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

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Hi

在 2020/8/27 下午9:50, Paul Cercueil 写道:


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.

This is my fault. This error occurred in the v5 version, but was corrected in the v6 version, but I don't know why v5 was merged into the mainline and v6 was not merged, which caused this problem.


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...

I checked again, get_maintainer did not give the correct information, which caused my script to not add Paul to the cc list.
IIRC Zhou has a patch to move the driver to drivers/phy/, I'll add myself as maintainer once it's moved there.

I'll resend it soon.


Thanks and best regards!

-Paul




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