Messages in this thread | | | Subject | Re: [PATCH v1 1/2] clk: intel: Add CGU clock driver for a new SoC | From | "Tanwar, Rahul" <> | Date | Wed, 4 Sep 2019 16:03:59 +0800 |
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Hi Martin,
On 4/9/2019 2:53 AM, Martin Blumenstingl wrote: >> My understanding is that if we do not use syscon, then there is no >> point in using regmap because this driver uses simple 32 bit register >> access. Can directly read/write registers using readl() & writel(). >> >> Would you agree ? > if there was only the LGM SoC then I would say: drop regmap > > however, last year a driver for the GRX350/GRX550 SoCs was proposed: [0] > this was never updated but it seems to use the same "framework" as the > LGM driver > with this in mind I am for keeping regmap support because. > I think it will be easier to add support for old SoCs like > GRX350/GRX550 (but also VRX200), because the PLL sub-driver (I am > assuming that it is similar on all SoCs) or some other helpers can be > re-used across various SoCs instead of "duplicating" code (where one > variant would use regmap and the other readl/writel).
Earlier, we had discussed about it in our team. There are no plans to
upstream mips based platform code, past up-streaming efforts for mips
platforms were also dropped. GRX350/GRX550/VRX200 are all mips
based platforms. Plan is to upstream only x86 based platforms. In-fact,
i had removed GRX & other older SoCs support from this driver before
sending for review. So we can consider only x86 based LGM family of
SoCs for this driver & all of them will be reusing same IP.
> [...] >>> + select OF_EARLY_FLATTREE >>> there's not a single other "select OF_EARLY_FLATTREE" in driver/clk >>> I'm not saying this is wrong but it makes me curious why you need this >> >> We need OF_EARLY_FLATTREE for LGM. But adding a new x86 >> platform for LGM is discouraged because that would lead to too >> many platforms. Only differentiating factor for LGM is CPU model >> ID but it can differentiate only at run time. So i had no option >> other then enabling it with some LGM specific core system module >> driver and CGU seemed perfect for this purpose. > so when my x86 kernel maintainer enables CONFIG_INTEL_LGM_CGU_CLK then > OF_EARLY_FLATTREE is enabled as well. > does this hurt any existing x86 platform? if not: why can't we enable > it for x86 unconditionally?
IMHO, it will not hurt any other existing x86 platform but enabling it for
x86 unconditionally also doesn't sound like a good idea. I now get your
point that enabling OF_EARLY_FLATTREE here is a bit odd. I will remove
it in next patch.
Regards,
Rahul
> I went through meson & qcom regmap clock code. Agree, it can be > reused for mux, divider and gate. But as mentioned above, i am now > considering to move away from using regmap. > thank you for evaluating them. let's continue the discussion above > whether regmap should be used - after that we decide (if needed) which > regmap implementation to use > > > Martin > > > [0] https://patchwork.kernel.org/patch/10554401/
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