From: Wolfgang Grandegger <hidden> Date: 2008-07-16 10:47:25
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
Assuming that systems using fsl-i2c should have proper platform data,
probing is disabled by default. Unfortunately, that's not the case and
various DTS files would require to be updated.
There have already been some discussion on this subject with Jean
under the following thread:
http://ozlabs.org/pipermail/linuxppc-dev/2008-July/060008.html
Please comment.
Thanks,
Wolfgang.
Signed-off-by: Wolfgang Grandegger <redacted>
---
arch/powerpc/sysdev/fsl_soc.c | 4 ++++
drivers/i2c/busses/i2c-mpc.c | 17 ++++++++++++++---
include/linux/fsl_devices.h | 1 +
3 files changed, 19 insertions(+), 3 deletions(-)
Index: linux-2.6-denx/drivers/i2c/busses/i2c-mpc.c
===================================================================
From: Jean Delvare <hidden> Date: 2008-07-16 12:05:11
Hi Wolfgang,
On Wed, 16 Jul 2008 12:47:25 +0200, Wolfgang Grandegger wrote:
quoted hunk
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
Assuming that systems using fsl-i2c should have proper platform data,
probing is disabled by default. Unfortunately, that's not the case and
various DTS files would require to be updated.
There have already been some discussion on this subject with Jean
under the following thread:
http://ozlabs.org/pipermail/linuxppc-dev/2008-July/060008.html
Please comment.
Thanks,
Wolfgang.
Signed-off-by: Wolfgang Grandegger <redacted>
---
arch/powerpc/sysdev/fsl_soc.c | 4 ++++
drivers/i2c/busses/i2c-mpc.c | 17 ++++++++++++++---
include/linux/fsl_devices.h | 1 +
3 files changed, 19 insertions(+), 3 deletions(-)
Index: linux-2.6-denx/drivers/i2c/busses/i2c-mpc.c
===================================================================
@@ -82,6 +82,7 @@ struct fsl_i2c_platform_data {/* Flags related to I2C device features */#define FSL_I2C_DEV_SEPARATE_DFSRR 0x00000001#define FSL_I2C_DEV_CLOCK_5200 0x00000002+#define FSL_I2C_DEV_PROBE 0x00000004enumfsl_usb2_operating_modes{FSL_USB2_MPH_HOST,
As a side note: in general it is not a good idea to use a template for
struct i2c_adapter. This structure is relatively large compared to the
few fields you need to set. If you insist on having a template, it
should at least be marked either const or __initdata.
--
Jean Delvare
From: Wolfgang Grandegger <hidden> Date: 2008-07-16 13:03:19
Jean Delvare wrote:
Hi Wolfgang,
On Wed, 16 Jul 2008 12:47:25 +0200, Wolfgang Grandegger wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
Assuming that systems using fsl-i2c should have proper platform data,
probing is disabled by default. Unfortunately, that's not the case and
various DTS files would require to be updated.
There have already been some discussion on this subject with Jean
under the following thread:
http://ozlabs.org/pipermail/linuxppc-dev/2008-July/060008.html
Please comment.
Thanks,
Wolfgang.
Signed-off-by: Wolfgang Grandegger <redacted>
---
arch/powerpc/sysdev/fsl_soc.c | 4 ++++
drivers/i2c/busses/i2c-mpc.c | 17 ++++++++++++++---
include/linux/fsl_devices.h | 1 +
3 files changed, 19 insertions(+), 3 deletions(-)
Index: linux-2.6-denx/drivers/i2c/busses/i2c-mpc.c
===================================================================
@@ -82,6 +82,7 @@ struct fsl_i2c_platform_data {/* Flags related to I2C device features */#define FSL_I2C_DEV_SEPARATE_DFSRR 0x00000001#define FSL_I2C_DEV_CLOCK_5200 0x00000002+#define FSL_I2C_DEV_PROBE 0x00000004enumfsl_usb2_operating_modes{FSL_USB2_MPH_HOST,
As a side note: in general it is not a good idea to use a template for
struct i2c_adapter. This structure is relatively large compared to the
few fields you need to set. If you insist on having a template, it
should at least be marked either const or __initdata.
From: Jon Smirl <hidden> Date: 2008-07-16 12:47:05
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
All this patch seems to be doing is removing class I2C_CLASS_HWMON via
a device tree flag, PROBE.
