From mboxrd@z Thu Jan  1 00:00:00 1970
From: florian.vaussard@epfl.ch (Florian Vaussard)
Date: Thu, 24 Jan 2013 17:50:04 +0100
Subject: [PATCH 1/2] ARM: dts: omap3-overo: Add support for pwm-leds
In-Reply-To: <5101570A.1030303@ti.com>
References: <1358963812-19947-1-git-send-email-florian.vaussard@epfl.ch>
 <1358963812-19947-2-git-send-email-florian.vaussard@epfl.ch>
 <5101510C.9050407@ti.com> <51015663.8080109@epfl.ch>
 <5101570A.1030303@ti.com>
Message-ID: <5101663C.7020301@epfl.ch>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

>> I did it at first, but the led API executes in atomic context, where the
>> pwm-twl-led driver uses i2c communication. Setting a trigger will result in a
>> kernel panic.
>
> Now that you mentioned it, this might be true.
>

[<c0013204>] (unwind_backtrace+0x0/0xec) from [<c00348ac>] 
(warn_slowpath_common+0x4c/0x64)
[<c00348ac>] (warn_slowpath_common+0x4c/0x64) from [<c00348e0>] 
(warn_slowpath_null+0x1c/0x24)
[<c00348e0>] (warn_slowpath_null+0x1c/0x24) from [<c054d384>] 
(__mutex_lock_slowpath+0x6c/0x26c)
[<c054d384>] (__mutex_lock_slowpath+0x6c/0x26c) from [<c054d590>] 
(mutex_lock+0xc/0x20)
[<c054d590>] (mutex_lock+0xc/0x20) from [<c02d740c>] 
(regmap_bulk_write+0x48/0x138)
[<c02d740c>] (regmap_bulk_write+0x48/0x138) from [<c02de2c0>] 
(twl_i2c_write+0xa4/0xf0)
[<c02de2c0>] (twl_i2c_write+0xa4/0xf0) from [<c0299e34>] 
(twl4030_pwmled_config+0x70/0x9c)
[<c0299e34>] (twl4030_pwmled_config+0x70/0x9c) from [<c029875c>] 
(pwm_config+0x5c/0x6c)
[<c029875c>] (pwm_config+0x5c/0x6c) from [<c039dc04>] 
(led_pwm_set+0x28/0x64)
[<c039dc04>] (led_pwm_set+0x28/0x64) from [<c039e27c>] 
(led_heartbeat_function+0x10c/0x134)
[<c039e27c>] (led_heartbeat_function+0x10c/0x134) from [<c004359c>] 
(call_timer_fn+0x90/0x178)
[<c004359c>] (call_timer_fn+0x90/0x178) from [<c0043994>] 
(run_timer_softirq+0x250/0x2c8)
[<c0043994>] (run_timer_softirq+0x250/0x2c8) from [<c003cf78>] 
(__do_softirq+0xf8/0x248)
[<c003cf78>] (__do_softirq+0xf8/0x248) from [<c003d154>] 
(irq_exit+0x44/0x98)
[<c003d154>] (irq_exit+0x44/0x98) from [<c000e338>] (handle_IRQ+0x68/0x8c)
[<c000e338>] (handle_IRQ+0x68/0x8c) from [<c000870c>] 
(omap3_intc_handle_irq+0x58/0x70)
[<c000870c>] (omap3_intc_handle_irq+0x58/0x70) from [<c054f8c0>] 
(__irq_svc+0x40/0x70)
Exception stack(0xc077df60 to 0xc077dfa8)

:-)

>> I am working on a patch for pwm-twl-led to defer using a workqueue right now.
>
> Great!
> The only thing I worry about is the latency we are going to get with the
> workqueue.
>

If the latency becomes critical, we can create our own workqueue.

Do we merge anyway this patchset, or do we wait until the trigger has 
been fixed?

Florian