Re: [PATCH V3 02/12] PCI: tegra: Move REFCLK pad settings out of phy_power_on()

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On Mon, Oct 30, 2017 at 07:27:13PM +0530, Manikanta Maddireddy wrote:
> In Tegra186 PHY programming is done by BPMP-FW, so PHY calls are skipped

It is time you defined what FW does and what the kernel does and stick
to that SW initialization sequence for all Tegra PCI host bridges from
now onwards. Those tegra_pcie_soc structures in the driver will end up
with a gazillion hardcoded parameters if you do not take a stance from
that perspective and I do not like that - at all.

You may want to use DT bindings to describe the FW<->OS handover - or
just enforce firmware guidelines for Tegra systems - something has to be
done.

This patch makes sense stand-alone but I wanted to get the message
across.

Thanks,
Lorenzo

> in driver. REFCLK pad settings are independent of PHY and should be
> programmed by driver. So move REFCLK pad settings out of phy_power_on().
> These pad settings improve REFCLK peak to peak amplitude.
> 
> Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
> ---
> V3:
> * Corrected commit log
> V2:
> * no change in this patch
> 
>  drivers/pci/host/pci-tegra.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
> index b41c60c7414c..068510b40c1a 100644
> --- a/drivers/pci/host/pci-tegra.c
> +++ b/drivers/pci/host/pci-tegra.c
> @@ -910,7 +910,6 @@ static int tegra_pcie_port_phy_power_off(struct tegra_pcie_port *port)
>  static int tegra_pcie_phy_power_on(struct tegra_pcie *pcie)
>  {
>  	struct device *dev = pcie->dev;
> -	const struct tegra_pcie_soc *soc = pcie->soc;
>  	struct tegra_pcie_port *port;
>  	int err;
>  
> @@ -936,12 +935,6 @@ static int tegra_pcie_phy_power_on(struct tegra_pcie *pcie)
>  		}
>  	}
>  
> -	/* Configure the reference clock driver */
> -	pads_writel(pcie, soc->pads_refclk_cfg0, PADS_REFCLK_CFG0);
> -
> -	if (soc->num_ports > 2)
> -		pads_writel(pcie, soc->pads_refclk_cfg1, PADS_REFCLK_CFG1);
> -
>  	return 0;
>  }
>  
> @@ -2049,6 +2042,17 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
>  	return 0;
>  }
>  
> +static void tegra_pcie_apply_pad_settings(struct tegra_pcie *pcie)
> +{
> +	const struct tegra_pcie_soc *soc = pcie->soc;
> +
> +	/* Configure the reference clock driver */
> +	pads_writel(pcie, soc->pads_refclk_cfg0, PADS_REFCLK_CFG0);
> +
> +	if (soc->num_ports > 2)
> +		pads_writel(pcie, soc->pads_refclk_cfg1, PADS_REFCLK_CFG1);
> +}
> +
>  /*
>   * FIXME: If there are no PCIe cards attached, then calling this function
>   * can result in the increase of the bootup time as there are big timeout
> @@ -2107,6 +2111,8 @@ static void tegra_pcie_enable_ports(struct tegra_pcie *pcie)
>  	struct device *dev = pcie->dev;
>  	struct tegra_pcie_port *port, *tmp;
>  
> +	tegra_pcie_apply_pad_settings(pcie);
> +
>  	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
>  		dev_info(dev, "probing port %u, using %u lanes\n",
>  			 port->index, port->lanes);
> -- 
> 2.1.4
> 
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