linux-kernel - Re: [PATCH] - change calculating of position page containing BBM

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Message-ID: <20190923121337.GA15230@global.cadence.com>
Date:   Mon, 23 Sep 2019 13:13:39 +0100
From:   Piotr Sroka <piotrs@...ence.com>
To:     Schrempf Frieder <frieder.schrempf@...tron.de>
CC:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] - change calculating of position page containing BBM

Hello

The 09/19/2019 13:33, Schrempf Frieder wrote:
>EXTERNAL MAIL
>
>
>On 19.09.19 15:18, Miquel Raynal wrote:
>> Hello,
>>
>> Schrempf Frieder <frieder.schrempf@...tron.de> wrote on Thu, 19 Sep
>> 2019 13:15:08 +0000:
>>
>>> On 19.09.19 14:58, Miquel Raynal wrote:
>>>> Hi Piotr,
>>>>
>>>> Piotr Sroka <piotrs@...ence.com> wrote on Thu, 19 Sep 2019 13:41:35
>>>> +0100:
>>>>
>>>>> Change calculating of position page containing BBM
>>>>>
>>>>> If none of BBM flags is set then function nand_bbm_get_next_page
>>>>> reports EINVAL. It causes that BBM is not read at all during scanning
>>>>> factory bad blocks. The result is that the BBT table is build without
>>>>> checking factory BBM at all. For Micron flash memories none of this
>>>>> flag is set if page size is different than 2048 bytes.
>>>
>>> I wonder if it wouldn't be better to fix the Micron driver instead:
>>>
>>> --- a/drivers/mtd/nand/raw/nand_micron.c
>>> +++ b/drivers/mtd/nand/raw/nand_micron.c
>>> @@ -448,6 +448,8 @@ static int micron_nand_init(struct nand_chip *chip)
>>>
>>>           if (mtd->writesize == 2048)
>>>                   chip->options |= NAND_BBM_FIRSTPAGE |
>>>                                    NAND_BBM_SECONDPAGE;
>>> +       else
>>> +               chip->options |= NAND_BBM_FIRSTPAGE;
>>
>> That's what I forgot in my last answer to this thread, I think I only
>> told Piotr privately: I would like both. I think it is important to fix
>> the bbm_get_next_page function but for clarity, setting the FIRSTPAGE
>> flag in Micron's driver seems also pertinent.
>
>Indeed, that sounds reasonable. Piotr, can you send another patch with
>the diff above? And by the way: thanks for fixing my code ;)
>
>Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>
>
Thanks Frieder and Miquel for the very quick reply. I will send next
version containing Micron driver fix.

>>
>>>
>>>           ondie = micron_supports_on_die_ecc(chip);
>>>
>>>
>>>>
>>>> "none of these flags are set"
>>>>
>>>>>
>>>>> This patch changes the nand_bbm_get_next_page function.
>>>>
>>>> "Address this regression by changing the
>>>> nand_bbm_get_next_page_function."
>>>>
>>>>> It will return 0 if none of BBM flag is set and page parameter is 0.
>>>>
>>>>                         no BBM flag is set
>>>>
>>>>> After that modification way of discovering factory bad blocks will work
>>>>> similar as in kernel version 5.1.
>>>>>
>>>>
>>>> Fixes + stable tags would be great!
Ok I will add fixes tag and "Cc: <stable@...r.kernel.org>". 

>>>>
>>>>> Signed-off-by: Piotr Sroka <piotrs@...ence.com>
>>>>> ---
>>>>>    drivers/mtd/nand/raw/nand_base.c | 8 ++++++--
>>>>>    1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
>>>>> index 5c2c30a7dffa..f64e3b6605c6 100644
>>>>> --- a/drivers/mtd/nand/raw/nand_base.c
>>>>> +++ b/drivers/mtd/nand/raw/nand_base.c
>>>>> @@ -292,12 +292,16 @@ int nand_bbm_get_next_page(struct nand_chip *chip, int page)
>>>>>    	struct mtd_info *mtd = nand_to_mtd(chip);
>>>>>    	int last_page = ((mtd->erasesize - mtd->writesize) >>
>>>>>    			 chip->page_shift) & chip->pagemask;
>>>>> +	unsigned int bbm_flags = NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE
>>>>> +		| NAND_BBM_LASTPAGE;
>>>>>
>>>>> +	if (page == 0 && !(chip->options & bbm_flags))
>>>>> +		return 0;
>>>>>    	if (page == 0 && chip->options & NAND_BBM_FIRSTPAGE)
>>>>>    		return 0;
>>>>> -	else if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
>>>>> +	if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
>>>>>    		return 1;
>>>>> -	else if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
>>>>> +	if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
>>>>>    		return last_page;
>>>>>
>>>>>    	return -EINVAL;
>>>>
>>>> Lookgs good otherwise.
>>>>
>>>> Thanks,
>>>> Miquèl
>>>>
>>
>> Thanks,
>> Miquèl
>>

Thanks,
Piotr