Re: [PATCH v2] PCI: mediatek-gen3: Print LTSSM state when PCIe link down

From: Bjorn Helgaas <helgaas@kernel.org>
To: Jianjun Wang <jianjun.wang@mediatek.com>
Cc: "Ryder Lee" <ryder.lee@mediatek.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, jieyy.yang@mediatek.com,
	chuanjia.liu@mediatek.com, qizhong.cheng@mediatek.com,
	jian.yang@mediatek.com
Subject: Re: [PATCH v2] PCI: mediatek-gen3: Print LTSSM state when PCIe link down
Date: Wed, 15 Jun 2022 14:59:12 -0500	[thread overview]
Message-ID: <20220615195912.GA1024264@bhelgaas> (raw)
In-Reply-To: <20220329030715.7975-1-jianjun.wang@mediatek.com>

On Tue, Mar 29, 2022 at 11:07:15AM +0800, Jianjun Wang wrote:
> Print current LTSSM state when PCIe link down instead of the register
> value, make it easier to get the link status.
> 
> Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
> Changes in v2:
> Print both of the register value and the LTSSM state.

Applied to pci/ctrl/mediatek-gen3 for v5.20, thanks!

> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 41 ++++++++++++++++++++-
>  1 file changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> index 6745076a02b9..c24e03c198b7 100644
> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> @@ -153,6 +153,37 @@ struct mtk_gen3_pcie {
>  	DECLARE_BITMAP(msi_irq_in_use, PCIE_MSI_IRQS_NUM);
>  };
>  
> +/* LTSSM state in PCIE_LTSSM_STATUS_REG bit[28:24] */
> +static const char *const ltssm_str[] = {
> +	"detect.quiet",			/* 0x00 */
> +	"detect.active",		/* 0x01 */
> +	"polling.active",		/* 0x02 */
> +	"polling.compliance",		/* 0x03 */
> +	"polling.configuration",	/* 0x04 */
> +	"config.linkwidthstart",	/* 0x05 */
> +	"config.linkwidthaccept",	/* 0x06 */
> +	"config.lanenumwait",		/* 0x07 */
> +	"config.lanenumaccept",		/* 0x08 */
> +	"config.complete",		/* 0x09 */
> +	"config.idle",			/* 0x0A */
> +	"recovery.receiverlock",	/* 0x0B */
> +	"recovery.equalization",	/* 0x0C */
> +	"recovery.speed",		/* 0x0D */
> +	"recovery.receiverconfig",	/* 0x0E */
> +	"recovery.idle",		/* 0x0F */
> +	"L0",				/* 0x10 */
> +	"L0s",				/* 0x11 */
> +	"L1.entry",			/* 0x12 */
> +	"L1.idle",			/* 0x13 */
> +	"L2.idle",			/* 0x14 */
> +	"L2.transmitwake",		/* 0x15 */
> +	"disable",			/* 0x16 */
> +	"loopback.entry",		/* 0x17 */
> +	"loopback.active",		/* 0x18 */
> +	"loopback.exit",		/* 0x19 */
> +	"hotreset",			/* 0x1A */
> +};
> +
>  /**
>   * mtk_pcie_config_tlp_header() - Configure a configuration TLP header
>   * @bus: PCI bus to query
> @@ -327,8 +358,16 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
>  				 !!(val & PCIE_PORT_LINKUP), 20,
>  				 PCI_PM_D3COLD_WAIT * USEC_PER_MSEC);
>  	if (err) {
> +		const char *ltssm_state;
> +		int ltssm_index;
> +
>  		val = readl_relaxed(pcie->base + PCIE_LTSSM_STATUS_REG);
> -		dev_err(pcie->dev, "PCIe link down, ltssm reg val: %#x\n", val);
> +		ltssm_index = PCIE_LTSSM_STATE(val);
> +		ltssm_state = ltssm_index >= ARRAY_SIZE(ltssm_str) ?
> +			      "Unknown state" : ltssm_str[ltssm_index];
> +		dev_err(pcie->dev,
> +			"PCIe link down, current ltssm state: %s (%#x)\n",
> +			ltssm_state, val);
>  		return err;
>  	}
>  
> -- 
> 2.18.0
> 
> 
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