Re: [RESEND PATCH] serial: samsung: fix device name
From: Paulius Zaleckas
Date: Fri Sep 24 2010 - 12:38:09 EST
On 09/24/2010 09:57 AM, Darius Augulis wrote:
Hi,
On Fri, Sep 24, 2010 at 2:40 AM, Ben Dooks<ben-linux@xxxxxxxxx> wrote:
On 23/09/10 20:15, Darius Augulis wrote:
Swap device and driver names in serial/samsung.c
This is far too short, please see the notes below on trying
to make this more informative.
Signed-off-by: Darius Augulis<augulis.darius@xxxxxxxxx>
---
This patch was submitted about 3 months ago, but still not merged.
There was another similar patch from Joonyoung Shim
<jy0922.shim@xxxxxxxxxxx> and was discussed here:
http://marc.info/?l=linux-serial&m=127416101222281&w=2.
Joonyoung Shim acked my patch and other people on ARM mailing list
acked it. The maintainer, Ben Dooks, still not responding for
a long time. Another maintainer, Kukjin Kim, refused to merge
it without Ben's review.
I would like to ask somebody pick up this bugfix.
I belive last time this was brought up I asked about the affect
this has on the userspace. The following issues would be helpful
or essential to have noted in the header about the effect of this.
- Does it change the /dev name of the device? if so I would thinl
carefully about applying it, as it would be a change in the way
that userspace sees the kernel.
It does - now devices are named /dev/s3c2410_serial, and patch changes
its name to /dev/ttySAC
- Does it change the kernel output itself? A note on what diffeences
can be seen in things like dmesg would be helpful.
It does. Serial driver reports device names when probing, so there
will appear ttySACx instead of
s3c2410_serialx.
- Are there any other side effects
- Why is this a bug? Maybe the previous points will explain what is
going on, but if not, then a reasonably concise description of
what is going on here.
This is bug, because of several points:
1. Because it contradicts kernel documentation. Please read
Documentation/arm/Samsung-S3C24XX/Overview.txt line 196.
This should be enough to apply this patch.
2. Because s3c2410_serial isn't correct name for serial device node.
It's name of Samsung serial driver.
3. Because now almost all userspace systems workaround it by creating symlink
/dev/ttySACx> /dev/s3c2410_serialx and only then put some getty on
created symlink, not on original device.
Systems which don't create this symlink, fail to boot at all, because
of wrong console name. Good example is Buildroot.
I had similar issue with buildroot too, because in /etc/securetty it is
defained as ttySAC0
4. For console in kernel boot command line you must enter console=ttySACx.
Why it sould be different in userspace?
For me it seems taht this bug was not noticed earlier, because most embedded
systems were using static device nodes and ttySACx was used in these cases.
drivers/serial/samsung.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/serial/samsung.c b/drivers/serial/samsung.c
index b1156ba..25c0d0f 100644
--- a/drivers/serial/samsung.c
+++ b/drivers/serial/samsung.c
@@ -883,10 +883,10 @@ static struct uart_ops s3c24xx_serial_ops = {
static struct uart_driver s3c24xx_uart_drv = {
.owner = THIS_MODULE,
- .dev_name = "s3c2410_serial",
+ .driver_name = "s3c2410_serial",
.nr = CONFIG_SERIAL_SAMSUNG_UARTS,
.cons = S3C24XX_SERIAL_CONSOLE,
- .driver_name = S3C24XX_SERIAL_NAME,
+ .dev_name = S3C24XX_SERIAL_NAME,
.major = S3C24XX_SERIAL_MAJOR,
.minor = S3C24XX_SERIAL_MINOR,
};
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