On Wed, Mar 14, 2018 at 6:23 AM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > On 09/03/18 20:27, Benoit Parrot wrote: > >>> Is logical plane a h/w concept? >> >> It does represent a hardware resource. > > Logical plane is not a hw concept, it just describes a group of one or > two HW planes. Then again, in the context of 2k+ displays, two HW planes > must always be used together, so that way it could be considered a > single HW resource. > >>> Really, I'm skeptical that any of this belongs in DT. For example, >>> can't you figure out you need 2 physical planes whenever your >>> panel/timing width is greater than 2048? >> >> As stated in the description I added above, we cannot have resources >> exposed to user-space which can "disappear" dynamically. >> Doing so would break user-space applications which rely on these >> resources. Isn't this the point of atomic mode setting? If you have 2 planes free, then you can support the mode, otherwise you fail. How would a plane be in use if you are doing modesetting unless it is on another display? > The question is, if not in DT, then where? I agree that this is not > exactly describing the HW. But it can't be done dynamically either (or > at least we have not figured out a way). And it must be user configurable. If you are plugging in a monitor, doesn't it have to be dynamic? > Module parameters are an option, but it would be somewhat difficult to > give all this information there. And also, if your board has a 2k+ > display, you must have these configurations given to the driver, it's > not optional. Can't you look at the panel size on boot or module load and determine if you need to combine planes or not. The main difference I see is that the driver would have to figure out which planes to use rather than DT telling it what planes to use. Is deciding which planes a hard problem? > > And while it's perhaps stretching the definitions a bit, I guess one > could argue that this describes the HW in a way: it describes how the HW > resources must be used if you have a display of 2k+ width, and is not as > such related to Linux or DRM. > > Tomi > > -- > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
