Blackfin Serial Driver: annotate anomalies 05000215 and 05000099

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@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 854e96dfb070..ab583ef3a305 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;