Re: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter for debugSS module control

2013-04-10 Thread Tony Lindgren 
* Hiremath, Vaibhav hvaib...@ti.com [130409 22:16]:
 Agreed on making it as a module.
 
 But do you think we should allow it as a loadable module (M) as well, 
 as user will loose Connectivity to JTAG during boot.
 Another perspective here would be, user can insert the module and
 Get JTAG connectivity, which also seems ok to me.

Yes both ways should be doable.
 
 Can you also confirm on having command line argument? I think
 We can only live with DT based approach, right?

Well I doubt that anybody wants to keep it permanently enabled
because of the power consumption and blocking of PM states, so
an additional cmdline might make sense.

It would be nice to have it most of the time built-in but disable
itself unless something debug is specified in the cmdline.

Maybe the JTAG driver can detect when the cable is connected?
Or maybe that would be only when there's clock coming over
JTAG?

Regards,

Tony
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RE: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter for debugSS module control

2013-04-09 Thread Hiremath, Vaibhav 

 -Original Message-
 From: Tony Lindgren [mailto:t...@atomide.com]
 Sent: Monday, April 08, 2013 11:00 PM
 To: Hiremath, Vaibhav
 Cc: linux-omap@vger.kernel.org; khil...@linaro.org; p...@pwsan.com;
 Nayak, Rajendra; linux-arm-ker...@lists.infradead.org
 Subject: Re: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter
 for debugSS module control
 
 Hi,
 
 * hvaib...@ti.com hvaib...@ti.com [130304 03:40]:
  From: Vaibhav Hiremath hvaib...@ti.com
 
  Currently there is no clean mechanism to control debugSS module and
  you have to always keep clocks enabled, either,
 
  - By enabling it during boot as part of clk_init function.
  Or
  - By having HWMOD_INIT_NO_IDLE flag in hwmod data.
 
  Based on the discussion,
  http://www.mail-archive.com/linux-omap@vger.kernel.org/msg81771.html
 
  This patch introduces new kernel parameter omap_debugss_en,
  which will allow user to control debugSS module enable/disable
  part during boot-time.
 
 I suggest you just make this part into a standard DT only
 device driver. That way the command line parsing and clock
 enabling can happen the normal way.
 

That’s good idea, as we are moving towards DT only boot support.
Also, are you suggesting to have both command-line param and DT
Property for this?


 Is there any reason why this could not be a loadable module?
 

Because we want to keep it enabled before late_initcall. As part of 
late_initcall
Clock/hwmod framework will start disabling unused modules, which will impact the
Debugs as well. Consider the case where this debugss is loaded as a module, the 
user
Will loose the JTAG connection until the module is loaded; and once module is
Loaded, he has to again re-connect to the debugss.


With only DT option the code will look like below, is this what you also have 
in your mind -

arch/arm/boot/dts/am33xx.dtsi:

debugss: debugss@4b00 {
compatible = ti,debugss;
ti,hwmods = debugss;
reg = 0x4b00 100;
status = disabled;/* User need to enable it if he need 
JTAG connectivity*/
};


arch/arm/mach-omap2/debugss.c:

static int __init _omap2_debugss_enable(void)
{
struct device_node *np;

np = of_find_matching_node(oh_name);
if (!node || ! of_device_is_available()) {
pr_err(debugss device is not found\n);
return -ENODEV;
}
...
hwmod lookup./setup/enable along with optional clock enable.
...

}
device_initcall(_omap2_debugss_enable);

Thanks,
Vaibhav
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Re: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter for debugSS module control

2013-04-09 Thread Tony Lindgren 
* Hiremath, Vaibhav hvaib...@ti.com [130409 01:12]:
  From: Tony Lindgren [mailto:t...@atomide.com]
  
  I suggest you just make this part into a standard DT only
  device driver. That way the command line parsing and clock
  enabling can happen the normal way.
  
 
 That’s good idea, as we are moving towards DT only boot support.
 Also, are you suggesting to have both command-line param and DT
 Property for this?
 
 
  Is there any reason why this could not be a loadable module?
  
 
 Because we want to keep it enabled before late_initcall. As part of 
 late_initcall
 Clock/hwmod framework will start disabling unused modules, which will impact 
 the
 Debugs as well. Consider the case where this debugss is loaded as a module, 
 the user
 Will loose the JTAG connection until the module is loaded; and once module is
 Loaded, he has to again re-connect to the debugss.

