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Subject: Re: [Linux-stm32] mtd: spinand: add spi nand mtd resume handler
From:   Patrice CHOTARD <patrice.chotard@foss.st.com>
To:     Miquel Raynal <miquel.raynal@bootlin.com>
CC:     Vignesh Raghavendra <vigneshr@ti.com>,
        <linux-kernel@vger.kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        <linux-spi@vger.kernel.org>, Mark Brown <broonie@kernel.org>,
        <linux-mtd@lists.infradead.org>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>
References: <20210526153016.32653-1-patrice.chotard@foss.st.com>
 <20210526174224.2b8714fc@xps13>
 <bbfc7b31-c49c-e52d-0ea6-20ec81317cac@foss.st.com>
Message-ID: <0072d5e7-3cf8-a8bb-569a-1ea1ba68bbae@foss.st.com>
Date:   Thu, 27 May 2021 09:32:10 +0200
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On 5/27/21 9:01 AM, Patrice CHOTARD wrote:
> Hi Miquel
> 
> On 5/26/21 5:42 PM, Miquel Raynal wrote:
>> Hello,
>>
>> <patrice.chotard@foss.st.com> wrote on Wed, 26 May 2021 17:30:16 +0200:
>>
>>> From: Christophe Kerello <christophe.kerello@foss.st.com>
>>
>> Would you mind to use "add SPI-NAND MTD resume handler" as title? (with
>> upper case letters)
> 
> Ok
> 
>>
>>> After power up, all SPI NAND's blocks are locked. Only read operations
>>> are allowed, write and erase operations are forbidden.
>>> The SPI NAND framework unlocks all the blocks during its initialization.
>>>
>>> During a standby low power, the memory is powered down, losing its
>>> configuration.
>>> During the resume, the QSPI driver state is restored but the SPI NAND
>>> framework does not reconfigured the memory.
>>>
>>> This patch adds spi nand mtd PM handlers for resume ops.
>>
>> ditto             ^^^^^^^^^^^^
> 
> Ok
> 
>>
>>> SPI NAND resume op re-initializes SPI NAND flash to its probed state.
>>>
>>> Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
>>> Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
>>> ---
>>>  drivers/mtd/nand/spi/core.c | 56 +++++++++++++++++++++++++++++++++++++
>>>  1 file changed, 56 insertions(+)
>>>
>>> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
>>> index 17f63f95f4a2..6abaf874eb3f 100644
>>> --- a/drivers/mtd/nand/spi/core.c
>>> +++ b/drivers/mtd/nand/spi/core.c
>>> @@ -1074,6 +1074,61 @@ static int spinand_detect(struct spinand_device *spinand)
>>>  	return 0;
>>>  }
>>>  
>>> +static void spinand_mtd_resume(struct mtd_info *mtd)
>>> +{
>>> +	struct spinand_device *spinand = mtd_to_spinand(mtd);
>>> +	struct nand_device *nand = mtd_to_nanddev(mtd);
>>> +	struct device *dev = &spinand->spimem->spi->dev;
>>> +	int ret, i;
>>> +
>>> +	ret = spinand_reset_op(spinand);
>>> +	if (ret)
>>> +		return;
>>> +
>>> +	ret = spinand_init_quad_enable(spinand);
>>> +	if (ret) {
>>> +		dev_err(dev,
>>> +			"Failed to initialize the quad part (err = %d)\n",
>>
>> quad part? what about "Failed to resume the quad state" or something
>> alike?
> 
> Agree, i will update this

I will even remove the dev_err(), as in spinand_init() 
no dev_err() was added on spinand_init_quad_enable() error.

> 
>>
>>> +			ret);
>>> +		return;
>>> +	}
>>> +
>>> +	ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
>>> +	if (ret) {
>>> +		dev_err(dev,
>>> +			"Failed to updtae the OTP (err = %d)\n",
>>
>> update
> 
> ok

ditto

> 
>>
>>> +			ret);
>>> +		return;
>>> +	}
>>> +
>>> +	ret = spinand_manufacturer_init(spinand);
>>> +	if (ret) {
>>> +		dev_err(dev,
>>> +			"Failed to initialize the SPI NAND chip (err = %d)\n",
>>> +			ret);
>>> +		return;
>>> +	}
>>> +
>>> +	/* After power up, all blocks are locked, so unlock them here. */
>>> +	for (i = 0; i < nand->memorg.ntargets; i++) {
>>> +		ret = spinand_select_target(spinand, i);
>>> +		if (ret) {
>>> +			dev_err(dev,
>>> +				"Failed to select the target (err = %d)\n",
>>> +				ret);

ditto

>>> +			return;
>>> +		}
>>> +
>>> +		ret = spinand_lock_block(spinand, BL_ALL_UNLOCKED);
>>> +		if (ret) {
>>> +			dev_err(dev,
>>> +				"Failed to unlock block (err = %d)\n",
>>> +				ret);

ditto

>>> +			return;
>>> +		}
>>> +	}
>>
>> I bet this would deserve a helper as this is the exact same peace of
>> code that is being run in spinnand_init()?
> 
> I will add a new function spinand_block_unlock(struct spinand_device *spinand)
> 
>>
>> At the very least I think that spinand_ecc_enable(spinand, false);
>> should be called.
> I will add it. 
> 
>>
>> Ideally, a resume operation should be provided by ECC engines, but that
>> can be added later.
>>
>>> +}
>>> +
>>>  static int spinand_init(struct spinand_device *spinand)
>>>  {
>>>  	struct device *dev = &spinand->spimem->spi->dev;
>>> @@ -1167,6 +1222,7 @@ static int spinand_init(struct spinand_device *spinand)
>>>  	mtd->_block_isreserved = spinand_mtd_block_isreserved;
>>>  	mtd->_erase = spinand_mtd_erase;
>>>  	mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
>>> +	mtd->_resume = spinand_mtd_resume;
>>>  
>>>  	if (nand->ecc.engine) {
>>>  		ret = mtd_ooblayout_count_freebytes(mtd);
>>
>> Thanks,
>> Miquèl
>>
> Thanks
> Patrice
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