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

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Message-ID: <4094905.iIbC2pHGDl@z3ntu.xyz>
Date:   Tue, 09 May 2023 23:41:02 +0200
From:   Luca Weiss <luca@...tu.xyz>
To:     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>,
        Konrad Dybcio <konrad.dybcio@...aro.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 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.

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;
> > > >   
> > > >   }