Linux-PHY Archive on lore.kernel.org

* Re: [PATCH] phy: renesas: rcar-gen3-usb2: Simplify ID/VBUS detection logic
From: Geert Uytterhoeven @ 2026-03-24 13:05 UTC (permalink / raw)
  To: Prabhakar
  Cc: Yoshihiro Shimoda, Vinod Koul, Neil Armstrong, Magnus Damm,
	Pavel Machek, linux-renesas-soc, linux-phy, linux-kernel,
	Biju Das, Fabrizio Castro, Lad Prabhakar
In-Reply-To: <20260324121608.3444943-1-prabhakar.mahadev-lad.rj@bp.renesas.com>

Hi Prabhakar,

On Tue, 24 Mar 2026 at 13:16, Prabhakar <prabhakar.csengg@gmail.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> Read the USB2_ADPCTRL register once in rcar_gen3_check_id() and reuse
> the value instead of performing multiple MMIO reads.
>
> Simplify the return logic by comparing the IDDIG and VBUSVALID bits
> directly. This preserves the existing behaviour while improving code
> clarity and avoiding redundant register accesses.
>
> Reported-by: Pavel Machek <pavel@nabladev.com>
> Closes: https://lore.kernel.org/all/acJV-Xq-2uq_JFMn@duo.ucw.cz/
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> +++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
> @@ -314,13 +314,14 @@ static void rcar_gen3_init_from_a_peri_to_a_host(struct rcar_gen3_chan *ch)
>  static bool rcar_gen3_check_id(struct rcar_gen3_chan *ch)
>  {
>         if (ch->phy_data->vblvl_ctrl) {
> +               u32 val = readl(ch->base + USB2_ADPCTRL);
>                 bool vbus_valid;
>                 bool device;
>
> -               device = !!(readl(ch->base + USB2_ADPCTRL) & USB2_ADPCTRL_IDDIG);
> -               vbus_valid = !!(readl(ch->base + USB2_ADPCTRL) & USB2_ADPCTRL_VBUSVALID);
> +               device = !!(val & USB2_ADPCTRL_IDDIG);
> +               vbus_valid = !!(val & USB2_ADPCTRL_VBUSVALID);

Perhaps combine variable declarations and assignments?
The "!!" is not needed when assigning to a bool.

>
> -               return vbus_valid ? device : !device;
> +               return device == vbus_valid;
>         }
>
>         if (!ch->uses_otg_pins)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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