RE: [PATCH] PCI: exynos: Adapt to clk_bulk_* APIs

[Shradha Todi]

> -----Original Message-----
> From: Alim Akhtar [mailto:alim.akhtar@xxxxxxxxxxx]
> Sent: 09 November 2023 23:18
> To: 'Shradha Todi' <shradha.t@xxxxxxxxxxx>; jingoohan1@xxxxxxxxx;
> lpieralisi@xxxxxxxxxx; kw@xxxxxxxxx; robh@xxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; krzysztof.kozlowski@xxxxxxxxxx
> Cc: linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> samsung-soc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> pankaj.dubey@xxxxxxxxxxx
> Subject: RE: [PATCH] PCI: exynos: Adapt to clk_bulk_* APIs
> 
> Hi Shradha
> 
> > -----Original Message-----
> > From: Shradha Todi <shradha.t@xxxxxxxxxxx>
> > Sent: Monday, October 9, 2023 11:52 AM
> > To: jingoohan1@xxxxxxxxx; lpieralisi@xxxxxxxxxx; kw@xxxxxxxxx;
> > robh@xxxxxxxxxx; bhelgaas@xxxxxxxxxx; krzysztof.kozlowski@xxxxxxxxxx;
> > alim.akhtar@xxxxxxxxxxx
> > Cc: linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > linux- samsung-soc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > pankaj.dubey@xxxxxxxxxxx; Shradha Todi <shradha.t@xxxxxxxxxxx>
> > Subject: [PATCH] PCI: exynos: Adapt to clk_bulk_* APIs
> >
> > There is no need to hardcode the clock info in the driver as driver
> > can rely on the devicetree to supply the clocks required for the
> > functioning of the peripheral. Get rid of the static clock info and
> > obtain the platform supplied clocks. The total number of clocks
> > supplied is obtained using the
> > devm_clk_bulk_get_all() API and used for the rest of the clk_bulk_* APIs.
> >
> > Signed-off-by: Shradha Todi <shradha.t@xxxxxxxxxxx>
> > ---
> >  drivers/pci/controller/dwc/pci-exynos.c | 46
> > ++++++-------------------
> >  1 file changed, 11 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-exynos.c
> > b/drivers/pci/controller/dwc/pci-exynos.c
> > index 9e42cfcd99cc..023cf41fccd7 100644
> > --- a/drivers/pci/controller/dwc/pci-exynos.c
> > +++ b/drivers/pci/controller/dwc/pci-exynos.c
> > @@ -54,8 +54,8 @@
> >  struct exynos_pcie {
> >  	struct dw_pcie			pci;
> >  	void __iomem			*elbi_base;
> > -	struct clk			*clk;
> > -	struct clk			*bus_clk;
> > +	struct clk_bulk_data		*clks;
> > +	int				clk_cnt;
> >  	struct phy			*phy;
> >  	struct regulator_bulk_data	supplies[2];
> >  };
> > @@ -65,30 +65,18 @@ static int exynos_pcie_init_clk_resources(struct
> > exynos_pcie *ep)
> >  	struct device *dev = ep->pci.dev;
> >  	int ret;
> >
> > -	ret = clk_prepare_enable(ep->clk);
> > -	if (ret) {
> > -		dev_err(dev, "cannot enable pcie rc clock");
> > +	ret = devm_clk_bulk_get_all(dev, &ep->clks);
> > +	if (ret < 0)
> You can checking only for -ve value, what if  devm_clk_bulk_get_all() return
> 0?
> 

Thanks for the review!
Return value of 0 means there were no clocks to get but it does not indicate failure. It can mean
that the device does not need any clock handling in the driver. " clk_bulk_prepare_enable" takes
care of num_clks being 0 and returns success anyway. I have seen other drivers handling in a similar way.

> >  		return ret;
> > -	}
> >
> > -	ret = clk_prepare_enable(ep->bus_clk);
> > -	if (ret) {
> > -		dev_err(dev, "cannot enable pcie bus clock");
> > -		goto err_bus_clk;
> > -	}
> > +	ep->clk_cnt = ret;
> >
> > -	return 0;
> > -
> > -err_bus_clk:
> > -	clk_disable_unprepare(ep->clk);
> > -
> > -	return ret;
> > +	return clk_bulk_prepare_enable(ep->clk_cnt, ep->clks);
> >  }
> >
> >  static void exynos_pcie_deinit_clk_resources(struct exynos_pcie *ep)  {
> > -	clk_disable_unprepare(ep->bus_clk);
> > -	clk_disable_unprepare(ep->clk);
> > +	clk_bulk_disable_unprepare(ep->clk_cnt, ep->clks);
> >  }
> >
> >  static void exynos_pcie_writel(void __iomem *base, u32 val, u32 reg)
> > @@ -
> > 332,17 +320,9 @@ static int exynos_pcie_probe(struct platform_device
> > *pdev)
> >  	if (IS_ERR(ep->elbi_base))
> >  		return PTR_ERR(ep->elbi_base);
> >
> > -	ep->clk = devm_clk_get(dev, "pcie");
> > -	if (IS_ERR(ep->clk)) {
> > -		dev_err(dev, "Failed to get pcie rc clock\n");
> > -		return PTR_ERR(ep->clk);
> > -	}
> > -
> > -	ep->bus_clk = devm_clk_get(dev, "pcie_bus");
> > -	if (IS_ERR(ep->bus_clk)) {
> > -		dev_err(dev, "Failed to get pcie bus clock\n");
> > -		return PTR_ERR(ep->bus_clk);
> > -	}
> > +	ret = exynos_pcie_init_clk_resources(ep);
> > +	if (ret < 0)
> > +		return ret;
> >
> >  	ep->supplies[0].supply = "vdd18";
> >  	ep->supplies[1].supply = "vdd10";
> > @@ -351,10 +331,6 @@ static int exynos_pcie_probe(struct
> > platform_device
> > *pdev)
> >  	if (ret)
> >  		return ret;
> >
> > -	ret = exynos_pcie_init_clk_resources(ep);
> > -	if (ret)
> > -		return ret;
> > -
> >  	ret = regulator_bulk_enable(ARRAY_SIZE(ep->supplies), ep-
> > >supplies);
> >  	if (ret)
> >  		return ret;
> > @@ -369,8 +345,8 @@ static int exynos_pcie_probe(struct
> > platform_device
> > *pdev)
> >
> >  fail_probe:
> >  	phy_exit(ep->phy);
> > -	exynos_pcie_deinit_clk_resources(ep);
> >  	regulator_bulk_disable(ARRAY_SIZE(ep->supplies), ep->supplies);
> > +	exynos_pcie_deinit_clk_resources(ep);
> >
> >  	return ret;
> >  }
> > --
> > 2.17.1
>