linux-kernel - Re: [PATCH v2] usb: xhci: tegra: Add shutdown callback for Tegra XUSB

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Date:   Tue, 18 Jul 2023 11:18:25 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     Haotien Hsu <haotienh@...dia.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-usb@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Wayne Chang <waynec@...dia.com>, JC Kuo <jckuo@...dia.com>,
        WK Tsai <wtsai@...dia.com>, Henry Lin <henryl@...dia.com>
Subject: Re: [PATCH v2] usb: xhci: tegra: Add shutdown callback for Tegra XUSB



On 18.07.23 11:14, Haotien Hsu wrote:
> From: Henry Lin <henryl@...dia.com>
> 
> If memory accesses by the Tegra XUSB controller are translated through
> the SMMU (System MMU), the hardware may continue accessing memory even
> after the SMMU translations have been disabled during the shutdown
> process and this can in turn cause unpredictable crashes.
> Fix this by adding a shutdown implementation that ensures the hardware
> is turned off during system reboot or shutdown.
> 
> Signed-off-by: Henry Lin <henryl@...dia.com>
> Signed-off-by: Haotien Hsu <haotienh@...dia.com>
> Acked-by: Thierry Reding <treding@...dia.com>
> 
> ---
> V1 -> V2: Resend for the typo in the mailing list
> ---
>   drivers/usb/host/xhci-tegra.c | 28 +++++++++++++++++++++-------
>   1 file changed, 21 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index a56cc81b9404..6ef2eac9835d 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -1925,6 +1925,15 @@ static int tegra_xusb_probe(struct platform_device *pdev)
>   	return err;
>   }
>   
> +static void tegra_xusb_disable(struct tegra_xusb *tegra)
> +{
> +	tegra_xusb_powergate_partitions(tegra);
> +	tegra_xusb_powerdomain_remove(tegra->dev, tegra);
> +	tegra_xusb_phy_disable(tegra);
> +	tegra_xusb_clk_disable(tegra);
> +	regulator_bulk_disable(tegra->soc->num_supplies, tegra->supplies);
> +}
> +
>   static int tegra_xusb_remove(struct platform_device *pdev)
>   {
>   	struct tegra_xusb *tegra = platform_get_drvdata(pdev);
> @@ -1947,18 +1956,22 @@ static int tegra_xusb_remove(struct platform_device *pdev)
>   
>   	pm_runtime_put(&pdev->dev);
>   
> -	tegra_xusb_powergate_partitions(tegra);
> -
> -	tegra_xusb_powerdomain_remove(&pdev->dev, tegra);
> -
> -	tegra_xusb_phy_disable(tegra);
> -	tegra_xusb_clk_disable(tegra);
> -	regulator_bulk_disable(tegra->soc->num_supplies, tegra->supplies);
> +	tegra_xusb_disable(tegra);
>   	tegra_xusb_padctl_put(tegra->padctl);
>   
>   	return 0;
>   }
>   
> +static void tegra_xusb_shutdown(struct platform_device *pdev)
> +{
> +	struct tegra_xusb *tegra = platform_get_drvdata(pdev);
> +
> +	pm_runtime_get_sync(&pdev->dev);

Where is this balanced?

	Regards
		Oliver