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

[Paul Cercueil]

Le jeu. 27 août 2020 à 16:25, Felipe Balbi <balbi@xxxxxxxxxx> a 
écrit :
> Hi,
>
> Paul Cercueil <paul@xxxxxxxxxxxxxxx> writes:
> > > >   @@ -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.
>
> there's a difference between making a bug fix and reworking the 
> behavior
> of the driver ;-)

The one-liner is actually what changes the behavior of the driver, 
since previously the code did not read back the register.

In this case I guess it's fine, because the register does not have 
volatile bits.

> > > >   @@ -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.
>
> why so angry? Take a break every once in a while. Besides, someone 
> else
> already sent the oneliner before you ;-)

I'm just pissed that this patch has not been tested. I don't like 
sloppy work.

> In any case, why should I wait for your Reviewed-by? Get maintainer
> doesn't list you as the maintainer for it. Do you want to update
> MAINTAINERS by any chance?

Yes, I thought I was (I'm maintainer of all Ingenic drivers), that also 
explains why I wasn't Cc'd for the oneliner patch you mentioned...

IIRC Zhou has a patch to move the driver to drivers/phy/, I'll add 
myself as maintainer once it's moved there.

-Paul