Date:	Tue, 2 Apr 2013 16:09:53 +0530
From:	Sourav Poddar <sourav.poddar@...com>
To:	Michael Trimarchi <michael@...rulasolutions.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 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
>>       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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