Why do you need to do this? The OF conversion patch that is working
its way through the system lets you put the address of the device into
the device tree node. Probing shouldn't be necessary at all.
--
Jon Smirl
jonsmirl@gmail.com
From: Wolfgang Grandegger <hidden> Date: 2008-07-16 13:09:24
Jon Smirl wrote:
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
All this patch seems to be doing is removing class I2C_CLASS_HWMON via
a device tree flag, PROBE.
Yep.
Why do you need to do this? The OF conversion patch that is working
its way through the system lets you put the address of the device into
the device tree node. Probing shouldn't be necessary at all.
Currently I2C_CLASS_HWMON is used for all I2C adapters and therefore
probing is done even with a proper I2C node defined in the DTS file.
That's what the patch is fixing leaving the possibility to (re-)enable
legacy probing.
For some more details you may want to have a look to Jean's mail on that
subject: http://ozlabs.org/pipermail/linuxppc-dev/2008-July/060012.html.
Wolfgang.
From: Jon Smirl <hidden> Date: 2008-07-16 14:11:22
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
Jon Smirl wrote:
quoted
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
All this patch seems to be doing is removing class I2C_CLASS_HWMON via
a device tree flag, PROBE.
Yep.
quoted
Why do you need to do this? The OF conversion patch that is working
its way through the system lets you put the address of the device into
the device tree node. Probing shouldn't be necessary at all.
Currently I2C_CLASS_HWMON is used for all I2C adapters and therefore
probing is done even with a proper I2C node defined in the DTS file. That's
what the patch is fixing leaving the possibility to (re-)enable legacy
probing.
Shouldn't we just remove I2C_CLASS_HWMON since everything can now be
explicitly described in the device tree? What is an example of a case
where we still need to probe?
From: Jon Smirl <hidden> Date: 2008-07-16 14:24:22
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
Jon Smirl wrote:
quoted
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
All this patch seems to be doing is removing class I2C_CLASS_HWMON via
a device tree flag, PROBE.
If this is implemented it shouldn't be a device tree option, it should
be a compile time option in the Kconfig system. We don't want to
pollute a platform independent device tree with Linux clutter.
--
Jon Smirl
jonsmirl@gmail.com
From: Grant Likely <hidden> Date: 2008-07-16 14:30:42
On Wed, Jul 16, 2008 at 10:24:22AM -0400, Jon Smirl wrote:
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
quoted
Jon Smirl wrote:
quoted
On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
All this patch seems to be doing is removing class I2C_CLASS_HWMON via
a device tree flag, PROBE.
If this is implemented it shouldn't be a device tree option, it should
be a compile time option in the Kconfig system. We don't want to
pollute a platform independent device tree with Linux clutter.
I'm not sure about this. It is somewhat describing the hardware. It
sounds like it is saying "hey, I've got an i2c bus here, but I don't
know what is on it; so instead of providing a set of child nodes, you
should probe this bus to find out what it has".
I don't see any problem specifying it in the device tree.
Making it a Kconfig option forces *all* i2c busses on supported
platforms into either probe or no-probe mode. Not a multiplatform
friendly solution. Heck, we've got multiple i2c busses on some chips and
it is conceivable that only one would need to be probed.
Cheers,
g.
From: Jon Smirl <hidden> Date: 2008-07-16 14:42:20
On 7/16/08, Grant Likely [off-list ref] wrote:
On Wed, Jul 16, 2008 at 10:24:22AM -0400, Jon Smirl wrote:
> On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
> > Jon Smirl wrote:
> >
> > > On 7/16/08, Wolfgang Grandegger [off-list ref] wrote:
> > >
> > > > Currently, the I2C buses are probed for HWMON I2C devices, which might
> > > > not be acceptable in same cases. This patch makes device probing
> > > > configurable through the property "probe" of the FDT I2C device node:
> > > >
> > >
> > > All this patch seems to be doing is removing class I2C_CLASS_HWMON via
> > > a device tree flag, PROBE.
>
> If this is implemented it shouldn't be a device tree option, it should
> be a compile time option in the Kconfig system. We don't want to
> pollute a platform independent device tree with Linux clutter.
I'm not sure about this. It is somewhat describing the hardware. It
sounds like it is saying "hey, I've got an i2c bus here, but I don't
know what is on it; so instead of providing a set of child nodes, you
should probe this bus to find out what it has".
