RE: [PATCH v2 4/6] PCI: dwc: rcar-gen4: Add a new function pointer for other SoC support

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Hi Bjorn,

> From: Bjorn Helgaas, Sent: Wednesday, March 27, 2024 5:21 AM
> 
> Include the function pointer name in the subject so it's a little more
> specific.

I got it. I'll change the subject.

> On Tue, Mar 26, 2024 at 11:45:38AM +0900, Yoshihiro Shimoda wrote:
> > This driver can reuse other R-Car Gen4 SoC support. However, some
> > initializing settings differs between r8a779f0 and others. So, add
> > a new function pointer start_link_enable() to support other R-Car
> > Gen4 SoC in the future. No behavior changes.
> 
> Make it clear here what the new SoC is.  I think it's r8a779f0, but
> you have to read the patch and look for the new .compatible string to
> figure that out.

I got it. The new SoC is r8a779g0. So, I should add such description here.

> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > ---
> >  drivers/pci/controller/dwc/pcie-rcar-gen4.c | 57 +++++++++++++++++++--
> >  1 file changed, 52 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > index 0be760ed420b..a37613dd9ff4 100644
> > --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> > @@ -53,9 +53,16 @@ struct rcar_gen4_pcie {
> >  	void __iomem *base;
> >  	struct platform_device *pdev;
> >  	enum dw_pcie_device_mode mode;
> > +
> > +	int (*start_link_enable)(struct rcar_gen4_pcie *rcar);
> >  };
> >  #define to_rcar_gen4_pcie(_dw)	container_of(_dw, struct rcar_gen4_pcie, dw)
> >
> > +struct rcar_gen4_pcie_platdata {
> > +	enum dw_pcie_device_mode mode;
> > +	int (*start_link_enable)(struct rcar_gen4_pcie *rcar);
> 
> I think it's confusing to repeat "mode" and "start_link_enable" in
> both rcar_gen4_pcie and rcar_gen4_pcie_platdata.  I know several other
> drivers use this pattern, but I think it is simpler overall to just
> save the pointer directly, e.g.,
> 
>   imx6_pcie_probe
>     imx6_pcie->drvdata = of_device_get_match_data(dev);
> 
>   ls_pcie_probe
>     pcie->drvdata = of_device_get_match_data(dev);
> 
>   tegra_pcie_dw_probe
>     data = of_device_get_match_data(dev);
>     pcie->of_data = (struct tegra_pcie_dw_of_data *)data;
> 
> So I think the best thing would be to add struct
> rcar_gen4_pcie_platdata, *move* rcar_gen4_pcie.mode there, and save a
> pointer to the rcar_gen4_pcie_platdata in struct rcar_gen4_pcie.

I got it. I'll modify the patch.

> That could be its own separate patch, which is nice on its own because
> it gets rid of the (void *) casts in rcar_gen4_pcie_of_match[].
> 
> Then add .start_link_enable() (or .ltssm_enable(), see below) and the
> r8a779f0 bits in another patch.

I got it. I'll make such a patch at first.

> > +};
> > +
> >  /* Common */
> >  static void rcar_gen4_pcie_ltssm_enable(struct rcar_gen4_pcie *rcar,
> >  					bool enable)
> > @@ -123,9 +130,13 @@ static int rcar_gen4_pcie_speed_change(struct dw_pcie *dw)
> >  static int rcar_gen4_pcie_start_link(struct dw_pcie *dw)
> >  {
> >  	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> > -	int i, changes;
> > +	int i, changes, ret;
> >
> > -	rcar_gen4_pcie_ltssm_enable(rcar, true);
> > +	if (rcar->start_link_enable) {
> > +		ret = rcar->start_link_enable(rcar);
> 
> This looks basically like what qcom does:
> 
>   qcom_pcie_start_link
>     if (pcie->cfg->ops->ltssm_enable)
>       pcie->cfg->ops->ltssm_enable(pcie)
> 
> Can you copy that and use the same name for the pointer and function
> name (.ltssm_enable, .*_ltssm_enable())?

Yes, I can. I'll rename the pointer and function.

> > +		if (ret)
> > +			return ret;
> > +	}
> >
> >  	/*
> >  	 * Require direct speed change with retrying here if the link_gen is
> > @@ -437,7 +448,10 @@ static void rcar_gen4_remove_dw_pcie_ep(struct rcar_gen4_pcie *rcar)
> >  /* Common */
> >  static int rcar_gen4_add_dw_pcie(struct rcar_gen4_pcie *rcar)
> >  {
> > -	rcar->mode = (uintptr_t)of_device_get_match_data(&rcar->pdev->dev);
> > +	const struct rcar_gen4_pcie_platdata *pd = of_device_get_match_data(&rcar->pdev->dev);
> > +
> > +	rcar->mode = pd->mode;
> > +	rcar->start_link_enable = pd->start_link_enable;
> >
> >  	switch (rcar->mode) {
> >  	case DW_PCIE_RC_TYPE:
> > @@ -500,14 +514,47 @@ static void rcar_gen4_pcie_remove(struct platform_device *pdev)
> >  	rcar_gen4_pcie_unprepare(rcar);
> >  }
> >
> > +static int r8a779f0_pcie_start_link_enable(struct rcar_gen4_pcie *rcar)
> > +{
> > +	rcar_gen4_pcie_ltssm_enable(rcar, true);
> 
> Previously we called rcar_gen4_pcie_ltssm_enable() for
> "renesas,rcar-gen4-pcie" and "renesas,rcar-gen4-pcie-ep".  But after
> this patch, it looks like we only call it for "renesas,r8a779f0-pcie"
> and "renesas,r8a779f0-pcie-ep"?

Yes.

Best regards,
Yoshihiro Shimoda

> > +
> > +	return 0;
> > +}
> > +
> > +static struct rcar_gen4_pcie_platdata platdata_r8a779f0_pcie = {
> > +	.mode = DW_PCIE_RC_TYPE,
> > +	.start_link_enable = r8a779f0_pcie_start_link_enable,
> > +};
> > +
> > +static struct rcar_gen4_pcie_platdata platdata_r8a779f0_pcie_ep = {
> > +	.mode = DW_PCIE_EP_TYPE,
> > +	.start_link_enable = r8a779f0_pcie_start_link_enable,
> > +};
> > +
> > +static struct rcar_gen4_pcie_platdata platdata_rcar_gen4_pcie = {
> > +	.mode = DW_PCIE_RC_TYPE,
> > +};
> > +
> > +static struct rcar_gen4_pcie_platdata platdata_rcar_gen4_pcie_ep = {
> > +	.mode = DW_PCIE_EP_TYPE,
> > +};
> > +
> >  static const struct of_device_id rcar_gen4_pcie_of_match[] = {
> > +	{
> > +		.compatible = "renesas,r8a779f0-pcie",
> > +		.data = &platdata_r8a779f0_pcie,
> > +	},
> > +	{
> > +		.compatible = "renesas,r8a779f0-pcie-ep",
> > +		.data = &platdata_r8a779f0_pcie_ep,
> > +	},
> >  	{
> >  		.compatible = "renesas,rcar-gen4-pcie",
> > -		.data = (void *)DW_PCIE_RC_TYPE,
> > +		.data = &platdata_rcar_gen4_pcie,
> >  	},
> >  	{
> >  		.compatible = "renesas,rcar-gen4-pcie-ep",
> > -		.data = (void *)DW_PCIE_EP_TYPE,
> > +		.data = &platdata_rcar_gen4_pcie_ep,
> >  	},
> >  	{},
> >  };
> > --
> > 2.25.1
> >





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