[OpenWrt-Devel] [PATCH 1/1] [kernel] Fix kmod-v4l2 modules have missing symbols due to lack of clk support

Daniel Dickinson openwrt at daniel.thecshore.com
Wed Aug 19 19:30:28 EDT 2015

Your patch resolves the issue of compiling - I have not yet tested the 
functionality of the resulting v4l module.  I suspect the disadvantage 
of this patch is that it will silently fail to work for the types of 
devices (DV primarily) that depend on clock support whereas my patch 
omits building code/modules for devices that depend on clock support a 
kernel config option that prevents building useless modules (although I 
realized the DV_SUPPORT should depend on CLK_COMMON since that's the 
whole reason for making that a config option) and (and of course 
#ifdef's out the code and dependencies on clk support when it's not 



On 2015-08-15 10:34 AM, Hauke Mehrtens wrote:
> On 08/02/2015 04:34 PM, Daniel Dickinson wrote:
>> The v4l kernel modules fail to compile on latest kernels due to a new
>> dependency on a clock source.  Since most routers won't have a suitable
>> clock source, I have added a kernel config option that omits the functionality
>> that requires the clock source.
>> That means v4l modules in OpenWrt can't support DV devices (DV requires
>> the clock source support) but unless clock source support was addded to
>> OpenWrt the other alternative is to drop v4l altogether).
>> Signed-off-by: Daniel Dickinson <openwrt at daniel.thecshore.com>
>> ---
>>   package/kernel/linux/modules/video.mk              |   3 +-
>>   ...avoid-clk-for-devices-that-do-not-need-it.patch | 348 +++++++++++++++++++++
>>   2 files changed, 350 insertions(+), 1 deletion(-)
>>   create mode 100644 target/linux/generic/patches-4.1/273-v4l-avoid-clk-for-devices-that-do-not-need-it.patch
> The build problem of ar71xx was fixed here:
> https://dev.openwrt.org/changeset/46572
> The arch code did not export all the clk functions needed, but claimed
> to do so. Is your patch needed with r46572 any more? When an arch really
> does not support clocks it a driver would use the static inline
> functions doing nothing instead.
> Hauke
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