From: khilman@ti•com (Kevin Hilman)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v6 09/16] OMAP2+: UART: Add runtime pm support for omap-serial driver
Date: Thu, 13 Oct 2011 14:22:13 -0700 [thread overview]
Message-ID: <87obxkio3e.fsf@ti.com> (raw)
In-Reply-To: <CAAL8m4yrXo4KRYxXxWECU99B6--FCMBDFUbNk+vsBV0Jnt0bcg@mail.gmail.com> (Govindraj's message of "Thu, 13 Oct 2011 06:58:48 +0530")
Govindraj <govindraj.ti@gmail•com> writes:
> On Thu, Oct 13, 2011 at 5:36 AM, Kevin Hilman <khilman@ti•com> wrote:
>> "Govindraj.R" <govindraj.raja@ti•com> writes:
>>
>> [...]
>>
>>> Use device_may_wakeup to check whether uart has wakeup capabilities
>>> and then enable uart runtime usage for the uart.
>>
>> Curious about what happens when device_may_wakeup() is not set during
>> device init.
>>
>> [...]
>>
>>> @@ -1305,6 +1363,16 @@ static int serial_omap_probe(struct platform_device *pdev)
>>> ? ? ? ? ? ? ? up->uart_dma.rx_dma_channel = OMAP_UART_DMA_CH_FREE;
>>> ? ? ? }
>>>
>>> + ? ? pm_runtime_use_autosuspend(&pdev->dev);
>>> + ? ? pm_runtime_set_autosuspend_delay(&pdev->dev,
>>> + ? ? ? ? ? ? ? ? ? ? OMAP_UART_AUTOSUSPEND_DELAY);
>>> +
>>> + ? ? pm_runtime_irq_safe(&pdev->dev);
>>> + ? ? if (device_may_wakeup(&pdev->dev)) {
>>> + ? ? ? ? ? ? pm_runtime_enable(&pdev->dev);
>>
>> So if device_may_wakeup() is false, runtime PM is not enabled, then...
>>
>>> + ? ? ? ? ? ? pm_runtime_get_sync(&pdev->dev);
>>
>> ...this get doesn't happen, and the first register access causes a crash.
>
> Actually no crash, clocks will left enabled from boot up (hwmod_no_reset/idle)
> that are idled and enabled back here.
>
> Since hwmod_idle is binded here later ([PATCH v6 15/16]),
IMO, That's not a very maintainable solution.
What happens when when someone fixes serial.c to only set
HWMOD_INIT_NO_IDLE on the console UART? or if we fix things so we don't
need INIT_NO_IDLE anymore? Then this will crash.
Driver code should not make assumptions like this about what device init
code is or isn't doing.
Kevin
next prev parent reply other threads:[~2011-10-13 21:22 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 11:01 [PATCH v6 01/16] OMAP2+: hwmod: Add API to enable IO ring wakeup Govindraj.R
2011-09-30 11:01 ` [PATCH v6 02/16] OMAP2+: hwmod: Add API to check IO PAD wakeup status Govindraj.R
2011-10-01 14:33 ` Rajendra Nayak
2011-10-03 5:00 ` Govindraj
2011-10-03 5:23 ` Rajendra Nayak
2011-10-03 5:56 ` Govindraj
2011-10-10 22:24 ` Kevin Hilman
2011-10-11 6:17 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 03/16] OMAP2+: UART: cleanup + remove uart pm specific API Govindraj.R
2011-09-30 11:01 ` [PATCH v6 04/16] OMAP2+: UART: cleanup 8250 console driver support Govindraj.R
2011-10-04 21:42 ` Kevin Hilman
2011-10-05 6:54 ` Govindraj
2011-10-05 18:42 ` Kevin Hilman
2011-10-06 8:16 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 05/16] OMAP2+: UART: Cleanup part of clock gating mechanism for uart Govindraj.R
2011-10-10 22:30 ` Kevin Hilman
2011-10-11 6:45 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 06/16] OMAP2+: UART: Remove certain feilds from omap_uart_state struct Govindraj.R
2011-10-10 23:31 ` Kevin Hilman
2011-10-12 10:25 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 07/16] OMAP2+: UART: Add default mux for all uarts Govindraj.R
2011-10-05 19:04 ` Kevin Hilman
2011-10-06 8:21 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 08/16] OMAP2+: UART: Store certain reg values to port structure Govindraj.R
2011-10-10 23:58 ` Kevin Hilman
2011-10-11 13:21 ` Govindraj
2011-09-30 11:01 ` [PATCH v6 09/16] OMAP2+: UART: Add runtime pm support for omap-serial driver Govindraj.R
2011-10-10 23:42 ` Kevin Hilman
2011-10-12 10:37 ` Govindraj
2011-10-10 23:56 ` Kevin Hilman
2011-10-12 10:35 ` Govindraj
2011-10-13 0:06 ` Kevin Hilman
2011-10-13 1:28 ` Govindraj
2011-10-13 21:22 ` Kevin Hilman [this message]
2011-10-14 12:32 ` Govindraj
2011-10-14 17:04 ` Kevin Hilman
2011-10-14 18:29 ` Govindraj
2011-10-01 13:41 ` [PATCH v6 01/16] OMAP2+: hwmod: Add API to enable IO ring wakeup Rajendra Nayak
2011-10-03 15:10 ` Vishwanath Sripathy
2011-10-04 21:03 ` Kevin Hilman
2011-10-05 11:57 ` Rajendra Nayak
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