linux-kernel - [PATCH 09/11] Blackfin Serial Driver: annotate anomalies 05000215 and 05000099

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Date:	Tue,  2 Jun 2009 03:11:38 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	uclinux-dist-devel@...ckfin.uclinux.org,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: [PATCH 09/11] Blackfin Serial Driver: annotate anomalies 05000215 and 05000099

From: Sonic Zhang <sonic.zhang@...log.com>

Add some comments for how these anomalies are addressed:

05000215 - UART TX Interrupt Masked Erroneously
We always clear ETBEI within last UART TX interrupt to end
a string.  It is always set when starting a new tx transfer.

05000099 - UART Line Status Register (UART_LSR) Bits Are Not Updated at
the Same Time
This anomaly affects driver only in POLL code where multi bits of
UART_LSR are checked. It doesn't affect current bfin_5xx.c driver.

Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
Signed-off-by: Mike Frysinger <vapier@...too.org>
---
 drivers/serial/bfin_5xx.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 854e96d..ab583ef 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -330,6 +330,11 @@ static void bfin_serial_tx_chars(struct bfin_serial_port *uart)
 		/* Clear TFI bit */
 		UART_PUT_LSR(uart, TFI);
 #endif
+		/* Anomaly notes:
+		 *  05000215 -	we always clear ETBEI within last UART TX
+		 *		interrupt to end a string. It is always set
+		 *		when start a new tx.
+		 */
 		UART_CLEAR_IER(uart, ETBEI);
 		return;
 	}
@@ -528,6 +533,11 @@ static irqreturn_t bfin_serial_dma_tx_int(int irq, void *dev_id)
 	if (!(get_dma_curr_irqstat(uart->tx_dma_channel)&DMA_RUN)) {
 		disable_dma(uart->tx_dma_channel);
 		clear_dma_irqstat(uart->tx_dma_channel);
+		/* Anomaly notes:
+		 *  05000215 -	we always clear ETBEI within last UART TX
+		 *		interrupt to end a string. It is always set
+		 *		when start a new tx.
+		 */
 		UART_CLEAR_IER(uart, ETBEI);
 		xmit->tail = (xmit->tail + uart->tx_count) & (UART_XMIT_SIZE - 1);
 		uart->port.icount.tx += uart->tx_count;
@@ -969,6 +979,10 @@ static void bfin_serial_reset_irda(struct uart_port *port)
 }
 
 #ifdef CONFIG_CONSOLE_POLL
+/* Anomaly notes:
+ *  05000099 -  Because we only use THRE in poll_put and DR in poll_get,
+ *		losing other bits of UART_LSR is not a problem here.
+ */
 static void bfin_serial_poll_put_char(struct uart_port *port, unsigned char chr)
 {
 	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
-- 
1.6.3.1

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