On Fri, Feb 23, 2018 at 04:48:58PM +0000, Liviu Dudau wrote: > On Fri, Feb 23, 2018 at 11:43:29AM -0500, Sean Paul wrote: > > On Fri, Feb 23, 2018 at 11:25:11AM -0500, Rob Clark wrote: > > > On Fri, Feb 23, 2018 at 10:59 AM, Sean Paul <seanpaul@xxxxxxxxxxxx> wrote: > > > > > > > > Have we considered hiding writeback behind a client cap instead? > > > > > > It is kinda *almost* unneeded, since the connector reports itself as > > > disconnected. > > > > > > I'm not sure what the reason was to drop the cap, but I think it would > > > be better to have a cap so WB connectors don't show up in, for ex, > > > xrandr > > > > Yeah, the disconnected hack is kind of gross, IMO. I hate to introduce churn in > > the patch series given that it was initially introduced with the client cap. > > Haha, that's the reverse of Daniel's position: > > https://lists.freedesktop.org/archives/dri-devel/2016-October/120519.html Yeah, it happens :(. I don't think it's a dealbreaker either way, it just seems awkward to expose a connector which is "disconnected", but available for use. I don't think we have any other connectors which are supposed to be used in this state. > > > > > There are also cases where we might want to make writeback unavailable, such as > > when content protection is enabled. In those cases, it's conceivable that we > > might want to use disconnected as a signal to u/s. I suppose we could also just > > fail the check, so most of this is just academic. > > Not sure what other hardware out there does, but on Mali DP's case you > would be outputing the protected content by putting the display > processor in secure mode, which automatically disables writeback for us. > Or to put in another way, you don't need a writeback framebuffer if you > are in non-secure mode as you can get access to the framebuffer used for > the plane anyway. Yeah, I was mostly thinking about the case where you might have HDCP enabled on the HDMI connector and be able to slurp up the content via a writeback. However if the buffer is not secure in the first place, then it's already accessible in userspace so I don't think that writeback presents a new security hole. /me needs to get HDCP out of his head. Sean > > Best regards, > Liviu > > > > > Sean > > > > > > > > > > BR, > > > -R > > > > -- > > Sean Paul, Software Engineer, Google / Chromium OS > > -- > ==================== > | I would like to | > | fix the world, | > | but they're not | > | giving me the | > \ source code! / > --------------- > ¯\_(ツ)_/¯ -- Sean Paul, Software Engineer, Google / Chromium OS -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
