linux-kernel - Re: [PATCH] tty: serial: msm

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Date:	Mon, 10 Nov 2014 11:42:03 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Kevin Hilman <khilman@...nel.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	lkml <linux-kernel@...r.kernel.org>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-serial@...r.kernel.org, Olof Johansson <olof@...om.net>,
	Arnd Bergmann <arnd@...db.de>,
	Tyler Baker <tyler.baker@...aro.org>,
	Frank Rowand <frowand.list@...il.com>
Subject: Re: [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 <sboyd@...eaurora.org> wrote:
>> 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 <sboyd@...eaurora.org>
> 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 <sboyd@...eaurora.org>
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@...nel.org>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---
 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;
 

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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