It will get run before late_initcall if compiled in. Sounds
like there are no issues also make it work as a loadable module
as needed.
 
 With only DT option the code will look like below, is this what you also have 
 in your mind -
 
 arch/arm/boot/dts/am33xx.dtsi:
 
   debugss: debugss@4b00 {
   compatible = ti,debugss;
   ti,hwmods = debugss;
   reg = 0x4b00 100;
   status = disabled;/* User need to enable it if he need 
 JTAG connectivity*/
   };


 arch/arm/mach-omap2/debugss.c:
 
   static int __init _omap2_debugss_enable(void)
   {
   struct device_node *np;
   
   np = of_find_matching_node(oh_name);
   if (!node || ! of_device_is_available()) {
   pr_err(debugss device is not found\n);
   return -ENODEV;
   }
   ...
   hwmod lookup./setup/enable along with optional clock enable.
   ...
 
   }
   device_initcall(_omap2_debugss_enable);

It should be all standard device driver stuff. I'd make it just
regular module_platform_driver and only initialize it earlier if
compiled in.

Regards,

Tony


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RE: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter for debugSS module control

2013-04-09 Thread Hiremath, Vaibhav 

 -Original Message-
 From: Tony Lindgren [mailto:t...@atomide.com]
 Sent: Tuesday, April 09, 2013 10:05 PM
 To: Hiremath, Vaibhav
 Cc: linux-omap@vger.kernel.org; khil...@linaro.org; p...@pwsan.com;
 Nayak, Rajendra; linux-arm-ker...@lists.infradead.org
 Subject: Re: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter
 for debugSS module control
 
 * Hiremath, Vaibhav hvaib...@ti.com [130409 01:12]:
   From: Tony Lindgren [mailto:t...@atomide.com]
  
   I suggest you just make this part into a standard DT only
   device driver. That way the command line parsing and clock
   enabling can happen the normal way.
  
 
  That’s good idea, as we are moving towards DT only boot support.
  Also, are you suggesting to have both command-line param and DT
  Property for this?
 
 
   Is there any reason why this could not be a loadable module?
  
 
  Because we want to keep it enabled before late_initcall. As part of
 late_initcall
  Clock/hwmod framework will start disabling unused modules, which will
 impact the
  Debugs as well. Consider the case where this debugss is loaded as a
 module, the user
  Will loose the JTAG connection until the module is loaded; and once
 module is
  Loaded, he has to again re-connect to the debugss.
 
 It will get run before late_initcall if compiled in. Sounds
 like there are no issues also make it work as a loadable module
 as needed.
 
Agreed on making it as a module.

But do you think we should allow it as a loadable module (M) as well, 
as user will loose Connectivity to JTAG during boot.
Another perspective here would be, user can insert the module and
Get JTAG connectivity, which also seems ok to me.

Can you also confirm on having command line argument? I think
We can only live with DT based approach, right?

Thanks,
Vaibhav 

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Re: [RFC PATCH 3/3] ARM: OMAP2+: Add command line parameter for debugSS module control

2013-04-08 Thread Tony Lindgren 
Hi,

* hvaib...@ti.com hvaib...@ti.com [130304 03:40]:
 From: Vaibhav Hiremath hvaib...@ti.com
 
 Currently there is no clean mechanism to control debugSS module and
 you have to always keep clocks enabled, either,
 
 - By enabling it during boot as part of clk_init function.
 Or
 - By having HWMOD_INIT_NO_IDLE flag in hwmod data.
 
 Based on the discussion,
 http://www.mail-archive.com/linux-omap@vger.kernel.org/msg81771.html
 
 This patch introduces new kernel parameter omap_debugss_en,
 which will allow user to control debugSS module enable/disable
 part during boot-time.

I suggest you just make this part into a standard DT only
device driver. That way the command line parsing and clock
enabling can happen the normal way.

Is there any reason why this could not be a loadable module?

