linux-kernel - Re: [PATCH] Revert "usb: dwc3: meson-g12a: fix shared reset control use"

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Date:   Thu, 27 Aug 2020 16:54:30 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Amjad Ouled-Ameur <aouledameur@...libre.com>,
        Felipe Balbi <balbi@...nel.org>
Cc:     Dan Robertson <dan@...obertson.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "usb: dwc3: meson-g12a: fix shared reset control
 use"

On 27/08/2020 16:48, Amjad Ouled-Ameur wrote:
> This reverts commit 7a410953d1fb4dbe91ffcfdee9cbbf889d19b0d7.
> 
> This commit breaks USB on meson-gxl-s905x-libretech-cc. Reverting
> the change solves the issue.
> 
> In fact, according to the reset framework code, consumers must not use
> reset_control_(de)assert() on shared reset lines when reset_control_reset
> has been used, and vice-versa.
> 
> Moreover, with this commit, usb is not guaranted to be reset since the
> reset is likely to be initially deasserted.
> 
> Reverting the commit will bring back the suspend warning mentioned in the
> commit description. Nevertheless, a warning is much less critical than
> breaking dwc3-meson-g12a USB completely. We will address the warning
> issue in another way as a 2nd step.
> 
> Signed-off-by: Amjad Ouled-Ameur <aouledameur@...libre.com>
> Reported-by: Jerome Brunet <jbrunet@...libre.com>
> ---
>  drivers/usb/dwc3/dwc3-meson-g12a.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-meson-g12a.c b/drivers/usb/dwc3/dwc3-meson-g12a.c
> index 88b75b5a039c..1f7f4d88ed9d 100644
> --- a/drivers/usb/dwc3/dwc3-meson-g12a.c
> +++ b/drivers/usb/dwc3/dwc3-meson-g12a.c
> @@ -737,13 +737,13 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>  		goto err_disable_clks;
>  	}
>  
> -	ret = reset_control_deassert(priv->reset);
> +	ret = reset_control_reset(priv->reset);
>  	if (ret)
> -		goto err_assert_reset;
> +		goto err_disable_clks;
>  
>  	ret = dwc3_meson_g12a_get_phys(priv);
>  	if (ret)
> -		goto err_assert_reset;
> +		goto err_disable_clks;
>  
>  	ret = priv->drvdata->setup_regmaps(priv, base);
>  	if (ret)
> @@ -752,7 +752,7 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>  	if (priv->vbus) {
>  		ret = regulator_enable(priv->vbus);
>  		if (ret)
> -			goto err_assert_reset;
> +			goto err_disable_clks;
>  	}
>  
>  	/* Get dr_mode */
> @@ -765,13 +765,13 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>  
>  	ret = priv->drvdata->usb_init(priv);
>  	if (ret)
> -		goto err_assert_reset;
> +		goto err_disable_clks;
>  
>  	/* Init PHYs */
>  	for (i = 0 ; i < PHY_COUNT ; ++i) {
>  		ret = phy_init(priv->phys[i]);
>  		if (ret)
> -			goto err_assert_reset;
> +			goto err_disable_clks;
>  	}
>  
>  	/* Set PHY Power */
> @@ -809,9 +809,6 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>  	for (i = 0 ; i < PHY_COUNT ; ++i)
>  		phy_exit(priv->phys[i]);
>  
> -err_assert_reset:
> -	reset_control_assert(priv->reset);
> -
>  err_disable_clks:
>  	clk_bulk_disable_unprepare(priv->drvdata->num_clks,
>  				   priv->drvdata->clks);
> 

Acked-by: Neil Armstrong <narmstrong@...libre.com>