[PATCH] tty: serial: msm_serial: Use DT aliases

On 11/10/2014 10:54 AM, Kevin Hilman wrote:

On Wed, Oct 22, 2014 at 5:33 PM, Stephen Boyd [off-list ref] wrote:

quoted

We rely on probe order of this driver to determine the line number for
the uart port. This makes it impossible to know the line number
when these devices are populated via DT. Use the DT alias
mechanism to assign the line based on the aliases node.

Signed-off-by: Stephen Boyd <redacted>

FYI... this patch hit linux-next and caused multiple boot failures on
qcom platforms[1] as of next-20141110.  I'm assuming this is because
the corresponding DTS changes have not hit linux-next yet.

Kevin

[1] http://status.armcloud.us/boot/?qcom

Hmm the intention was to make it optional so that dts changes aren't
necessary unless you want deterministic numbering. I screwed that up
badly :/ Thanks for finding this.

Greg, can you also apply this patch or squash it into the bad one?

----8<-----

From: Stephen Boyd <redacted>
Subject: [PATCH] tty: serial: msm_serial: Don't required DT aliases

If there isn't a DT alias then of_alias_get_id() will return
-ENODEV. This will cause the msm_serial driver to fail probe,
when we want to keep the previous behavior where we generated a
dynamic line number at probe time. Restore this behavior by
generating a dynamic id if the line number is still negative
after checking for an alias or (in the non-DT case) looking at the
.id field of the platform device.

Reported-by: Kevin Hilman <khilman@kernel.org>
Signed-off-by: Stephen Boyd <redacted>
---
 drivers/tty/serial/msm_serial.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 09364dd8cf3a..d1bc6b6cbc70 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c

@@ -1046,14 +1046,14 @@ static int msm_serial_probe(struct platform_device *pdev)
 	const struct of_device_id *id;
 	int irq, line;
 
-	if (pdev->id == -1)
-		pdev->id = atomic_inc_return(&msm_uart_next_id) - 1;
-
 	if (pdev->dev.of_node)
 		line = of_alias_get_id(pdev->dev.of_node, "serial");
 	else
 		line = pdev->id;
 
+	if (line < 0)
+		line = atomic_inc_return(&msm_uart_next_id) - 1;
+
 	if (unlikely(line < 0 || line >= UART_NR))
 		return -ENXIO;
 

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