linux-kernel - Re: [PATCH 3/6] soc: qcom: ocmem: make iface clock optional

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Message-ID: <f9cfa346-42f8-8061-3517-947440c6f860@linaro.org>
Date:   Wed, 10 May 2023 00:32:50 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Luca Weiss <luca@...tu.xyz>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Clark <robdclark@...il.com>,
        Brian Masney <masneyb@...tation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 3/6] soc: qcom: ocmem: make iface clock optional



On 9.05.2023 23:41, Luca Weiss wrote:
> On Dienstag, 9. Mai 2023 19:08:50 CEST Dmitry Baryshkov wrote:
>> On Tue, 9 May 2023 at 19:47, Luca Weiss <luca@...tu.xyz> wrote:
>>> On Montag, 8. Mai 2023 13:34:23 CEST Dmitry Baryshkov wrote:
>>>> On 07/05/2023 12:12, Luca Weiss wrote:
>>>>> Some platforms such as msm8226 do not have an iface clk. Since
>>>>> clk_bulk
>>>>> APIs don't offer to a way to treat some clocks as optional simply add
>>>>> core_clk and iface_clk members to our drvdata.
>>>>
>>>> What about using devm_clk_bulk_get_optional()? I think it would be
>>>> simpler this way.
>>>
>>> Using that function both clocks would be optional which may or may not be
>>> a
>>> bad idea. Not sure how much binding yaml and/or driver should try and
>>> catch
>>> bad usages of the driver.
>>
>> The generic rule is that we should not validate the DT unless required
>> (e.g. because of the possibility of legacy DT which used other
>> bindings or contained less information).
> 
> Got it.
> 
> But since in this driver we use one of the clocks for setting clock rate I'd
> keep using the two separate struct clk as I've done in this patch if you don't
> mind too much.
I'd also advocate for 2x struct clk, using bulk here is like trying to
spread butter with a fork, it works, but has holes..

