linux-kernel - Re: [PATCH] PCI: dwc: dra7xx: Print link state to console for debug

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Date:   Mon, 16 Oct 2017 23:35:28 -0700
From:   Joe Perches <joe@...ches.com>
To:     Faiz Abbas <faiz_abbas@...com>, kishon@...com
Cc:     bhelgaas@...gle.com, linux-omap@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: dwc: dra7xx: Print link state to console for debug

On Tue, 2017-10-17 at 11:13 +0530, Faiz Abbas wrote:
> Enable support for printing the LTSSM link state for debugging PCI
> when link is down.
[]
> diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
> index 34427a6..7b150b0 100644
> --- a/drivers/pci/dwc/pci-dra7xx.c
> +++ b/drivers/pci/dwc/pci-dra7xx.c
> @@ -98,6 +98,18 @@ struct dra7xx_pcie_of_data {
>  
>  #define to_dra7xx_pcie(x)	dev_get_drvdata((x)->dev)
>  
> +static char state[][20] = {
> +	"DETECT_QUIET", "DETECT_ACT", "POLL_ACTIVE", "POLL_COMPLIANCE",
> +	"POLL_CONFIG", "PRE_DETECT_QUIET", "DETECT_WAIT", "CFG_LINKWD_START",
> +	"CFG_LINKWD_ACEPT", "CFG_LANENUM_WAIT", "CFG_LANENUM_ACEPT",
> +	"CFG_COMPLETE", "CFG_IDLE", "RCVRY_LOCK", "RCVRY_SPEED",
> +	"RCVRY_RCVRCFG", "RCVRY_IDLE", "L0", "L0S", "L123_SEND_EIDLE",
> +	"L1_IDLE", "L2_IDLE", "L2_WAKE", "DISABLED_ENTRY", "DISABLED_IDLE",
> +	"DISABLED", "LPBK_ENTRY", "LPBK_ACTIVE", "LPBK_EXIT",
> +	"LPBK_EXIT_TIMEOUT", "HOT_RESET_ENTRY", "HOT_RESET", "RCVRY_EQ0",
> +	"RCVRY_EQ1", "RCVRY_EQ2", "RCVRY_EQ3"

what's wrong with using the far more typical

static const char *link_state[] = {
	"DETECT_QUIET",
	...
};

> +};
> +
>  static inline u32 dra7xx_pcie_readl(struct dra7xx_pcie *pcie, u32 offset)
>  {
>  	return readl(pcie->base + offset);
> @@ -118,6 +130,15 @@ static int dra7xx_pcie_link_up(struct dw_pcie *pci)
>  {
>  	struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pci);
>  	u32 reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_PHY_CS);
> +	u32 cmd_reg;
> +	u32 ltssm_state;
> +
> +	if (!(reg & LINK_UP)) {
> +		cmd_reg = dra7xx_pcie_readl(dra7xx,
> +					    PCIECTRL_DRA7XX_CONF_DEVICE_CMD);
> +		ltssm_state = (cmd_reg & GENMASK(7, 2)) >> 2;
> +		dev_err(pci->dev, "Link state:%s\n", state[ltssm_state]);

and why is this a dev_err and not dev_info?
and if it's really for debugging, why not dev_dbg?

> +	}
>  
>  	return !!(reg & LINK_UP);
>  }