linux-kernel - Re: [PATCH] PCI: qcom: Make sure PCIe is reset before init for rev 2.1.0

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Date:   Tue, 1 Sep 2020 11:55:34 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Stanimir Varbanov <svarbanov@...sol.com>, stable@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: qcom: Make sure PCIe is reset before init for rev
 2.1.0

On Tue 01 Sep 07:49 CDT 2020, Ansuel Smith wrote:

> Qsdk U-Boot can incorrectly leave the PCIe interface in an undefined
> state if bootm command is used instead of bootipq. This is caused by the
> not deinit of PCIe when bootm is called. Reset the PCIe before init
> anyway to fix this U-Boot bug.
> 

Looks sensible.

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Regards,
Bjorn

> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
> Cc: stable@...r.kernel.org # v4.19+
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 3aac77a295ba..82336bbaf8dc 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -302,6 +302,9 @@ static void qcom_pcie_deinit_2_1_0(struct qcom_pcie *pcie)
>  	reset_control_assert(res->por_reset);
>  	reset_control_assert(res->ext_reset);
>  	reset_control_assert(res->phy_reset);
> +
> +	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
> +
>  	regulator_bulk_disable(ARRAY_SIZE(res->supplies), res->supplies);
>  }
>  
> @@ -314,6 +317,16 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
>  	u32 val;
>  	int ret;
>  
> +	/* reset the PCIe interface as uboot can leave it undefined state */
> +	reset_control_assert(res->pci_reset);
> +	reset_control_assert(res->axi_reset);
> +	reset_control_assert(res->ahb_reset);
> +	reset_control_assert(res->por_reset);
> +	reset_control_assert(res->ext_reset);
> +	reset_control_assert(res->phy_reset);
> +
> +	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
> +
>  	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res->supplies);
>  	if (ret < 0) {
>  		dev_err(dev, "cannot enable regulators\n");
> -- 
> 2.27.0
>