Regards,

Tony
 
 Signed-off-by: Vaibhav Hiremath hvaib...@ti.com
 Cc: Kevin Hilman khil...@linaro.org
 Cc: Paul Walmsley p...@pwsan.com
 Cc: Tony Lindgren t...@atomide.com
 ---
 Tested on
   - AM335x based EVM and BeagleBone platforms
 
  Documentation/kernel-parameters.txt |3 +
  arch/arm/mach-omap2/Makefile|2 +-
  arch/arm/mach-omap2/debugss.c   |   80 
 +++
  3 files changed, 84 insertions(+), 1 deletions(-)
  create mode 100644 arch/arm/mach-omap2/debugss.c
 
 diff --git a/Documentation/kernel-parameters.txt 
 b/Documentation/kernel-parameters.txt
 index 6c72381..bf1c822 100644
 --- a/Documentation/kernel-parameters.txt
 +++ b/Documentation/kernel-parameters.txt
 @@ -2051,6 +2051,9 @@ bytes respectively. Such letter suffixes can also be 
 entirely omitted.
   For example, to override I2C bus2:
   omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
 
 + omap_debugss_en [OMAP] Enable Debug Sub-System module required
 + for JTAG debugging.
 +
   oprofile.timer= [HW]
   Use timer interrupt instead of performance counters
 
 diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
 index d1156cf..aaf5cc2 100644
 --- a/arch/arm/mach-omap2/Makefile
 +++ b/arch/arm/mach-omap2/Makefile
 @@ -5,7 +5,7 @@
  # Common support
  obj-y := id.o io.o control.o mux.o devices.o fb.o serial.o gpmc.o timer.o 
 pm.o \
common.o gpio.o dma.o wd_timer.o display.o i2c.o hdq1w.o omap_hwmod.o \
 -  omap_device.o sram.o
 +  omap_device.o sram.o debugss.o
 
  omap-2-3-common  = irq.o
  hwmod-common = omap_hwmod.o \
 diff --git a/arch/arm/mach-omap2/debugss.c b/arch/arm/mach-omap2/debugss.c
 new file mode 100644
 index 000..b45bf2c
 --- /dev/null
 +++ b/arch/arm/mach-omap2/debugss.c
 @@ -0,0 +1,80 @@
 +/*
 + * debugss.c: Debug Sus-System related code goes in here
 + *
 + * Copyright (C) {2013} Texas Instruments Incorporated - http://www.ti.com/
 + *
 + * This file is automatically generated from the AM33XX hardware databases.
 + * This program is free software; you can redistribute it and/or
 + * modify it under the terms of the GNU General Public License as
 + * published by the Free Software Foundation version 2.
 + *
 + * This program is distributed as is WITHOUT ANY WARRANTY of any
 + * kind, whether express or implied; without even the implied warranty
 + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 + * GNU General Public License for more details.
 + */
 +
 +#include linux/init.h
 +#include linux/err.h
 +#include linux/clk.h
 +
 +#include omap_hwmod.h
 +
 +static bool is_debugss_en;
 +
 +/**
 + * omap_debugss_en - Enable debugss clock/module based on user config
 + *
 + * During kernel bootup, omap2 hwmod framework will disable all the
 + * unused/unclaimed modules, which in turn also disables debugss module.
 + * This breaks any further debugging capability provided by HW.
 + *
 + *
 + * Introduce early param which allows user to enable clock/module -
 + *
 + *   omap_debugss_en (For all OMAP2 architectures)
 + *
 + * Please note that, with this command-line param, module always remain
 + * enabled.
 + */
 +static int __init omap_debugss_en(char *str)
 +{
 + is_debugss_en = true;
 + return 0;
 +}
 +early_param(omap_debugss_en, omap_debugss_en);
 +
 +static int __init _omap2_debugss_enable(void)
 +{
 + const char oh_name[10] = debugss;
 + struct omap_hwmod *oh;
 + int ret;
 +
 + if (is_debugss_en) {
 + struct omap_hwmod_opt_clk *oc;
 + int i;
 +
 + oh = omap_hwmod_lookup(oh_name);
 + if (!oh) {
 + pr_err(debugss device not found\n);
 + return 0;
 + }
 +
 + /* Make sure that hwmod internal data structures are setup */
 + ret = omap_hwmod_setup_one(oh_name);
 + if (ret) {
 + pr_err(failed to setup hwmod for %s\n, oh_name);
 + return 0;
 + }
 + /* Enable