Probing an i2c bus does not necessarily come to a good conclusion. The
probes for some chips can alter the states in others. People have
accidentally changed voltage settings and fried CPU chips. The process
is not well defined.
I'm not saying remove i2c probing altogether, some things require
probing like EDID data from a monitor. Since these are embedded system
I just think it is pretty unlikely that stuff like that is going to
get hooked to an i2c-mpc bus. That was behind the idea to push it
back to a compile time option.
I don't see any problem specifying it in the device tree.
Making it a Kconfig option forces *all* i2c busses on supported
platforms into either probe or no-probe mode. Not a multiplatform
friendly solution. Heck, we've got multiple i2c busses on some chips and
it is conceivable that only one would need to be probed.
Cheers,
g.
From: Timur Tabi <hidden> Date: 2008-07-16 15:01:23
Jon Smirl wrote:
Probing an i2c bus does not necessarily come to a good conclusion. The
probes for some chips can alter the states in others. People have
accidentally changed voltage settings and fried CPU chips. The process
is not well defined.
I agree. We should not be implementing any feature that encourages I2C bus
probing.
--
Timur Tabi
Linux kernel developer at Freescale
From: Grant Likely <hidden> Date: 2008-07-16 14:24:36
On Wed, Jul 16, 2008 at 12:47:25PM +0200, Wolfgang Grandegger wrote:
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
You need to add documentation to booting-without-of.txt about what the
'probe' property means. Also, 'probe' is a pretty generic term being
used in an i2c specific context. Can you prefix it with i2c or
something to protect the namespace? 'i2c-probe' perhaps?
Assuming that systems using fsl-i2c should have proper platform data,
probing is disabled by default. Unfortunately, that's not the case and
various DTS files would require to be updated.
From: Jochen Friedrich <jochen@scram.de> Date: 2008-07-16 14:48:30
Hi Grant,
On Wed, Jul 16, 2008 at 12:47:25PM +0200, Wolfgang Grandegger wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
You need to add documentation to booting-without-of.txt about what the
'probe' property means. Also, 'probe' is a pretty generic term being
used in an i2c specific context. Can you prefix it with i2c or
something to protect the namespace? 'i2c-probe' perhaps?
In i2c-cpm, I currently use the property "linux,i2c-class" to set the
i2c class directly as documented in dts-bindings/fsl/cpm_qe/cpm/i2c.txt.
We should agree on *one* method to set the i2c class.
Thanks,
Jochen
From: Wolfgang Grandegger <hidden> Date: 2008-07-16 20:20:06
Grant Likely wrote:
On Wed, Jul 16, 2008 at 12:47:25PM +0200, Wolfgang Grandegger wrote:
quoted
Currently, the I2C buses are probed for HWMON I2C devices, which might
not be acceptable in same cases. This patch makes device probing
configurable through the property "probe" of the FDT I2C device node:
i2c@3000 {
...
compatible = "fsl-i2c";
probe;
...
};
You need to add documentation to booting-without-of.txt about what the
'probe' property means. Also, 'probe' is a pretty generic term being
used in an i2c specific context. Can you prefix it with i2c or
something to protect the namespace? 'i2c-probe' perhaps?
Of course, no problem. I'm also aware of booting-without-of.txt but
first I wanted to bring up the problem-
quoted
Assuming that systems using fsl-i2c should have proper platform data,
probing is disabled by default. Unfortunately, that's not the case and
various DTS files would require to be updated.
This comment doesn't seem to be correct.
Well, maybe it's due to my bad English. What I wanted to say is that by
default probing should be disabled. But that requires various DTS files
to be fixed.
Hello, all:
I am building a Linux kernel module for PPC405EP. My developing
board is PPChameleonEVB. I am debugging with BDI2000 and GDB, and my
problem is:
In GDB, a section of the codes is disassembled to:
mfmsr r0
ori r0,r0,32768
mtmsr r0
blr
From BDI2000, I have checked that after "ori", GPR0 contains
"0x00029030". This value should be written into MSR by "mtmsr" to set EE
bit of MSR as 1, but after single step in BDI, "mtmsr" does not work as
hoped. MSR becomes "0x00000030", GPR0 becomes some weird number, and
there is "Step timeout detected". Meanwhile, the board traps into "Data
machine check in kernel mode". I also have tried "wrteei 1" instead of
the codes above, but failed again. However, those codes works well in
PPC440EP Yosemite board.
