Hi, Arnd!
Arnd Bergmann schrieb:
> On Monday 19 November 2007, Clemens Koller wrote:
>> Unable to handle kernel paging request for data at address 0x00000000
>> Faulting instruction address: 0xc018f03c
>> Oops: Kernel access of bad area, sig: 11 [#1]
>> MPC85xx ADS
>> Modules linked in:
>> NIP: c018f03c LR: c018f00c CTR: c00127b4
>> REGS: c0821cf0 TRAP: 0300 Not tainted (2.6.24-rc2-ge6a5c27f)
>> MSR: 00029000 <EE,ME> CR: 42022088 XER: 20000000
>> DEAR: 00000000, ESR: 00000000
>> TASK = c081e000[1] 'swapper' THREAD: c0820000
>> GPR00: b1000000 c0821da0 c081e000 c0833e10 00000004 c0821d80 c03d3064
c05eea80
>> GPR08: 00000200 00000002 0000002a 13ab6680 82022042 00000000 c03318a4
c033188c
>> GPR16: c0331908 c03318f0 c03a0e30 c0331930 c033191c 007fff00 0ffeccbc
c03a0000
>> GPR24: c0821dc4 00000000 00000003 c0934cf8 cffffba8 00000000 c0833e00
c07fdc6c
>> NIP [c018f03c] of_platform_serial_probe+0x118/0x1e4
>> LR [c018f00c] of_platform_serial_probe+0xe8/0x1e4
>> Call Trace:
>
> Ok, that is a NULL pointer access, probably somewhere in the
> of_platform_serial_setup that can be inlined. Please post the
> device tree entries for your serial ports so we can see what
> goes wrong there.
The device tree is the default one which comes with the kernel:
paulus.git/arch/powerpc/boot/dts/mpc8540ads.dts
which contains:
[EMAIL PROTECTED] {
device_type = "serial";
compatible = "ns16550";
reg = <4500 100>; // reg base, size
clock-frequency = <0>; // should we fill in in uboot?
interrupts = <2a 2>;
interrupt-parent = <&mpic>;
};
[EMAIL PROTECTED] {
device_type = "serial";
compatible = "ns16550";
reg = <4600 100>; // reg base, size
clock-frequency = <0>; // should we fill in in uboot?
interrupts = <2a 2>;
interrupt-parent = <&mpic>;
};
> One potential problem that I can see is a missing 'current-speed'
> property in your tree, which would cause this behavior.
That's correct. Should be fixed in all .dts' ?
> It looks
> like many device trees set this, but it is not required by all
> bindings.
How should someone know, when it's really needed and when not?
> If that's the case, the patch below should fix your
> problem, but you probably want to set the current-speed anyway,
> according to your boot loader settings.
I think there was no need to set it again, because of: console=ttyS0,115200
But I'll verify...
> --- a/drivers/serial/of_serial.c
> +++ b/drivers/serial/of_serial.c
> @@ -56,7 +56,8 @@ static int __devinit of_platform_serial_setup(struct
of_device *ofdev,
> port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
> | UPF_FIXED_PORT;
> port->dev = &ofdev->dev;
> - port->custom_divisor = *clk / (16 * (*spd));
> + if (spd)
> + port->custom_divisor = *clk / (16 * (*spd));
>
> return 0;
> }
>
Ack! However, I changed it similar to the available code.
No idea what's better here. At least it should tell the user:
Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ sharing enabled
serial8250.0: ttyS0 at MMIO 0xe0004500 (irq = 42) is a 16550A
console [ttyS0] enabled
serial8250.0: ttyS1 at MMIO 0xe0004600 (irq = 42) is a 16550A
of_serial e0004500.serial: no current-speed property set
of_serial e0004600.serial: no current-speed property set
Patch attached.
Regards,
--
Clemens Koller
__________________________________
R&D Imaging Devices
Anagramm GmbH
Rupert-Mayer-Straße 45/1
Linhof Werksgelände
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Warn user when current-speed property isn't set and exit.
Signed-off-by: Clemens Koller <[EMAIL PROTECTED]>
CC: Arnd Bergmann <[EMAIL PROTECTED]>
diff --git a/drivers/serial/of_serial.c b/drivers/serial/of_serial.c
index a64d858..e035cb2 100644
--- a/drivers/serial/of_serial.c
+++ b/drivers/serial/of_serial.c
@@ -36,6 +36,10 @@ static int __devinit of_platform_serial_setup(struct
of_device *ofdev,
memset(port, 0, sizeof *port);
spd = of_get_property(np, "current-speed", NULL);
clk = of_get_property(np, "clock-frequency", NULL);
+ if (!spd) {
+ dev_warn(&ofdev->dev, "no current-speed property set\n");
+ return -ENODEV;
+ }
if (!clk) {
dev_warn(&ofdev->dev, "no clock-frequency property set\n");
return -ENODEV;
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