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

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Message-ID: <32f5308e629cef3692c57c4c55442b0f2f25634f.camel@mediatek.com>
Date:   Fri, 22 Apr 2022 14:33:56 +0800
From:   Jianjun Wang <jianjun.wang@...iatek.com>
To:     Ryder Lee <ryder.lee@...iatek.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-pci@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <jieyy.yang@...iatek.com>,
        <chuanjia.liu@...iatek.com>, <qizhong.cheng@...iatek.com>,
        <jian.yang@...iatek.com>
Subject: Re: [PATCH v2] PCI: mediatek-gen3: Print LTSSM state when PCIe link
 down

Hi Maintainers,

Just gentle ping for this patch, if there is anything I can do to get
this patch merged, please let me know.

Thanks.

On Tue, 2022-03-29 at 11:07 +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@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@...labora.com>
> ---
> Changes in v2:
> Print both of the register value and the LTSSM state.
> ---
>  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;
>  	}
>