Re: [PATCH 1/1] USB: PHY: JZ4770: Fix uninitialized value written to HW register

[Paul Cercueil]

Hi Felipe,

Le jeu. 27 août 2020 à 15:58, Felipe Balbi <balbi@xxxxxxxxxx> a 
écrit :
> Hi,
>
> Paul Cercueil <paul@xxxxxxxxxxxxxxx> writes:
> >  The 'reg' value was written to a hardware register in
> >  ingenic_usb_phy_init(), while not being initialized anywhere.
>
> your patch does a lot more than fix the bug :-)
>
> >  Fixes: 2a6c0b82e651 ("USB: PHY: JZ4770: Add support for new Ingenic 
> > SoCs.")
> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >   drivers/usb/phy/phy-jz4770.c | 28 +++++++++++-----------------
> >   1 file changed, 11 insertions(+), 17 deletions(-)
> >
> >  diff --git a/drivers/usb/phy/phy-jz4770.c 
> > b/drivers/usb/phy/phy-jz4770.c
> >  index d4ee3cb721ea..58771a8688f2 100644
> >  --- a/drivers/usb/phy/phy-jz4770.c
> >  +++ b/drivers/usb/phy/phy-jz4770.c
> >  @@ -97,7 +97,7 @@ enum ingenic_usb_phy_version {
> >   struct ingenic_soc_info {
> >   	enum ingenic_usb_phy_version version;
> >
> >  -	void (*usb_phy_init)(struct usb_phy *phy);
> >  +	u32 (*usb_phy_init)(struct usb_phy *phy);
>
> this is not fixing any bug
>
> >  @@ -172,7 +172,8 @@ static int ingenic_usb_phy_init(struct usb_phy 
> > *phy)
> >   		return err;
> >   	}
> >
> >  -	priv->soc_info->usb_phy_init(phy);
> >  +	reg = priv->soc_info->usb_phy_init(phy);
> >  +	writel(reg, priv->base + REG_USBPCR_OFFSET);
>
> not fixing any bug.
>
> Looking at the code, the bug follows after this line. It would suffice
> to read REG_USBPCR_OFFSET in order to initialize reg. This bug fix 
> could
> have been a one liner.

There's no need to re-read a register when you have the value readily 
available. It just needs to be returned from the usb_phy_init 
callbacks. But yes, it's not a one-liner.

> >  @@ -195,19 +196,15 @@ static void ingenic_usb_phy_remove(void *phy)
> >   	usb_remove_phy(phy);
> >   }
> >
> >  -static void jz4770_usb_phy_init(struct usb_phy *phy)
> >  +static u32 jz4770_usb_phy_init(struct usb_phy *phy)
>
> not a bug fix
>
> >   {
> >  -	struct jz4770_phy *priv = phy_to_jz4770_phy(phy);
> >  -	u32 reg;
> >  -
> >  -	reg = USBPCR_AVLD_REG | USBPCR_COMMONONN | USBPCR_IDPULLUP_ALWAYS 
> > |
> >  +	return USBPCR_AVLD_REG | USBPCR_COMMONONN | 
> > USBPCR_IDPULLUP_ALWAYS |
> >   		USBPCR_COMPDISTUNE_DFT | USBPCR_OTGTUNE_DFT | 
> > USBPCR_SQRXTUNE_DFT |
> >   		USBPCR_TXFSLSTUNE_DFT | USBPCR_TXRISETUNE_DFT | 
> > USBPCR_TXVREFTUNE_DFT |
> >   		USBPCR_POR;
> >  -	writel(reg, priv->base + REG_USBPCR_OFFSET);
>
> not a bug fix
>
> >   }
> >
> >  -static void jz4780_usb_phy_init(struct usb_phy *phy)
> >  +static u32 jz4780_usb_phy_init(struct usb_phy *phy)
>
> not a bug fix
>
> >  @@ -216,11 +213,10 @@ static void jz4780_usb_phy_init(struct 
> > usb_phy *phy)
> >   		USBPCR1_WORD_IF_16BIT;
> >   	writel(reg, priv->base + REG_USBPCR1_OFFSET);
> >
> >  -	reg = USBPCR_TXPREEMPHTUNE | USBPCR_COMMONONN | USBPCR_POR;
> >  -	writel(reg, priv->base + REG_USBPCR_OFFSET);
> >  +	return USBPCR_TXPREEMPHTUNE | USBPCR_COMMONONN | USBPCR_POR;
>
> not a bug fix
>
> >   }
> >
> >  -static void x1000_usb_phy_init(struct usb_phy *phy)
> >  +static u32 x1000_usb_phy_init(struct usb_phy *phy)
>
> not a bug fix
>
> >   {
> >   	struct jz4770_phy *priv = phy_to_jz4770_phy(phy);
> >   	u32 reg;
> >  @@ -228,13 +224,12 @@ static void x1000_usb_phy_init(struct usb_phy 
> > *phy)
> >   	reg = readl(priv->base + REG_USBPCR1_OFFSET) | 
> > USBPCR1_WORD_IF_16BIT;
> >   	writel(reg, priv->base + REG_USBPCR1_OFFSET);
> >
> >  -	reg = USBPCR_SQRXTUNE_DCR_20PCT | USBPCR_TXPREEMPHTUNE |
> >  +	return USBPCR_SQRXTUNE_DCR_20PCT | USBPCR_TXPREEMPHTUNE |
> >   		USBPCR_TXHSXVTUNE_DCR_15MV | USBPCR_TXVREFTUNE_INC_25PPT |
> >   		USBPCR_COMMONONN | USBPCR_POR;
> >  -	writel(reg, priv->base + REG_USBPCR_OFFSET);
>
> not a bug fix
>
> >   }
> >
> >  -static void x1830_usb_phy_init(struct usb_phy *phy)
> >  +static u32 x1830_usb_phy_init(struct usb_phy *phy)
>
> not a bug fix
>
> >   {
> >   	struct jz4770_phy *priv = phy_to_jz4770_phy(phy);
> >   	u32 reg;
> >  @@ -246,9 +241,8 @@ static void x1830_usb_phy_init(struct usb_phy 
> > *phy)
> >   		USBPCR1_DMPD | USBPCR1_DPPD;
> >   	writel(reg, priv->base + REG_USBPCR1_OFFSET);
> >
> >  -	reg = USBPCR_IDPULLUP_OTG | USBPCR_VBUSVLDEXT 
> > |	USBPCR_TXPREEMPHTUNE |
> >  +	return USBPCR_IDPULLUP_OTG | USBPCR_VBUSVLDEXT | 
> > USBPCR_TXPREEMPHTUNE |
> >   		USBPCR_COMMONONN | USBPCR_POR;
> >  -	writel(reg, priv->base + REG_USBPCR_OFFSET);
>
> not a bug fix

Well, if you don't like my bug fix, next time wait for my Reviewed-by.

Cheers,
-Paul