linux-kernel - Re: [PATCH 1/2] PCI: tegra: Fix CLKREQ dependency programming

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Message-ID: <20191016161920.GA2526111@ulmo>
Date:   Wed, 16 Oct 2019 18:19:20 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Vidya Sagar <vidyas@...dia.com>
Cc:     lorenzo.pieralisi@....com, bhelgaas@...gle.com, robh+dt@...nel.org,
        jonathanh@...dia.com, andrew.murray@....com,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kthota@...dia.com,
        mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH 1/2] PCI: tegra: Fix CLKREQ dependency programming

On Sat, Oct 05, 2019 at 10:12:11PM +0530, Vidya Sagar wrote:
> Corrects the programming to provide REFCLK to the downstream device
> when there is no CLKREQ sideband signal routing present from root port
> to the endpont.
> 
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> ---
>  drivers/pci/controller/dwc/pcie-tegra194.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index f89f5acee72d..cbe95f0ea0ca 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -40,8 +40,6 @@
>  #define APPL_PINMUX_CLKREQ_OVERRIDE		BIT(3)
>  #define APPL_PINMUX_CLK_OUTPUT_IN_OVERRIDE_EN	BIT(4)
>  #define APPL_PINMUX_CLK_OUTPUT_IN_OVERRIDE	BIT(5)
> -#define APPL_PINMUX_CLKREQ_OUT_OVRD_EN		BIT(9)
> -#define APPL_PINMUX_CLKREQ_OUT_OVRD		BIT(10)
>  
>  #define APPL_CTRL				0x4
>  #define APPL_CTRL_SYS_PRE_DET_STATE		BIT(6)
> @@ -1193,8 +1191,8 @@ static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
>  
>  	if (!pcie->supports_clkreq) {
>  		val = appl_readl(pcie, APPL_PINMUX);
> -		val |= APPL_PINMUX_CLKREQ_OUT_OVRD_EN;
> -		val |= APPL_PINMUX_CLKREQ_OUT_OVRD;
> +		val |= APPL_PINMUX_CLKREQ_OVERRIDE_EN;
> +		val &= ~APPL_PINMUX_CLKREQ_OVERRIDE;
>  		appl_writel(pcie, val, APPL_PINMUX);
>  	}

If we do support CLKREQ, do we have to explicitly set the OVERRIDE bit?
Or clear the OVERRIDE_EN bit? Is it always guaranteed that the defaults
(OVERRIDE_EN = 0) is applied at this point?

That's an issue that's orthogonal to this patch, though, so for this
one:

Acked-by: Thierry Reding <treding@...dia.com>

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