I have compared PPChameleonEVB and Yosemite. It seems the most
significant difference is for PPChameleonEVB, address translation is
enabled by default (MSR[IR, DR] = 1), while for Yosemite, it is disabled
(MSR[IR, DR] = 0). And from the error message, I think there is a
problem with PLB because PLB0_BESR becomes 0x00c00000 from 0x00000000
and PLB0_BEAR becomes 0x03066004 when machine check happens. Based on
the processor manual, the PLB0_BESR shows the PLB Timeout Error Status
and the value means the error operation is reading the processor core
DCU. The PLB0_BEAR shows the address of the access on which a bus
timeout error occurred. So I have the following questions for this
moment:
1. Is it possible or not that address translation leads to the PLB
timeout error? If that is the cause, how to fix the problem?
2. Is the address in PLB0_BEAR a memory address (real address or
effective address) or a bus address (not an address in any kind of
memory)?
3. Are there other reasons for the machine check in this situation?
4. Is it an unrecoverable hardware problem (bug) or not?
Here is the debugging log:
405EP>ti
Core number : 0
Core state : debug mode
Debug entry cause : single step
Current PC : 0xc32b1008
Current CR : 0x84000084
Current MSR : 0x00021030
Current LR : 0xc32b46c4
405EP>rd
GPR00: 00029030 c1dd9d60 c1fe7bf0 00000000
GPR04: 00000001 00000000 c32b2c8c 00000000
GPR08: c3068000 c3068000 00000001 c3062000
GPR12: 00000000 10019dd8 c32c0000 c32b0000
GPR16: 00000001 c32b0000 00000002 7ff4f670
GPR20: 00000028 c32b0000 c32b0000 10011000
GPR24: c306a000 00000000 00000000 10012c6c
GPR28: c18e4000 c32c0000 00000000 00000000
CR : 84000084 MSR: 00021030
405EP>ti
Core number : 0
Core state : debug mode
Debug entry cause : JTAG stop request
Current PC : 0xc000490c
Current CR : 0x42000082
Current MSR : 0x00000030
Current LR : 0xc001f1b8
# Step timeout detected
405EP>rd
GPR00: 03929800 c02f3e60 c3066000 000102f1
GPR04: 00005424 00000007 c0146f3c c0260000
GPR08: 00000000 c02d0000 c3062000 00000000
GPR12: 00000000 10019dd8 c32c0000 c32b0000
GPR16: 00000001 c32b0000 00000002 7ff4f670
GPR20: 00000028 c32b0000 c32b0000 10011000
GPR24: c306a000 00000000 00000000 10012c6c
GPR28: c02f0000 00000152 c3066000 c02f0000
CR : 42000082 MSR: 00000030
==========================================
Here is the error message:
Data machine check in kernel mode.
PLB0: BEAR= 0x03066004 ACR= 0x00000000 BESR= 0x00c00000
PLB0 to OPB: BEAR= 0x04000000 BESR0= 0x00000000 BESR1= 0x00000000
Oops: machine check, sig: 7 [#1]
NIP: 00002AD0 LR: 000005A0 CTR: C000CC58
REGS: c02f3f50 TRAP: 0202 Not tainted (2.6.19.2-eldk)
MSR: 00021000 <ME> CR: 24000084 XER: 20000000
TASK = c3066000[0] '' THREAD: c02d2000
GPR00: 00029030 C1DD9CA0 C3066000 C1DD9CB0 00000001 00000000 C32B2C8C
00000000
GPR08: C3068000 00000000 00021032 01DD9CA0 030661B0 10019DD8 C32C0000
C32B0000
GPR16: 00000001 C32B0000 00000002 7FF4F670 00000028 C32B0000 C32B0000
10011000
GPR24: C306A000 00000000 00000000 10012C6C C18E4000 C32C0000 00000000
00000000
NIP [00002AD0] 0x2ad0
LR [000005A0] 0x5a0
Call Trace:
Instruction dump:
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
Kernel panic - not syncing: Attempted to kill the idle task!
<0>Rebooting in 180 seconds..
Thanks a lot for advice!
Best Regards
Evangelion
July 17th, 2008
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