linux-kernel - Re: [PATCH] misc: eeprom: at24: Always append device id even if label property is set.

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Date:   Mon, 5 Jul 2021 19:50:49 +0300
From:   Alexander Fomichev <fomichev.ru@...il.com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Jérôme Glisse <jglisse@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Diego Santa Cruz <Diego.SantaCruz@...netix.com>,
        Jon Hunter <jonathanh@...dia.com>,
        "Stable # 4 . 20+" <stable@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>, linux@...ro.com
Subject: Re: [PATCH] misc: eeprom: at24: Always append device id even if label
 property is set.

The proposed patch has been tested and it solves the problem.
Thanks.

Tested-by: Alexander Fomichev <fomichev.ru@...il.com>

чт, 1 июл. 2021 г. в 19:47, Bartosz Golaszewski <bgolaszewski@...libre.com>:
>
> On Thu, Jul 1, 2021 at 5:28 PM <jglisse@...hat.com> wrote:
> >
> > From: Jérôme Glisse <jglisse@...hat.com>
> >
> > We need to append device id even if eeprom have a label property set as some
> > platform can have multiple eeproms with same label and we can not register
> > each of those with same label. Failing to register those eeproms trigger
> > cascade failures on such platform (system is no longer working).
> >
> > This fix regression on such platform introduced with 4e302c3b568e
> >
> > Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
> > Cc: Diego Santa Cruz <Diego.SantaCruz@...netix.com>
> > Cc: Bartosz Golaszewski <bgolaszewski@...libre.com>
> > Cc: Jon Hunter <jonathanh@...dia.com>
> > Cc: stable@...r.kernel.org
> > Cc: linux-i2c@...r.kernel.org
> > ---
> >  drivers/misc/eeprom/at24.c | 17 +++++++----------
> >  1 file changed, 7 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> > index 7a6f01ace78a..305ffad131a2 100644
> > --- a/drivers/misc/eeprom/at24.c
> > +++ b/drivers/misc/eeprom/at24.c
> > @@ -714,23 +714,20 @@ static int at24_probe(struct i2c_client *client)
> >         }
> >
> >         /*
> > -        * If the 'label' property is not present for the AT24 EEPROM,
> > -        * then nvmem_config.id is initialised to NVMEM_DEVID_AUTO,
> > -        * and this will append the 'devid' to the name of the NVMEM
> > -        * device. This is purely legacy and the AT24 driver has always
> > -        * defaulted to this. However, if the 'label' property is
> > -        * present then this means that the name is specified by the
> > -        * firmware and this name should be used verbatim and so it is
> > -        * not necessary to append the 'devid'.
> > +        * We initialize nvmem_config.id to NVMEM_DEVID_AUTO even if the
> > +        * label property is set as some platform can have multiple eeproms
> > +        * with same label and we can not register each of those with same
> > +        * label. Failing to register those eeproms trigger cascade failure
> > +        * on such platform.
> >          */
> > +       nvmem_config.id = NVMEM_DEVID_AUTO;
> > +
> >         if (device_property_present(dev, "label")) {
> > -               nvmem_config.id = NVMEM_DEVID_NONE;
> >                 err = device_property_read_string(dev, "label",
> >                                                   &nvmem_config.name);
> >                 if (err)
> >                         return err;
> >         } else {
> > -               nvmem_config.id = NVMEM_DEVID_AUTO;
> >                 nvmem_config.name = dev_name(dev);
> >         }
> >
> > --
> > 2.31.1
> >
>
> Cc'ing Alexander Fomichev who reported this issue first.
>
> This is the second time someone raises this problem so it seems that
> this change really broke many existing systems. I will apply this
> patch and send it for stable.
>
> Bart



-- 
С уважением,
Александр Фомичёв.