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Date:   Fri, 24 Jun 2022 12:11:11 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Krishna chaitanya chundru <quic_krichai@quicinc.com>
Cc:     linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, quic_vbadigan@quicinc.com,
        quic_hemantk@quicinc.com, quic_nitegupt@quicinc.com,
        quic_skananth@quicinc.com, quic_ramkri@quicinc.com,
        manivannan.sadhasivam@linaro.org, swboyd@chromium.org,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Stanimir Varbanov <svarbanov@mm-sol.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v2] PCI: qcom: Allow L1 and its sub states
Message-ID: <20220624171111.GA1542083@bhelgaas>
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On Wed, Jun 15, 2022 at 06:45:39PM +0530, Krishna chaitanya chundru wrote:
> Allow L1 and its sub-states in the qcom pcie driver.
> By default this is disabled in the hardware. So enabling it explicitly.
> 
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>

I have a vague memory of my questions at [1] being answered, but I
don't see the answers on the mailing list.  Maybe I missed it?

We should expand the commit log a bit with those details.

I'm also hoping for an ack from Stanimir, Andy, or Bjorn A., since
they're listed as maintainers of this driver.

[1] https://lore.kernel.org/r/20220615154422.GA941075@bhelgaas

> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 6ab9089..0d8efcc 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -41,6 +41,9 @@
>  #define L23_CLK_RMV_DIS				BIT(2)
>  #define L1_CLK_RMV_DIS				BIT(1)
>  
> +#define PCIE20_PARF_PM_CTRL			0x20
> +#define REQ_NOT_ENTR_L1				BIT(5)
> +
>  #define PCIE20_PARF_PHY_CTRL			0x40
>  #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK	GENMASK(20, 16)
>  #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x)		((x) << 16)
> @@ -1267,6 +1270,11 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
>  	val |= BIT(4);
>  	writel(val, pcie->parf + PCIE20_PARF_MHI_CLOCK_RESET_CTRL);
>  
> +	/* Enable L1 and L1ss */
> +	val = readl(pcie->parf + PCIE20_PARF_PM_CTRL);
> +	val &= ~REQ_NOT_ENTR_L1;
> +	writel(val, pcie->parf + PCIE20_PARF_PM_CTRL);
> +
>  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
>  		val = readl(pcie->parf + PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT);
>  		val |= BIT(31);
> -- 
> 2.7.4
>