On Sun, Mar 18, 2018 at 10:09 AM, Jerome Brunet <jbrunet@xxxxxxxxxxxx> wrote: > On Sun, 2018-03-18 at 07:52 -0500, Rob Herring wrote: >> On Thu, Mar 15, 2018 at 12:55:42PM +0100, Jerome Brunet wrote: >> > The HHI register region hosts more than just clocks and needs to >> > accessed drivers other than the clock controller, such as the display >> > driver. >> > >> > This register region should be managed by syscon. It is already the case >> > on gxbb/gxl and it soon will be on axg. The clock controllers must use >> > this system controller instead of directly mapping the registers. >> >> Sounds like a kernel problem, not a DT one. > > It's a platform problem, so it has much a kernel problem (solution already > merged) as a DT problem > > DT wise, we've got two devices mapping the same region > > in arch/arm64/boot/dts/amlogic/meson-gx.dtsi: >> system-controller@0 > > which is used by the display device. > > and in arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi (same for gxl) >> clock-controller@0 > > It has worked so far because the clock controller claims the region w/o > reserving it but it remains unsafe since both device may access the same region. > The fix is to have the clock controller go through the existing syscon. We certainly want to avoid multiple nodes using the same mmio region. >> With a single child, there is really no point to this change. A single >> node can provide multiple functions. Look at nodes that are both reset >> and clock providers. > > There is more than a single user, as explained above and in the cover letter of > this series. Right, but a single node can support more than a single user (or provider). You don't have to have multiple nodes to have multiple users/providers. Rob -- 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
