On 04/17/2014 12:23 AM, Mauro Carvalho Chehab wrote: > Em Mon, 10 Mar 2014 13:20:49 +0100 > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > >> From: Hans Verkuil <hans.verkuil@xxxxxxxxx> >> >> Convert the saa7134 driver to vb2. >> >> Note that while this uses the vb2-dma-sg version, the VB2_USERPTR mode is >> disabled. The DMA hardware only supports DMAing full pages, and in the >> USERPTR memory model the first and last scatter-gather buffer is almost >> never a full page. >> >> In practice this means that we can't use the VB2_USERPTR mode. > > Why not? Provided that the buffer is equal or bigger than the number of > pages required by saa7134, that should be OK. > > All the driver needs to do is to check if the USERPTR buffer condition is met, > returning an error otherwise (and likely printing a msg at dmesg). Yuck. Well, I'll take a look at this. It has in my view the same problem as abusing USERPTR to pass pointers to physically contiguous memory: yes, it 'supports' USERPTR, but it has additional requirements which userspace has no way of knowing or detecting. It's really not USERPTR at all, it is PAGE_ALIGNED_USERPTR. Quite different. I would prefer that you have to enable it explicitly through e.g. a module option. That way you can still do it, but you really have to know what you are doing. > I suspect that this change will break some userspace programs used > for video surveillance equipment. > >> This has been tested with raw video, compressed video, VBI, radio, DVB and >> video overlays. >> >> Unfortunately, a vb2 conversion is one of those things you cannot split >> up in smaller patches, it's all or nothing. This patch switches the whole >> driver over to vb2, using the vb2 ioctl and fop helper functions. > > Not quite true. This patch contains lots of non-vb2 stuff, like: > - Coding Style fixes; > - Removal of res_get/res_set/res_free; > - Functions got moved from one place to another one. I will see if there is anything sensible that I can split up. I'm not aware of any particular coding style issues, but I'll review it. The removal of the resource functions is not something I can split up. It is replaced by the resource handling that's built into the vb2 helper functions. Regards, Hans > > It is really hard to review it, as is, as the real changes are mixed with > the above code cleanups/changes. > > Please split this patch in a way that it allows reviewing the changes > there. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
