linux-kernel - Re: [PATCHv2 1/2] clk: rockchip: rk3588: make gate linked clocks ignore unused

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Message-ID: <0ba154fe-5104-845c-a348-cebd4ee31716@rock-chips.com>
Date:   Fri, 28 Jul 2023 10:52:48 +0800
From:   zhangqing <zhangqing@...k-chips.com>
To:     Jagan Teki <jagan@...eble.ai>,
        Sebastian Reichel <sebastian.reichel@...labora.com>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        linux-rockchip@...ts.infradead.org,
        Peter Geis <pgwipeout@...il.com>,
        Finley Xiao <finley.xiao@...k-chips.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kernel@...labora.com,
        Vincent Legoll <vincent.legoll@...il.com>
Subject: Re: [PATCHv2 1/2] clk: rockchip: rk3588: make gate linked clocks
 ignore unused


在 2023/7/14 13:33, Jagan Teki 写道:
> Hi Sebastian,
>
> On Fri, 14 Jul 2023 at 01:08, Sebastian Reichel
> <sebastian.reichel@...labora.com> wrote:
>> Hello Jagan,
>>
>> On Thu, Jul 13, 2023 at 08:25:03PM +0530, Jagan Teki wrote:
>>> On Tue, 4 Apr 2023 at 01:03, Sebastian Reichel
>>> <sebastian.reichel@...labora.com> wrote:
>>> [...]
>>>> + * Recent Rockchip SoCs have a new hardware block called Native Interface
>>>> + * Unit (NIU), which gates clocks to devices behind them. These effectively
>>>> + * need two parent clocks.
>>>> + *
>>>> + * Downstream enables the linked clock via runtime PM whenever the gate is
>>>> + * enabled. This implementation uses separate clock nodes for each of the
>>>> + * linked gate clocks, which leaks parts of the clock tree into DT.
>>>> + *
>>>> + * The GATE_LINK macro instead takes the second parent via 'linkname', but
>>>> + * ignores the information. Once the clock framework is ready to handle it, the
>>>> + * information should be passed on here. But since these clocks are required to
>>>> + * access multiple relevant IP blocks, such as PCIe or USB, we mark all linked
>>>> + * clocks critical until a better solution is available. This will waste some
>>>> + * power, but avoids leaking implementation details into DT or hanging the
>>>> + * system.
>>>>    */
>>> Does it mean the clk-link topology in the downstream kernel can be
>>> reused the same as normal clock notation?
>> Yes.
>>
>>> For example, I'm trying to add HCLK_VO1 directly to VO1 syscon instead
>>> of routing to pclk_vo1_grf(done downstream)
>>>        vo1_grf: syscon@...a8000 {
>>>                 compatible = "rockchip,rk3588-vo-grf", "syscon";
>>>                 reg = <0x0 0xfd5a8000 0x0 0x100>;
>>>               clocks = <&cru HCLK_VO1>;
>> You need PCLK_VO1 (which is currently not exposed; I somehow missed
>> it).
Maybe this submission is helpful

The true GATE_LINK callback is implemented.

https://patchwork.kernel.org/project/linux-clk/patch/20230728020810.29732-4-zhangqing@rock-chips.com/

  vo1_grf: syscon@...a8000 {
                compatible = "rockchip,rk3588-vo-grf", "syscon";
                reg = <0x0 0xfd5a8000 0x0 0x100>;
              clocks = <&cru PCLK_VO1GRF>;

When enable pclk_vo1grf,will enable pclk_vo1_root and hclk_vo1.

>>>        };
>>>
>>> This seems breaking syscon for vo1_grf and observed a bus error
>>> while accessing regmap.
>> I investigated the issue you are seeing some weeks ago when my
>> co-workers started to work on HDMI RX and TX. You are probably
>> just missing this patch:
>>
>> https://gitlab.collabora.com/hardware-enablement/rockchip-3588/linux/-/commit/ecc6415344957fa88356cec10f8b75a9da603a7b
> In fact, I tried this solution as well, by connecting the PCLK_VO1GRF.
>
>          vo1_grf: syscon@...a8000 {
>                  compatible = "rockchip,rk3588-vo-grf", "syscon";
>                  reg = <0x0 0xfd5a8000 0x0 0x100>;
>                  clocks = <&cru PCLK_VO1GRF>;
>          };
>
> But the result seems the same, accessing vo1_grf triggers an abort [1]
>
> [1] https://gist.github.com/openedev/e241da8180341ffbf4dc6a26de7efa31
>
> Thanks,
> Jagan.

-- 
张晴
瑞芯微电子股份有限公司
Rockchip Electronics Co.,Ltd
地址：福建省福州市铜盘路软件大道89号软件园A区21号楼
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E-mail:elaine.zhang@...k-chips.com
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