Messages in this thread | | | Date | Thu, 20 Aug 2020 06:43:47 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT |
| |
On Wed, Aug 19, 2020 at 03:57:53PM +0200, Tomasz Figa wrote: > > > Could you explain what makes you think it's unused? It's a feature of > > > the UAPI generally supported by the videobuf2 framework and relied on > > > by Chromium OS to get any kind of reasonable performance when > > > accessing V4L2 buffers in the userspace. > > > > Because it doesn't do anything except on PARISC and non-coherent MIPS, > > so by definition it isn't used by any of these media drivers. > > It's still an UAPI feature, so we can't simply remove the flag, it > must stay there as a no-op, until the problem is resolved.
Ok, I'll switch to just ignoring it for the next version.
> Also, it of course might be disputable as an out-of-tree usage, but > selecting CONFIG_DMA_NONCOHERENT_CACHE_SYNC makes the flag actually do > something on other platforms, including ARM64.
It isn't just disputable, but by kernel policies simply is not relevant.
| |