linux-kernel - Re: [PATCH v2 1/2] phy: usb: Fix missing elements in BCM4908 USB init array

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Message-ID: <CAH5Ym4jTidgY9MdWzHN1=30DpOSUKf_h8nXBw21XR1VFuXn6fw@mail.gmail.com>
Date: Fri, 4 Oct 2024 16:35:29 -0700
From: Sam Edwards <cfsworks@...il.com>
To: Florian Fainelli <florian.fainelli@...adcom.com>
Cc: Justin Chen <justin.chen@...adcom.com>, Al Cooper <alcooperx@...il.com>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, Vinod Koul <vkoul@...nel.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-phy@...ts.infradead.org
Subject: Re: [PATCH v2 1/2] phy: usb: Fix missing elements in BCM4908 USB init array

On Fri, Oct 4, 2024 at 9:14 AM Florian Fainelli
<florian.fainelli@...adcom.com> wrote:
>
> On 10/3/24 20:41, Sam Edwards wrote:
> > The Broadcom USB PHY driver contains a lookup table
> > (`reg_bits_map_tables`) to resolve register bitmaps unique to certain
> > versions of the USB PHY as found in various Broadcom chip families. A
> > recent commit (see 'fixes' tag) introduced two new elements to each chip
> > family in this table -- except for one: BCM4908. This resulted in the
> > xHCI controller not being initialized correctly, causing a panic on
> > boot.
>
> Yes, I think I see what happened here, we took the patch in the "fixes"
> tag from the our downstream tree, and it applied just fine, we will keep
> a closer eye on other entries in the future.
>
> >
> > The next patch will update this table to use designated initializers in
> > order to prevent this from happening again. For now, just add back the
> > missing array elements to resolve the regression.
>
> Out of curiosity, can you check whether building with
> -Wmissing-field-initializers would have caught this?

It appears that the answer is no, at least here on Clang. I also just
tried -Wextra to see if any warning would catch it and didn't see one.
My understanding is that -Wmissing-field-initializers is for struct
fields, and a construct like:
int array[3] = {1, 2};
...does not result in a warning because it's considered perfectly
valid standards-compliant C per C's default initialization rule.

Cheers,
Sam

>
> >
> > Fixes: 4536fe9640b6 ("phy: usb: suppress OC condition for 7439b2")
> > Signed-off-by: Sam Edwards <CFSworks@...il.com>
>
> Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
>
> > ---
> >   drivers/phy/broadcom/phy-brcm-usb-init.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/phy/broadcom/phy-brcm-usb-init.c b/drivers/phy/broadcom/phy-brcm-usb-init.c
> > index 39536b6d96a9..5ebb3a616115 100644
> > --- a/drivers/phy/broadcom/phy-brcm-usb-init.c
> > +++ b/drivers/phy/broadcom/phy-brcm-usb-init.c
> > @@ -220,6 +220,8 @@ usb_reg_bits_map_table[BRCM_FAMILY_COUNT][USB_CTRL_SELECTOR_COUNT] = {
> >               0, /* USB_CTRL_SETUP_SCB2_EN_MASK */
> >               0, /* USB_CTRL_SETUP_SS_EHCI64BIT_EN_MASK */
> >               0, /* USB_CTRL_SETUP_STRAP_IPP_SEL_MASK */
> > +             0, /* USB_CTRL_SETUP_OC3_DISABLE_PORT0_MASK */
> > +             0, /* USB_CTRL_SETUP_OC3_DISABLE_PORT1_MASK */
> >               0, /* USB_CTRL_SETUP_OC3_DISABLE_MASK */
> >               0, /* USB_CTRL_PLL_CTL_PLL_IDDQ_PWRDN_MASK */
> >               0, /* USB_CTRL_USB_PM_BDC_SOFT_RESETB_MASK */
>
>
> --
> Florian