Re: [PATCH 2/2] tty/serial: at91: add a fallback option to determineuart/usart property
From: Nicolas Ferre
Date: Thu Oct 17 2013 - 04:17:21 EST
On 16/10/2013 22:14, Greg Kroah-Hartman :
On Tue, Oct 15, 2013 at 11:19:18AM +0200, Nicolas Ferre wrote:
On 14/10/2013 15:59, Jean-Christophe PLAGNIOL-VILLARD :
On 10:43 Thu 10 Oct , Nicolas Ferre wrote:
On older SoC, the "name" field is not filled in the register map.
Fix the way to figure out if the serial port is an uart or an usart for these
older products (with corresponding properties).
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
drivers/tty/serial/atmel_serial.c | 19 ++++++++++++++++++-
include/linux/atmel_serial.h | 1 +
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 6b0f75e..c7d99af 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -99,6 +99,7 @@ static void atmel_stop_rx(struct uart_port *port);
#define UART_PUT_RTOR(port,v) __raw_writel(v, (port)->membase + ATMEL_US_RTOR)
#define UART_PUT_TTGR(port, v) __raw_writel(v, (port)->membase + ATMEL_US_TTGR)
#define UART_GET_IP_NAME(port) __raw_readl((port)->membase + ATMEL_US_NAME)
+#define UART_GET_IP_VERSION(port) __raw_readl((port)->membase + ATMEL_US_VERSION)
/* PDC registers */
#define UART_PUT_PTCR(port,v) __raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -1503,6 +1504,7 @@ static void atmel_get_ip_name(struct uart_port *port)
{
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
int name = UART_GET_IP_NAME(port);
+ u32 version;
int usart, uart;
/* usart and uart ascii */
usart = 0x55534152;
@@ -1517,7 +1519,22 @@ static void atmel_get_ip_name(struct uart_port *port)
dev_dbg(port->dev, "This is uart\n");
atmel_port->is_usart = false;
} else {
- dev_err(port->dev, "Not supported ip name, set to uart\n");
+ /* fallback for older SoCs: use version field */
+ version = UART_GET_IP_VERSION(port);
+ switch (version) {
+ case 0x302:
+ case 0x10213:
+ dev_dbg(port->dev, "This version is usart\n");
+ atmel_port->is_usart = true;
+ break;
+ case 0x203:
+ case 0x10202:
+ dev_dbg(port->dev, "This version is uart\n");
+ atmel_port->is_usart = false;
+ break;
+ default:
+ dev_err(port->dev, "Not supported ip name nor version, set to uart\n");
it's not really an error a dev_warn is more oppropriate
As we are already in -rc5 and that these fixes are critical for at91
platforms, I will not re-spin another patch just for this.
Moreover, I have the feeling that if we end up in this case, it
means that we are in big troubles because the usart/uart included in
the product triggering this log is not known (I recall that newer
products do not have to hit these lines of code).
With these 2 reasons, I prefer to keep my patch like it is.
Greg, can you consider taking these two patches as regression fixes
for 3.12 (with Tested-by tag from Thomas)?
Is this really a regression from 3.11?
Yes it is. Commit id that I am referring to in patch 1/2
(055560b04a8cd063aea916fd083b7aec02c2adb8) hit the mainline in 3.12-rc
time-frame.
What's the worry about waiting
for 3.13-rc1, getting this correct, and then backporting them to the
3.12-stable trees?
It will break all older at91 in 3.12-final. Moreover, I do think that
the actual patches are bringing an incorrect solution and I do not plan
to have a better one (which one?) for 3.13...
I'd prefer that, so, please clean this up properly and resend it, with
the tested-by: lines and I'll queue them up for 3.13-rc1.
I do not know what to cleanup. Anyway, tell me if you want that I resend
the series of 2 patches with the "Tested-by" tag included.
Bye,
--
Nicolas Ferre
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