Message-ID: <515AB67A.8010206@amarulasolutions.com>
Date:	Tue, 02 Apr 2013 12:44:10 +0200
From:	Michael Trimarchi <michael@...rulasolutions.com>
To:	Sourav Poddar <sourav.poddar@...com>
CC:	Kevin Hilman <khilman@...aro.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Felipe Balbi <balbi@...com>, Rajendra nayak <rnayak@...com>,
	tony@...mide.com, rmk+kernel@....linux.org.uk,
	linux-serial@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH/Resend 2/2] arm: mach-omap2: prevent UART console idle
 on suspend while using "no_console_suspend"

Hi

On 02/04/13 12:39, Sourav Poddar wrote:
> Hi,
> On Tuesday 02 April 2013 03:36 PM, Michael Trimarchi wrote:
>> Hi
>>
>> On 02/04/13 11:50, Sourav Poddar wrote:
>>> Hi Kevin,
>>> On Wednesday 20 March 2013 05:36 PM, Sourav Poddar wrote:
>>>> Realised the list  to whom the patch was send got dropped. Ccing them all..
>>>> On Wednesday 20 March 2013 05:18 PM, Sourav Poddar wrote:
>>>>> Hi Kevin,
>>>>> On Tuesday 19 March 2013 12:24 AM, Kevin Hilman wrote:
>>>>>> Sourav Poddar<sourav.poddar@...com>   writes:
>>>>>>
>>>>>>> With dt boot, uart wakeup after suspend is non functional on omap4/5 while using
>>>>>>> "no_console_suspend" in the bootargs. With "no_console_suspend" used, od->flags
>>>>>>> should be ORed with "OMAP_DEVICE_NO_IDLE_ON_SUSPEND", thereby not allowing the console
>>>>>>> to idle in the suspend path. For non-dt case, this was taken care by platform data.
>>>>>>>
>>>>>>> Tested on omap5430evm, omap4430sdp.
>>>>>>>
>>>>>>> Cc: Santosh Shilimkar<santosh.shilimkar@...com>
>>>>>>> Cc: Felipe Balbi<balbi@...com>
>>>>>>> Cc: Rajendra nayak<rnayak@...com>
>>>>>>> Signed-off-by: Sourav Poddar<sourav.poddar@...com>
>>>>>> This patch creates a dependency between omap_device (generic,
>>>>>> device-independent code) and a specific driver (UART.)
>>>>>>
>>>>>> If you need to do something like this that's DT boot specific, then
>>>>>> we probably need some late initcall in serial.c to handle this.  It does
>>>>>> not belong in omap_device.
>>>>>>
>>>>> The following function "omap_device_disable_idle_on_suspend(pdev)" should only
>>>>> be called once the omap device has been build, which in the case of device tree is
>>>>> done in omap_device.c file. Moreover, the above call should be executed conditionally
>>>>> and should depend on the following two parameter.
>>>>>
>>>>> [1]  a. Whether "no_console_suspend" is set and
>>>>>       b.  the device build is a console uart.
>>>>>
>>>>> When I look closely into the serial.c file, I realised that
>>>>> "core_initcall(omap_serial_early_init)" gets called irrespective
>>>>> of dt/non dt boot and will take care of most of the stuff(checking whether
>>>>> "no_console_suspend" is used and which uart is used as a console uart) which the
>>>>> $subject patch is proposing.
>>>>>
>>>>> But the problem is that we need to exchange the parsed information
>>>>> from serial.c to the omap_device file for the condtional execution of
>>>>> "omap_device_disable_idle_on_suspend"
>>>>>
>>>>> In this case,
>>>>> from "serial.c" we need
>>>>>      1. no_console_suspend = true
>>>>>      2. strcpy(console_name, oh_name), where oh_name corresponds to the console uart.
>>>>>
>>>>> then in "omap_device.c" do
>>>>>      if (no_console_suspend&&  !strcmp(oh->name, console_name))
>>>>>                  omap_device_disable_idle_on_suspend(pdev);
>>>>>
>>>>> Please correct if I am understanding it incorrectly.
>>>>>
>>>>> If the above understanding looks good to you, is there a way we can make this
>>>>> exchange of information happen between serial.c and omap_device.c file?
>>> Any input on this?
>>> As I explained earlier, that there is a need to parse information in serial.c and use that in
>>> omap_device.c only after the device is build.
>>>
>>> Below is the patch (inlined) which further explains my point. The patch is "just for the
>>> idea" I am trying to express.
>>> I have used extern variables to exchange information between serial.c and omap_device.c.
>>> Is there is a better way, we can do this "information exchange" without using extern variables?
>>>
>>>
>>> -----
>>> From: Sourav Poddar<sourav.poddar@...com>
>>> Date: Wed, 13 Mar 2013 20:32:36 +0530
>>> Subject: [RFC/PATCH] arm: mach-omap2: prevent UART console idle on suspend while using "no_console_suspend"
>>>
>>> With dt boot on omap5, uart wakeup after suspend is non functional while using
>>> "no_console_suspend" in the bootargs. With "no_console_suspend" used, od->flags
>>> should be ORed with "OMAP_DEVICE_NO_IDLE_ON_SUSPEND", thereby not allowing the console
>>> to idle in the suspend path. For non-dt case, this was taken care by platform data.
>>>
>>> Tested on omap5430evm, omap4430sdp.
>>>
>>> Signed-off-by: Sourav Poddar<sourav.poddar@...com>
>>> ---
>>> The problem is I need to use couple of "extern variables" which
>>> can be used in the omap_device file, after the device is built from dt.
>>>
>>>   arch/arm/mach-omap2/omap_device.c |    7 ++++++-
>>>   arch/arm/mach-omap2/serial.c      |    4 +++-
>>>   2 files changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
>>> index e065daa..f4ebf9f 100644
>>> --- a/arch/arm/mach-omap2/omap_device.c
>>> +++ b/arch/arm/mach-omap2/omap_device.c
>>> @@ -96,6 +96,9 @@
>>>   #define USE_WAKEUP_LAT            0
>>>   #define IGNORE_WAKEUP_LAT        1
>>>
>>> +extern u8 no_console_suspend;
>>> +extern char console_uart_name[];
>>> +
>>>   static int omap_early_device_register(struct platform_device *pdev);
>>>
>>>   static struct omap_device_pm_latency omap_default_latency[] = {
>>> @@ -372,7 +375,9 @@ static int omap_device_build_from_dt(struct platform_device *pdev)
>>>               r->name = dev_name(&pdev->dev);
>>>       }
>>>
>>> -    if (of_get_property(node, "ti,no_idle_on_suspend", NULL))
>>> +    if (no_console_suspend&&  !strcmp(oh->name, console_uart_name))
>>> +        omap_device_disable_idle_on_suspend(pdev);
>>> +    else if (of_get_property(node, "ti,no_idle_on_suspend", NULL))
>>>           omap_device_disable_idle_on_suspend(pdev);
>> Why do not use some flags instead of external variable?
>>
>>
> That flag also need to be set in serial.c and used in omap_device.c.
> Moreover, I am doing a strcmp so I need a console uart name to be passed
> from serial.c to omap_device.c

