linux-kernel - Re: mtd: spinand: add spi nand mtd resume handler

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Message-ID: <bbfc7b31-c49c-e52d-0ea6-20ec81317cac@foss.st.com>
Date:   Thu, 27 May 2021 09:01:55 +0200
From:   Patrice CHOTARD <patrice.chotard@...s.st.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
CC:     Mark Brown <broonie@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        <linux-mtd@...ts.infradead.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <christophe.kerello@...s.st.com>
Subject: Re: mtd: spinand: add spi nand mtd resume handler

Hi Miquel

On 5/26/21 5:42 PM, Miquel Raynal wrote:
> Hello,
> 
> <patrice.chotard@...s.st.com> wrote on Wed, 26 May 2021 17:30:16 +0200:
> 
>> From: Christophe Kerello <christophe.kerello@...s.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@...s.st.com>
>> Signed-off-by: Patrice Chotard <patrice.chotard@...s.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

> 
>> +			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

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