Hi Rob, On Mon, 5 Feb 2018 00:09:14 -0600 <r...@kernel.org> wrote:
> On Thu, Feb 01, 2018 at 04:56:08PM +0100, Bartlomiej Zolnierkiewicz wrote: > > > > Hi, > > > > On Tuesday, January 23, 2018 08:34:56 PM Kunihiko Hayashi wrote: > > > Enables 'memory-region' property referring to the memory description on > > > the reserved-memory node in case of devicetree use. > > > If there is no 'reg' property that specifies the address and size of > > > the framebuffer, the address and size written in the memory description > > > on the reserved-memory node can be used for the framebuffer. > > > > > > Furthermore, the reserved-memory node needs to have "no-map" attributes > > > because simplefb driver maps the region by ioremap_wc(). > > > > > > Signed-off-by: Kunihiko Hayashi <hayashi.kunih...@socionext.com> > > > > This needs an ACK from Rob or Mark (DT bindings Maintainers). > > > > > --- > > > .../bindings/display/simple-framebuffer.txt | 3 ++ > > > drivers/video/fbdev/simplefb.c | 32 > > > ++++++++++++++++++++++ > > > 2 files changed, 35 insertions(+) > > > > > > diff --git > > > a/Documentation/devicetree/bindings/display/simple-framebuffer.txt > > > b/Documentation/devicetree/bindings/display/simple-framebuffer.txt > > > index 5a9ce51..be5139f 100644 > > > --- a/Documentation/devicetree/bindings/display/simple-framebuffer.txt > > > +++ b/Documentation/devicetree/bindings/display/simple-framebuffer.txt > > > @@ -56,6 +56,9 @@ Optional properties: > > > framebuffer remains active. > > > > > > - display : phandle pointing to the primary display hardware node > > > +- memory-region: phandle to a node describing memory region as > > > framebuffer > > > + memory instead of reg property. The node should include > > > + 'no-map'. > > This should also state when it's appropriate to use this instead of reg. > The memory would only be reclaimed if reg is used. > > Though I'm wondering what keeps the simple fb memory from getting used > by the OS if reserved memory is not always used. Sorry that my understanding might not be correct. Since a framebuffer defined by "reserved-memory" can't be reclaimed, I've assumed such the framebuffer was dedicated and had some restrictions by device or firmware. Even in that case, You mean that we describe only "reg" directly, not go through "reserved-memory". Is that correct? It might be better to define new driver handling the dedicated framebuffer rather than using simple-fb, though, I'm not sure. --- Best Regards, Kunihiko Hayashi
