linux-kernel - Re: [PATCH v3 01/11] PCI: imx6: Fix PCIe link down when i.MX8MM and i.MX8MP PCIe is EP mode

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Date: Sat, 27 Apr 2024 14:30:57 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.Li@....com>
Cc: Richard Zhu <hongxing.zhu@....com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	NXP Linux Team <linux-imx@....com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-pci@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v3 01/11] PCI: imx6: Fix PCIe link down when i.MX8MM and
 i.MX8MP PCIe is EP mode

On Tue, Apr 02, 2024 at 10:33:37AM -0400, Frank Li wrote:
> From: Richard Zhu <hongxing.zhu@....com>
> 
> Both IMX8MM_EP and IMX8MP_EP have the "IMX6_PCIE_FLAG_HAS_APP_RESET"
> set indeed. Otherwise, the LTSSM_EN bit wouldn't be asserted anymore.
> That's the root cause that PCIe link is down when i.MX8MM and i.MX8MP
> PCIe are in the EP mode.
> 

This commit message is difficult to understand. I think the issue you are fixing
is that these 2 SoCs do not control the 'apps_reset', due to which the LTSSM
state is not configured properly.

Referring Link Down is confusing at its best. Is the link training happens first
of all?

- Mani

> Fixes: 0c9651c21f2a ("PCI: imx6: Simplify reset handling by using *_FLAG_HAS_*_RESET")
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 99a60270b26cd..e43eda6b33ca7 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1568,7 +1568,8 @@ static const struct imx6_pcie_drvdata drvdata[] = {
>  	},
>  	[IMX8MM_EP] = {
>  		.variant = IMX8MM_EP,
> -		.flags = IMX6_PCIE_FLAG_HAS_PHYDRV,
> +		.flags = IMX6_PCIE_FLAG_HAS_APP_RESET |
> +			 IMX6_PCIE_FLAG_HAS_PHYDRV,
>  		.mode = DW_PCIE_EP_TYPE,
>  		.gpr = "fsl,imx8mm-iomuxc-gpr",
>  		.clk_names = imx8mm_clks,
> @@ -1579,7 +1580,8 @@ static const struct imx6_pcie_drvdata drvdata[] = {
>  	},
>  	[IMX8MP_EP] = {
>  		.variant = IMX8MP_EP,
> -		.flags = IMX6_PCIE_FLAG_HAS_PHYDRV,
> +		.flags = IMX6_PCIE_FLAG_HAS_APP_RESET |
> +			 IMX6_PCIE_FLAG_HAS_PHYDRV,
>  		.mode = DW_PCIE_EP_TYPE,
>  		.gpr = "fsl,imx8mp-iomuxc-gpr",
>  		.clk_names = imx8mm_clks,
> 
> -- 
> 2.34.1
> 

-- 
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