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

Le jeu. 27 août 2020 à 15:58, Felipe Balbi <balbi@kernel.org> a
écrit :
>
> Hi,
>
> Paul Cercueil <paul@crapouillou.net> 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@crapouillou.net>
>> ---
>> 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


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