From: s.nawrocki@samsung•com (Sylwester Nawrocki)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH V2 6/7] ARM: EXYNOS5: Add the bus clock for FIMD
Date: Tue, 24 Jul 2012 11:13:20 +0200 [thread overview]
Message-ID: <500E6730.1030805@samsung.com> (raw)
In-Reply-To: <000501cd6951$2aa24f00$7fe6ed00$%han@samsung.com>
Hi,
On 07/24/2012 06:02 AM, Jingoo Han wrote:
>>>>>>>> I wonder fimd clock has any dependency with DP
>>>>>>> FIMD pixel clock is necessary to enable DP.
>>>>>> So then, i think DP driver also should control FIMD pixel clock.
>>>>>> Do you have any patch or plan for it?
>>>>> Um, I don't think so.
>>>>> Because, DP cannot work by itself.
>>>>> In order to use DP, FIMD should be enabled.
>>>>>
>>>>> If FIMD is enabled, FIMD pixel clock is enabled;
>>>>> therefore, DP driver does not need to control FIMD pixel clock.
>>>> Why does DP driver have FIMD driver dependency? Also for this, it needs
>>>> FIMD driver is probed earlier then DP driver. We cannot decide driver
>>>> probe order if they are same level drivers and itself is weird
>>>> condition. Although there is hardware dependency, DP and FIMD driver
>>>> don't have any code relations. They are each other drivers. But DP
>>>> needs FIMD pixel clock and because the clock can be control at the
>>>> several drivers and the clock framework exists for that, then i think
>>>> it's better DP driver also control FIMD pixel clock.
>>>>
>>>>> In my opinion, adding config dependency would be better, such as FB_S3C or DRM_EXYNOS_FIMD.
>>>> I think this is not solution. How do you ensure FIMD driver is probed
>>>> earlier than DP driver? Even if it's possible, when FIMD driver only
>>>> controls pixel clock, DP driver will execute any operations regardless
>>>> status of FIMD pixel clock, so if FIMD driver turns off pixel clock,
>>>> then DP will occur any error.
>>> late_initcall can ensure DP driver is probed later.
>>
>> I'm not sure late_initcall solution is good. It must choose at the last
>> if there isn't other way really.
>
>
> late_initcall is already used by many drivers.
> If you have any good idea, please, suggest it.
I agree with Mr. Shim here. using initcall doesn't look like a solution
to this issue. Neither compile time dependency is of much help.
The S3C framebuffer driver can be used as a loadable module, how
would initcalls be supposed to work then ?
Some notify mechanisms or deferred probing could be used, to make sure one
of drivers is initialized before the other.
--
Thanks,
Sylwester
next prev parent reply other threads:[~2012-07-24 9:13 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-18 5:57 [PATCH V2 0/7] Add device tree based discovery support for drm-fimd Leela Krishna Amudala
2012-07-18 5:57 ` [PATCH V2 1/7] ARM: SAMSUNG: add additional registers and SFR definitions for writeback Leela Krishna Amudala
2012-07-18 6:51 ` Marek Szyprowski
2012-07-18 7:09 ` Ajay kumar
2012-07-20 10:09 ` Sylwester Nawrocki
2012-07-19 12:43 ` Leela Krishna Amudala
2012-07-20 6:45 ` Marek Szyprowski
2012-07-18 11:05 ` Tomasz Figa
2012-07-19 13:00 ` Leela Krishna Amudala
2012-07-19 13:35 ` Tomasz Figa
2012-07-20 2:21 ` Jingoo Han
2012-07-20 2:59 ` Leela Krishna Amudala
2012-07-20 9:49 ` Tomasz Figa
2012-07-20 10:00 ` Sylwester Nawrocki
2012-07-20 11:07 ` Leela Krishna Amudala
2012-07-20 12:54 ` Sylwester Nawrocki
2012-07-22 22:35 ` Jingoo Han
2012-07-18 5:57 ` [PATCH V2 2/7] ARM: EXYNOS5: add machine specific support for backlight Leela Krishna Amudala
2012-07-18 5:57 ` [PATCH V2 3/7] ARM: EXYNOS5: add machine specific support for LCD Leela Krishna Amudala
2012-07-18 6:45 ` Marek Szyprowski
2012-07-19 13:21 ` Leela Krishna Amudala
2012-07-20 6:31 ` Marek Szyprowski
2012-07-24 16:02 ` Leela Krishna Amudala
2012-07-20 7:17 ` Joonyoung Shim
2012-07-18 5:57 ` [PATCH V2 4/7] ARM: EXYNOS: Adding DRM platform device Leela Krishna Amudala
2012-07-20 7:33 ` Joonyoung Shim
2012-07-18 5:57 ` [PATCH V2 5/7] ARM: EXYNOS: add device tree based discovery support for FIMD Leela Krishna Amudala
2012-07-20 7:39 ` Joonyoung Shim
2012-07-18 5:57 ` [PATCH V2 6/7] ARM: EXYNOS5: Add the bus clock " Leela Krishna Amudala
2012-07-23 8:34 ` Joonyoung Shim
2012-07-23 9:54 ` Joonyoung Shim
2012-07-23 23:14 ` Jingoo Han
2012-07-23 23:45 ` Joonyoung Shim
2012-07-23 23:48 ` Jingoo Han
2012-07-23 23:55 ` Jingoo Han
2012-07-24 1:55 ` Joonyoung Shim
2012-07-24 2:15 ` Jingoo Han
2012-07-24 3:06 ` Joonyoung Shim
2012-07-24 4:02 ` Jingoo Han
2012-07-24 9:13 ` Sylwester Nawrocki [this message]
2012-07-18 5:57 ` [PATCH V2 7/7] ARM: EXYNOS5: Set parent clock to fimd Leela Krishna Amudala
2012-07-23 8:41 ` Joonyoung Shim
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