On Thu, Mar 16, 2017 at 03:07:22PM +0100, Geert Uytterhoeven wrote: > Hi Simon, Magnus, Laurent, Morimoto-san, > > 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. > For testing, these patches are also available in the > topic/renesas-cpg-mssr-reset-dts-v2 branch of my renesas-drivers git > repository at > git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git > > This has been tested on the R-Car Gen3 Salvator-X (H3 and M3-W) and the > R-Car M2-W (using out-of-tree driver modifications) Koelsch development > boards, by inspecting device register contents before and after reset, > and by comparing them with their documented reset values. > > Changes compared to v1: > - Break out from "[PATCH 0/8] Renesas CPG/MSSR Reset Control Support" > (https://lkml.org/lkml/2017/1/20/336), > - Postpone adding resets and reset-names properties for complex > devices (du, rcar_sound), > - Rebase on top of renesas-devel-20170313-v4.11-rc2, > - Add reset properties to recently added device nodes. > > Thanks for applying! > > Geert Uytterhoeven (4): > arm64: dts: r8a7795: Add reset control properties > arm64: dts: r8a7796: Add reset control properties > ARM: dts: r8a7743: Add reset control properties > ARM: dts: r8a7745: Add reset control properties > > arch/arm/boot/dts/r8a7743.dtsi | 24 +++++++++ > arch/arm/boot/dts/r8a7745.dtsi | 24 +++++++++ > arch/arm64/boot/dts/renesas/r8a7795.dtsi | 93 ++++++++++++++++++++++++++++++++ > arch/arm64/boot/dts/renesas/r8a7796.dtsi | 46 ++++++++++++++++ > 4 files changed, 187 insertions(+) > > -- > 2.7.4 > > 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