Just an idea, I didn't check the code

if (oh->flags & OMAP_FORCE_DISABLE_IDLE_ON_SUSPEND || of_get_property(node, "ti,no_idle_on_suspend", NULL))
	omap_device_disable_idle_on_suspend(pdev);

And I don't know if you can set such flags in serial.c

Michael


>>>       pdev->dev.pm_domain =&omap_device_pm_domain;
>>> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>>> index 037e691..f841ab5 100644
>>> --- a/arch/arm/mach-omap2/serial.c
>>> +++ b/arch/arm/mach-omap2/serial.c
>>> @@ -63,8 +63,9 @@ struct omap_uart_state {
>>>   static LIST_HEAD(uart_list);
>>>   static u8 num_uarts;
>>>   static u8 console_uart_id = -1;
>>> -static u8 no_console_suspend;
>>>   static u8 uart_debug;
>>> +u8 no_console_suspend;
>>> +char console_uart_name[MAX_UART_HWMOD_NAME_LEN];
>>>
>>>   #define DEFAULT_RXDMA_POLLRATE        1    /* RX DMA polling rate (us) */
>>>   #define DEFAULT_RXDMA_BUFSIZE        4096    /* RX DMA buffer size */
>>> @@ -199,6 +200,7 @@ static int __init omap_serial_early_init(void)
>>>                   "%s%d", OMAP_SERIAL_NAME, uart->num);
>>>
>>>           if (cmdline_find_option(uart_name)) {
>>> +            strcpy(console_uart_name, oh_name);
>>>               console_uart_id = uart->num;
>>>
>>>               if (console_loglevel>= 10) {
>> Michael
> ~Sourav
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