Konrad
> 
> Regards
> Luca
> 
>>
>>> But honestly the current usage of the bulk API seems a bit clunky, we have
>>> a static array of clocks that we use (not in struct ocmem for some
>>> reason) and then we refer to the core clock by index? Feels better to
>>> just have the two clock references in the device struct and then we're
>>> good.
>>>
>>> Let me know.
>>>
>>> Regards
>>> Luca
>>>
>>>>> Signed-off-by: Luca Weiss <luca@...tu.xyz>
>>>>> ---
>>>>>
>>>>>   drivers/soc/qcom/ocmem.c | 42
>>>>>   ++++++++++++++++++++++++------------------
>>>>>   1 file changed, 24 insertions(+), 18 deletions(-)
>>>>>
>>>>> diff --git a/drivers/soc/qcom/ocmem.c b/drivers/soc/qcom/ocmem.c
>>>>> index a11a955a1327..6235065d3bc9 100644
>>>>> --- a/drivers/soc/qcom/ocmem.c
>>>>> +++ b/drivers/soc/qcom/ocmem.c
>>>>> @@ -54,6 +54,8 @@ struct ocmem {
>>>>>
>>>>>     const struct ocmem_config *config;
>>>>>     struct resource *memory;
>>>>>     void __iomem *mmio;
>>>>>
>>>>> +   struct clk *core_clk;
>>>>> +   struct clk *iface_clk;
>>>>>
>>>>>     unsigned int num_ports;
>>>>>     unsigned int num_macros;
>>>>>     bool interleaved;
>>>>>
>>>>> @@ -91,16 +93,6 @@ struct ocmem {
>>>>>
>>>>>   #define OCMEM_PSGSC_CTL_MACRO2_MODE(val)  FIELD_PREP(0x00000700,
>>>
>>> (val))
>>>
>>>>>   #define OCMEM_PSGSC_CTL_MACRO3_MODE(val)  FIELD_PREP(0x00007000,
>>>
>>> (val))
>>>
>>>>> -#define OCMEM_CLK_CORE_IDX                 0
>>>>> -static struct clk_bulk_data ocmem_clks[] = {
>>>>> -   {
>>>>> -           .id = "core",
>>>>> -   },
>>>>> -   {
>>>>> -           .id = "iface",
>>>>> -   },
>>>>> -};
>>>>> -
>>>>>
>>>>>   static inline void ocmem_write(struct ocmem *ocmem, u32 reg, u32
>>>>>   data)
>>>>>   {
>>>>>   
>>>>>     writel(data, ocmem->mmio + reg);
>>>>>
>>>>> @@ -316,9 +308,15 @@ static int ocmem_dev_probe(struct platform_device
>>>>> *pdev)>
>>>>>
>>>>>     ocmem->dev = dev;
>>>>>     ocmem->config = device_get_match_data(dev);
>>>>>
>>>>> -   ret = devm_clk_bulk_get(dev, ARRAY_SIZE(ocmem_clks), ocmem_clks);
>>>>> -   if (ret)
>>>>> -           return dev_err_probe(dev, ret, "Unable to get clocks\n");
>>>>> +   ocmem->core_clk = devm_clk_get(dev, "core");
>>>>> +   if (IS_ERR(ocmem->core_clk))
>>>>> +           return dev_err_probe(dev, PTR_ERR(ocmem->core_clk),
>>>>> +                                "Unable to get core clock\n");
>>>>> +
>>>>> +   ocmem->iface_clk = devm_clk_get_optional(dev, "iface");
>>>>> +   if (IS_ERR(ocmem->iface_clk))
>>>>> +           return dev_err_probe(dev, PTR_ERR(ocmem->iface_clk),
>>>>> +                                "Unable to get iface clock\n");
>>>>>
>>>>>     ocmem->mmio = devm_platform_ioremap_resource_byname(pdev, "ctrl");
>>>>>     if (IS_ERR(ocmem->mmio))
>>>>>
>>>>> @@ -333,11 +331,15 @@ static int ocmem_dev_probe(struct
>>>>> platform_device
>>>>> *pdev)>
>>>>>
>>>>>     }
>>>>>     
>>>>>     /* The core clock is synchronous with graphics */
>>>>>
>>>>> -   WARN_ON(clk_set_rate(ocmem_clks[OCMEM_CLK_CORE_IDX].clk, 1000) <
>>>>> 0);
>>>>> +   WARN_ON(clk_set_rate(ocmem->core_clk, 1000) < 0);
>>>>> +
>>>>> +   ret = clk_prepare_enable(ocmem->core_clk);
>>>>> +   if (ret)
>>>>> +           return dev_err_probe(ocmem->dev, ret, "Failed to enable
>>>
>>> core clock\n");
>>>
>>>>> -   ret = clk_bulk_prepare_enable(ARRAY_SIZE(ocmem_clks), ocmem_clks);
>>>>> +   ret = clk_prepare_enable(ocmem->iface_clk);
>>>>>
>>>>>     if (ret)
>>>>>
>>>>> -           return dev_err_probe(ocmem->dev, ret, "Failed to enable
>>>
>>> clocks\n");
>>>
>>>>> +           return dev_err_probe(ocmem->dev, ret, "Failed to enable
>>>
>>> iface
>>>
>>>>> clock\n");
>>>>>
>>>>>     if (qcom_scm_restore_sec_cfg_available()) {
>>>>>     
>>>>>             dev_dbg(dev, "configuring scm\n");
>>>>>
>>>>> @@ -396,13 +398,17 @@ static int ocmem_dev_probe(struct
>>>>> platform_device
>>>>> *pdev)>
>>>>>
>>>>>     return 0;
>>>>>   
>>>>>   err_clk_disable:
>>>>> -   clk_bulk_disable_unprepare(ARRAY_SIZE(ocmem_clks), ocmem_clks);
>>>>> +   clk_disable_unprepare(ocmem->core_clk);
>>>>> +   clk_disable_unprepare(ocmem->iface_clk);
>>>>>
>>>>>     return ret;
>>>>>   
>>>>>   }
>>>>>   
>>>>>   static int ocmem_dev_remove(struct platform_device *pdev)
>>>>>   {
>>>>>
>>>>> -   clk_bulk_disable_unprepare(ARRAY_SIZE(ocmem_clks), ocmem_clks);
>>>>> +   struct ocmem *ocmem = platform_get_drvdata(pdev);
>>>>> +
>>>>> +   clk_disable_unprepare(ocmem->core_clk);
>>>>> +   clk_disable_unprepare(ocmem->iface_clk);
>>>>>
>>>>>     return 0;
>>>>>   
>>>>>   }
> 
> 
> 
>