From: Arnd Bergmann <arnd@arndb.de>
To: y2038@lists.linaro.org
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        linux-samsung-soc@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
        linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
        Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org
Subject: Re: [Y2038] [PATCH v2 9/9] [media] omap3isp: support 64-bit version of omap3isp_stat_data
Date: Mon, 09 Nov 2015 21:30:41 +0100
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On Monday 09 November 2015 22:09:26 Laurent Pinchart wrote:
> Hi Arnd,
> 
> Thank you for the patch.
> 
> On Thursday 17 September 2015 23:19:40 Arnd Bergmann wrote:
> > C libraries with 64-bit time_t use an incompatible format for
> > struct omap3isp_stat_data. This changes the kernel code to
> > support either version, by moving over the normal handling
> > to the 64-bit variant, and adding compatiblity code to handle
> > the old binary format with the existing ioctl command code.
> > 
> > Fortunately, the command code includes the size of the structure,
> > so the difference gets handled automatically.
> 
> We plan to design a new interface to handle statistics in V4L2. That API 
> should support proper 64-bit timestamps out of the box, and will be 
> implemented by the OMAP3 ISP driver. Userspace should then move to it. I 
> wonder if it's worth it to fix the existing VIDIOC_OMAP3ISP_STAT_REQ ioctl 
> given that I expect it to have a handful of users at most.

We still need to do something to the driver. The alternative would
be to make the existing ioctl command optional at kernel compile-time
so we can still build the driver once we remove the 'struct timeval'
definition. That patch would add slightly less complexity here
but also lose functionality.

As my patch here depends on the struct v4l2_timeval I introduced in
an earlier patch of the series, we will have to change it anyways,
but I'd prefer to keep the basic idea. Let's get back to this one
after the v4l_buffer replacement work is done.

	Arnd
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