linux-kernel - Re: [PATCH] usb: dwc3: meson-g12a: Add support for IRQ based OTG switching

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Date:   Tue, 11 Jun 2019 20:08:31 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     balbi@...nel.org, linux-amlogic@...ts.infradead.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] usb: dwc3: meson-g12a: Add support for IRQ based OTG switching

Hi Neil,

On Tue, Jun 11, 2019 at 3:58 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>
> Add support for the OTG ID change interrupt to switch between Host
> and Device mode.
>
> Tested on the Hardkernel Odroid-N2 board.
>
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
with the three questions/comments below answered/addressed:
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

> ---
>  drivers/usb/dwc3/dwc3-meson-g12a.c | 32 ++++++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-meson-g12a.c b/drivers/usb/dwc3/dwc3-meson-g12a.c
> index 2aec31a2eacb..e5c5ad0d529e 100644
> --- a/drivers/usb/dwc3/dwc3-meson-g12a.c
> +++ b/drivers/usb/dwc3/dwc3-meson-g12a.c
the comment block at the start of the driver file also contains a
"TOFIX" which points to the missing IRQ handling
can you please also drop that TOFIX comment in lines 15/16?

> @@ -348,6 +348,22 @@ static enum usb_role dwc3_meson_g12a_role_get(struct device *dev)
>                 USB_ROLE_HOST : USB_ROLE_DEVICE;
>  }
>
> +static irqreturn_t dwc3_meson_g12a_irq_thread(int irq, void *data)
> +{
> +       struct dwc3_meson_g12a *priv = data;
> +       enum phy_mode otg_id;
> +
> +       otg_id = dwc3_meson_g12a_get_id(priv);
> +       if (otg_id != priv->otg_phy_mode) {
> +               if (dwc3_meson_g12a_otg_mode_set(priv, otg_id))
> +                       dev_warn(priv->dev, "Failed to switch OTG mode\n");
> +       }
> +
> +       regmap_update_bits(priv->regmap, USB_R5, USB_R5_ID_DIG_IRQ, 0);
> +
> +       return IRQ_HANDLED;
> +}
> +
>  static struct device *dwc3_meson_g12_find_child(struct device *dev,
>                                                 const char *compatible)
>  {
> @@ -374,7 +390,7 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>         void __iomem *base;
>         struct resource *res;
>         enum phy_mode otg_id;
> -       int ret, i;
> +       int ret, i, irq;
>
>         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>         if (!priv)
> @@ -436,6 +452,19 @@ static int dwc3_meson_g12a_probe(struct platform_device *pdev)
>         /* Get dr_mode */
>         priv->otg_mode = usb_get_dr_mode(dev);
>
> +       if (priv->otg_mode == USB_DR_MODE_OTG) {
> +               /* Ack irq before registering */
> +               regmap_update_bits(priv->regmap, USB_R5,
> +                                  USB_R5_ID_DIG_IRQ, 0);
I assume that either the IRQ line is:
- always enabled
- enabled when (USB_R5_ID_DIG_EN_0 | USB_R5_ID_DIG_EN_1 |
USB_R5_ID_DIG_TH_MASK) are set (which we already do in
dwc3_meson_g12a_usb_init)

> +               irq = platform_get_irq(pdev, 0);
do we need to check the IRQ before trying to request it?
drivers/gpu/drm/meson/meson_dw_hdmi.c and drivers/usb/dwc3/host.c for
example error out if irq number is lower than 0

(it's great to see that this only required a small patch to make it work :))


Martin