Hi Simon, On Thu, Jun 13, 2019 at 12:02:46PM +0200, Simon Horman wrote: > On Wed, Jun 12, 2019 at 03:15:56PM +0300, Laurent Pinchart wrote: > > On Wed, Jun 12, 2019 at 09:37:14AM +0200, Geert Uytterhoeven wrote: > >> On Sun, Jun 9, 2019 at 1:11 PM Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> wrote: > >>> It is necessary to reset the LVDS Interface according to display on/off. > >>> Therefore, this patch adds CPG reset properties in DU device node > >>> for the R8A77995 SoC. > >>> > >>> This patch was inspired by a patch in the BSP by Takeshi Kihara <takeshi.kihara.df@xxxxxxxxxxx>. > >>> > >>> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx> > >> > >> Thanks for your patch! > >> > >>> --- a/arch/arm64/boot/dts/renesas/r8a77995.dtsi > >>> +++ b/arch/arm64/boot/dts/renesas/r8a77995.dtsi > >>> @@ -1001,6 +1001,8 @@ > >>> clocks = <&cpg CPG_MOD 724>, > >>> <&cpg CPG_MOD 723>; > >>> clock-names = "du.0", "du.1"; > >>> + resets = <&cpg 724>, <&cpg 724>; > >>> + reset-names = "du.0", "du.1"; > >> > >> These are not the LVDS resets, but the (shared) DU channel resets. > >> > >> The LVDS interface has its own separate device node, so if you want to > >> be able to reset that, you need to add reset properties to the LVDS > >> node instead. > >> > >> Note that I haven't reposted a new version of "[PATCH v2] dt-bindings: > >> drm: rcar-du: Document optional reset properties"[1] yet, after the > >> split off of the LVDS interface into its own device node. Laurent wanted > >> to wait until the driver gained DU reset support. > >> However, the above differs from my proposal, as it also adds "du.1", > >> pointing to the same (shared) reset. > >> With a fresh look (2 years later ;-), that actually makes sense, so > >> perhaps I should change my proposal and repost? We do have shared > >> resets in other places (e.g. USB). > >> Laurent, what do you think? > > > > For Gen3 reset is handled at the group level, so I think specifying one > > entry per group is enough. If other SoCs require per-channel reset > > (which would surprise me as it would then imply a big redesign of the DU > > IP core, which may lead to a separate driver) we can always extend the > > bindings accordingly. > > > >> [1] https://lore.kernel.org/linux-renesas-soc/1488817556-21410-1-git-send-email-geert+renesas@xxxxxxxxx/ > > Sorry, I'm a little unclear on what the suggested way forwards is here. > > Is it to add a reset for du.0 but not du.1 ? Correct. -- Regards, Laurent Pinchart
