Messages in this thread | | | Subject | Re: [PATCH] mtd: core: handle flashes without OTP gracefully | From | Guenter Roeck <> | Date | Sat, 3 Jul 2021 10:26:06 -0700 |
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On 7/3/21 9:42 AM, Tudor.Ambarus@microchip.com wrote: > On 7/3/21 7:08 PM, Michael Walle wrote: >> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >> >> Am 3. Juli 2021 11:56:14 MESZ schrieb Tudor.Ambarus@microchip.com: >>> On 7/2/21 12:38 PM, Michael Walle wrote: >>>> EXTERNAL EMAIL: Do not click links or open attachments unless you >>> know the content is safe >>>> >>>> There are flash drivers which registers the OTP callbacks although >>> the >>>> flash doesn't support OTP regions and return -ENODATA for these >>>> callbacks if there is no OTP. If this happens, the probe of the whole >>> >>> why do they register the OTP callback if they don't support OTP? >> >> I don't know. But I certainly won't touch that code :p > > why? :D > >> >> >>>> flash will fail. Fix it by handling the ENODATA return code and skip >>>> the OTP region nvmem setup. >>>> >>>> Fixes: 4b361cfa8624 ("mtd: core: add OTP nvmem provider support") >>>> Reported-by: Guenter Roeck <linux@roeck-us.net> >>>> Signed-off-by: Michael Walle <michael@walle.cc> >>>> --- >>>> drivers/mtd/mtdcore.c | 10 ++++++++-- >>>> 1 file changed, 8 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c >>>> index b5ccd3037788..6881d1423dd6 100644 >>>> --- a/drivers/mtd/mtdcore.c >>>> +++ b/drivers/mtd/mtdcore.c >>>> @@ -880,7 +880,10 @@ static int mtd_otp_nvmem_add(struct mtd_info >>> *mtd) >>>> >>>> if (mtd->_get_user_prot_info && mtd->_read_user_prot_reg) { >>>> size = mtd_otp_size(mtd, true); >>>> - if (size < 0) >>>> + /* ENODATA means there is no OTP region */ >>>> + if (size == -ENODATA) >>> >>> If no OTP data, maybe it's more appropriate for the clients to just >>> return a retlen of 0. >> >> you mean already checking ENODATA in mtd_otp_size() and return 0. That would also make the hunk below unnecessary. I'll change it. > > I've thought about: > > diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c > index 54f92d09d9cf..9419b33d7238 100644 > --- a/drivers/mtd/chips/cfi_cmdset_0001.c > +++ b/drivers/mtd/chips/cfi_cmdset_0001.c > @@ -2314,7 +2314,7 @@ static int cfi_intelext_otp_walk(struct mtd_info *mtd, loff_t from, size_t len, > > /* Check that we actually have some OTP registers */ > if (!extp || !(extp->FeatureSupport & 64) || !extp->NumProtectionFields) > - return -ENODATA; > + return 0; >
There are various places where this is called, including code returning information to userspace. That means you'd be changing the ABI to userspace which would now suddenly return 0 instead of -ENODATA.
Guenter
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