Messages in this thread |  | | Date | Sun, 29 Jan 2023 11:49:36 +0100 | Subject | Re: [PATCH] driver: bus: simple-pm-bus: Add Freescale i.MX8qm/qxp CSR compatible strings | From | Krzysztof Kozlowski <> |
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On 29/01/2023 09:13, Liu Ying wrote: > On Thu, 2023-01-26 at 13:45 +0100, Krzysztof Kozlowski wrote: >> On 26/01/2023 03:54, Liu Ying wrote: >>> On Wed, 2023-01-25 at 10:05 +0100, Geert Uytterhoeven wrote: >>>> Hi Liu, >>> >>> Hi Geert, >>> >>>> >>>> On Wed, Jan 25, 2023 at 9:31 AM Liu Ying <victor.liu@nxp.com> >>>> wrote: >>>>> Freescale i.MX8qm/qxp CSR module matches with what the simple >>>>> power >>>>> managed bus driver does, considering it needs an IPG clock to >>>>> be >>>>> enabled before accessing it's child devices, the child devices >>>>> need >>>>> to be populated by the CSR module and the child devices' power >>>>> management operations need to be propagated to their parent >>>>> devices. >>>>> Add the CSR module's compatible strings to >>>>> simple_pm_bus_of_match[] >>>>> table to support the CSR module. >>>>> >>>>> Suggested-by: Rob Herring <robh@kernel.org> >>>>> Suggested-by: Lee Jones <lee@kernel.org> >>>>> Signed-off-by: Liu Ying <victor.liu@nxp.com> >>>> >>>> Thanks for your patch! >>> >>> Thanks for your review! >>> >>>> >>>>> --- >>>>> The CSR module's dt-binding documentation can be found at >>>>> Documentation/devicetree/bindings/mfd/fsl,imx8qxp-csr.yaml. >>>>> >>>>> Suggested by Rob and Lee in this thread: >>>>> >>> >>> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fproject%2Flinux-arm-kernel%2Fpatch%2F20221017075702.4182846-1-victor.liu%40nxp.com%2F&data=05%7C01%7Cvictor.liu%40nxp.com%7C87515adc8fc3401f410808daff9b3279%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C638103339276325657%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=FFz5gSIPc6vyvb1IJ1Umu62WpzjNLIiQIi2sOA3RQGc%3D&reserved=0 >>>>> >>>>> drivers/bus/simple-pm-bus.c | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple- >>>>> pm- >>>>> bus.c >>>>> index 7afe1947e1c0..4a7575afe6c6 100644 >>>>> --- a/drivers/bus/simple-pm-bus.c >>>>> +++ b/drivers/bus/simple-pm-bus.c >>>>> @@ -120,6 +120,8 @@ static const struct of_device_id >>>>> simple_pm_bus_of_match[] = { >>>>> { .compatible = "simple-mfd", .data = ONLY_BUS }, >>>>> { .compatible = "isa", .data = ONLY_BUS }, >>>>> { .compatible = "arm,amba-bus", .data = ONLY_BUS }, >>>>> + { .compatible = "fsl,imx8qm-lvds-csr", }, >>>>> + { .compatible = "fsl,imx8qxp-mipi-lvds-csr", }, >>>> >>>> I did read the thread linked above, and I still think you should >>>> just >>>> add "simple-pm-bus" to the compatible value in DTS, so no driver >>>> change >>>> is needed, cfr. >>>> Documentation/devicetree/bindings/bus/renesas,bsc.yaml. >> >> I don't think we want to start putting specific compatibles here. We >> don't do it for simple-mfd, syscon and simple-bus, so neither should >> we >> do it here. >> >>> >>> This means that i.MX8qm/qxp CSR module dt-binding documentation >>> needs >>> to be changed. I'd like to know how Rob and Krzysztof think about >>> that. >> >> The fsl,imx8qxp-csr.yaml bindings are broken anyway... You have >> device >> specific bindings for non-simple device but use simple-mfd. You >> cannot. >> simple-mfd means it is simple and none of the resources are needed >> for >> children, but that binding contradicts it. >> >> Now you kind of try to extend it even more make it more and more >> broken. >> >> Rework the bindings keeping them backwards compatible. The >> combination >> with simple-mfd should be deprecated and you can add whatever is >> needed >> for a proper setup. > > I did try to rework the bindings and make the combination with simple- > mfd deprecated. However, it reminds me the problem that "simple-pm-bus" > and "syscon" can not be in compatible string at the same time, > otherwise, nodename should match '^syscon@[0-9a-f]+$' and '^bus@[0-9a- > f]+$' at the same time. I mentioned the problem in the same thread[1] > where Rob and Lee suggest to go with this patch. "syscon" is needed > since i.MX8qxp MIPI DSI/LVDS combo PHY node references the CSR module > through a phandle, so dropping/deprecating "syscon" is a no-go. > > Also, as Rob mentioned in [1] "if register space is all mixed together, > then it is the former and an MFD", I think the CSR module should fall > into the simple-mfd category.
You are now mixing MFD with simple-mfd. If you have clocks there or any other resources, it's not simple-mfd anymore.
> Take i.MX8qxp MIPI DSI/LVDS CSR module as > an example, child device pxl2dpi register offset is 0x40, while child > device ldb register offsets are 0x20 and 0xe0. > > Geert, Krzysztof, can you please consider to keep this patch as-is, > since it seems that there is no other option?
There are other options, why do you say there is no? Making it proper binding/driver for its children without abusing simple bindings. Simple bindings are for simple cases and this turns out not the simple case.
Best regards, Krzysztof
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