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


Le jeu. 27 août 2020 à 16:25, Felipe Balbi <balbi@kernel.org> a
écrit :
>
> Hi,
>
> Paul Cercueil <paul@crapouillou.net> 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


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