02-22 22:13               ` [PATCH 8/9] omap4: Use dma line defines from dma-44xx.h Tony Lindgren
2010-02-18 17:23             ` [PATCH 7/9] omap4: Add auto-generated irq and dma headers Paul Walmsley
2010-02-18 17:33               ` Shilimkar, Santosh
2010-02-19  5:10               ` Shilimkar, Santosh
2010-02-18 17:35   ` [PATCH 2/9] omap2/3/4: ioremap omap_globals module Paul Walmsley
2010-02-18 22:24   ` Kevin Hilman
2010-02-19  5:13     ` Shilimkar, Santosh
2010-02-19  5:25 ` [PATCH 1/9] omap3/4: uart: fix full-fifo write abort Shilimkar, Santosh
2010-02-22 21:39   ` Tony Lindgren
2010-02-22 23:07     ` Tony Lindgren
2010-02-23  5:42       ` Shilimkar, Santosh
2010-02-23  7:19       ` Shilimkar, Santosh
2010-02-23 23:12         ` Tony Lindgren
2010-02-24  4:09           ` Shilimkar, Santosh
2010-02-23 16:17     ` Shilimkar, Santosh
2010-02-23 18:54       ` Tony Lindgren

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