Hi Simon, Shimoda-san, On Mon, Mar 20, 2017 at 9:28 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote: > On Thu, Mar 16, 2017 at 03:07:22PM +0100, Geert Uytterhoeven wrote: >> This patch series describes the reset control topology for on-SoC devices >> connected to the Renesas Clock Pulse Generator / Module Standby and >> Software Reset module on the R-Car H3 and M3-W, RZ/G1M, and RZ/G1E SoCs. >> >> Resets usually match the corresponding module clocks. Exceptions are: >> - The Display Unit has only 2 resets, one per channel pair, cfr. >> "[PATCH v2] dt-bindings: drm: rcar-du: Document optional reset >> properties" (http://www.spinics.net/lists/dri-devel/msg134637.html), >> - The audio module has resets for the Serial Sound Interfaces only. >> Adding resets and reset-names properties depends on a DT binding >> update for renesas,rsnd (note: the DT binding documentation in >> Documentation/devicetree/bindings/sound/renesas,rsnd.txt doesn't >> even document clocks and clock-names?). >> Upon request from Laurent for the DU, and upon a DT bindings update >> for rcar_sound, the addition of resets (and reset-names) properties for >> these complex modules is postponed. >> >> Note that this patch series contains hardware description only. >> Actual reset policy is to be defined and implemented separately. >> Also, this is an optional feature, to be enabled explicitly using >> CONFIG_RESET_CONTROLLER=y. When enabled, an on-SoC device can be reset >> easily using device_reset(), or by using the reset_control_*() API when >> more fine-grained control is desired. >> >> Possible use cases are (not exhaustive): >> - Reset a device before use, to make sure it's in a predefined state, and >> doesn't depend on earlier configuration by e.g. the boot loader, >> - Reset a device after detecting an anomaly, >> - Reset a device to verify suspend/resume is handled correctly by the >> driver in case the device would be part of a power domain on a >> different/future SoC. >> >> Dependencies and impact: >> - The corresponding driver changes to the CGP/MSSR driver are already >> present in v4.11-rc1. >> - These patches have no impact as long as CONFIG_RESET_CONTROLLER=n. >> However, if CONFIG_RESET_CONTROLLER=y and resets properties are >> prsesent in DTS, the EHCI and OHCI drivers already deassert reset as >> part of their initialization sequences, and put the devices back >> into reset state in case initialization failed, or on unbind. >> I'm not aware of other relevant drivers already using reset control. > > It appears that for arm64 defconfig CONFIG_RESET_CONTROLLER=y is true so > by default there will be a behavioural change on arm64. I'd like to > understand if it is a desirable (or at least not undesirable) change. V1 of this patch series has been part of renesas-drivers since renesas-drivers-2017-01-24-v4.10-rc5, so I'd hope any negative impact would have been discovered by now. Shimoda-san: Have you noticed any oddities w.r.t. USB? Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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
