Re: [PATCH v18 08/20] PCI: dwc: Add dw_pcie_link_set_max_link_width()

[Serge Semin <fancer.lancer@gmail.com>]

On Fri, Jul 21, 2023 at 04:44:40PM +0900, Yoshihiro Shimoda wrote:
> To improve code readability, add dw_pcie_link_set_max_link_width().

You completely ignored all my comments regarding this patch again.
It's getting to be annoying really.

Once again: "This patch is a preparation before adding the
Max-Link-width capability setup which would in its turn complete the
max-link-width setup procedure defined by Synopsys in the HW-manual.
Seeing there is a max-link-speed setup method defined in the DW PCIe
core driver it would be good to have a similar function for the link
width setup. That's why we need to define a dedicated function first
from already implemented but incomplete link-width setting up
code." This is what should have been described in the commit log.
If you were a side-reader of the patch could you guess that from your
commit log and the patch content? I bet you couldn't. That's why a
very thorough description is important.

> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 86 ++++++++++----------
>  1 file changed, 41 insertions(+), 45 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 2d0f816fa0ab..5cca34140d2a 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -728,6 +728,46 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
>  
>  }
>  
> +static void dw_pcie_link_set_max_link_width(struct dw_pcie *pci, u32 num_lanes)
> +{
> +	u32 lwsc, plc;
> +
> +	if (!num_lanes)
> +		return;
> +
> +	/* Set the number of lanes */
> +	plc = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);

> +	plc &= ~PORT_LINK_FAST_LINK_MODE;

Once again: this masking is unrelated to the link width setup.
Moreover it's completely redundant in here and in the original code.
See further for details.

> +	plc &= ~PORT_LINK_MODE_MASK;
> +
> +	/* Set link width speed control register */
> +	lwsc = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> +	lwsc &= ~PORT_LOGIC_LINK_WIDTH_MASK;
> +	switch (num_lanes) {
> +	case 1:
> +		plc |= PORT_LINK_MODE_1_LANES;
> +		lwsc |= PORT_LOGIC_LINK_WIDTH_1_LANES;
> +		break;
> +	case 2:
> +		plc |= PORT_LINK_MODE_2_LANES;
> +		lwsc |= PORT_LOGIC_LINK_WIDTH_2_LANES;
> +		break;
> +	case 4:
> +		plc |= PORT_LINK_MODE_4_LANES;
> +		lwsc |= PORT_LOGIC_LINK_WIDTH_4_LANES;
> +		break;
> +	case 8:
> +		plc |= PORT_LINK_MODE_8_LANES;
> +		lwsc |= PORT_LOGIC_LINK_WIDTH_8_LANES;
> +		break;
> +	default:
> +		dev_err(pci->dev, "num-lanes %u: invalid value\n", num_lanes);
> +		return;
> +	}
> +	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, plc);
> +	dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, lwsc);
> +}
> +
>  void dw_pcie_iatu_detect(struct dw_pcie *pci)
>  {
>  	int max_region, ob, ib;
> @@ -1009,49 +1049,5 @@ void dw_pcie_setup(struct dw_pcie *pci)
>  	val |= PORT_LINK_DLL_LINK_EN;
>  	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
>  
> -	if (!pci->num_lanes) {
> -		dev_dbg(pci->dev, "Using h/w default number of lanes\n");
> -		return;
> -	}
> -
> -	/* Set the number of lanes */

> -	val &= ~PORT_LINK_FAST_LINK_MODE;

My series contains the patch which drops this line:
https://patchwork.kernel.org/project/linux-pci/patch/20230611192005.25636-6-Sergey.Semin@baikalelectronics.ru/
So either pick my patch up and add it to your series or still pick it up
but with changing the authorship and adding me under the Suggested-by
tag with the email-address I am using to review your series. Bjorn,
what approach would you prefer? Perhaps alternative?

Note the patch I am talking about doesn't contain anything what
couldn't be merged in. The problem with my series is in completely
another dimension.

Bjorn

> -	val &= ~PORT_LINK_MODE_MASK;
> -	switch (pci->num_lanes) {
> -	case 1:
> -		val |= PORT_LINK_MODE_1_LANES;
> -		break;
> -	case 2:
> -		val |= PORT_LINK_MODE_2_LANES;
> -		break;
> -	case 4:
> -		val |= PORT_LINK_MODE_4_LANES;
> -		break;
> -	case 8:
> -		val |= PORT_LINK_MODE_8_LANES;
> -		break;
> -	default:
> -		dev_err(pci->dev, "num-lanes %u: invalid value\n", pci->num_lanes);
> -		return;
> -	}
> -	dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, val);
> -
> -	/* Set link width speed control register */
> -	val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> -	val &= ~PORT_LOGIC_LINK_WIDTH_MASK;
> -	switch (pci->num_lanes) {
> -	case 1:
> -		val |= PORT_LOGIC_LINK_WIDTH_1_LANES;
> -		break;
> -	case 2:
> -		val |= PORT_LOGIC_LINK_WIDTH_2_LANES;
> -		break;
> -	case 4:
> -		val |= PORT_LOGIC_LINK_WIDTH_4_LANES;
> -		break;
> -	case 8:
> -		val |= PORT_LOGIC_LINK_WIDTH_8_LANES;
> -		break;
> -	}
> -	dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> +	dw_pcie_link_set_max_link_width(pci, pci->num_lanes);
>  }
> -- 
> 2.25.1
>