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>
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 @@
/* 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 @@
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 @@
}
#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;
