linux-kernel - Re: [PATCH v3 2/3] mtd: spinand: use the spi-mem poll status APIs

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Date:   Tue, 18 May 2021 13:50:13 +0200
From:   Patrice CHOTARD <patrice.chotard@...s.st.com>
To:     Boris Brezillon <boris.brezillon@...labora.com>
CC:     Mark Brown <broonie@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Vignesh Raghavendra <vigneshr@...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: [PATCH v3 2/3] mtd: spinand: use the spi-mem poll status APIs

Hi 

On 5/18/21 1:28 PM, Boris Brezillon wrote:
> On Tue, 18 May 2021 11:39:50 +0200
> <patrice.chotard@...s.st.com> wrote:
> 
>> From: Patrice Chotard <patrice.chotard@...s.st.com>
>>
>> Make use of spi-mem poll status APIs to let advanced controllers
>> optimize wait operations.
> 
> This should also fix the high CPU usage you were reporting for those
> that don't have a dedicated STATUS poll block logic, which is great!

I will update the commit message by indicating what you mention here.

> 
>>
>> Signed-off-by: Patrice Chotard <patrice.chotard@...s.st.com>
>> Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>
>> ---
>> Changes in v3:
>>   - Add initial_delay_us and polling_delay_us parameters to spinand_wait()
>>   - Add SPINAND_READ/WRITE/ERASE/RESET_INITIAL_DELAY_US and
>>     SPINAND_READ/WRITE/ERASE/RESET_POLL_DELAY_US defines.
>>
>> Changes in v2:
>>   - non-offload case is now managed by spi_mem_poll_status()
>>
>>  drivers/mtd/nand/spi/core.c | 45 ++++++++++++++++++++++++++-----------
>>  include/linux/mtd/spinand.h | 11 ++++++++-
>>  2 files changed, 42 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
>> index 17f63f95f4a2..ef2a692ab5b6 100644
>> --- a/drivers/mtd/nand/spi/core.c
>> +++ b/drivers/mtd/nand/spi/core.c
>> @@ -473,20 +473,26 @@ static int spinand_erase_op(struct spinand_device *spinand,
>>  	return spi_mem_exec_op(spinand->spimem, &op);
>>  }
>>  
>> -static int spinand_wait(struct spinand_device *spinand, u8 *s)
>> +static int spinand_wait(struct spinand_device *spinand,
>> +			unsigned long initial_delay_us,
>> +			unsigned long poll_delay_us,
>> +			u8 *s)
>>  {
>> -	unsigned long timeo =  jiffies + msecs_to_jiffies(400);
>> +	struct spi_mem_op op = SPINAND_GET_FEATURE_OP(REG_STATUS,
>> +						      spinand->scratchbuf);
>>  	u8 status;
>>  	int ret;
>>  
>> -	do {
>> -		ret = spinand_read_status(spinand, &status);
>> -		if (ret)
>> -			return ret;
>> +	ret = spi_mem_poll_status(spinand->spimem, &op, STATUS_BUSY, 0,
>> +				  initial_delay_us,
>> +				  poll_delay_us,
>> +				  SPINAND_STATUS_TIMEOUT_MS);
>> +	if (ret)
>> +		return ret;
>>  
>> -		if (!(status & STATUS_BUSY))
>> -			goto out;
>> -	} while (time_before(jiffies, timeo));
>> +	status = *spinand->scratchbuf;
>> +	if (!(status & STATUS_BUSY))
>> +		goto out;
>>  
>>  	/*
>>  	 * Extra read, just in case the STATUS_READY bit has changed
>> @@ -526,7 +532,10 @@ static int spinand_reset_op(struct spinand_device *spinand)
>>  	if (ret)
>>  		return ret;
>>  
>> -	return spinand_wait(spinand, NULL);
>> +	return spinand_wait(spinand,
>> +			    SPINAND_RESET_INITIAL_DELAY_US,
>> +			    SPINAND_RESET_POLL_DELAY_US,
>> +			    NULL);
>>  }
>>  
>>  static int spinand_lock_block(struct spinand_device *spinand, u8 lock)
>> @@ -549,7 +558,10 @@ static int spinand_read_page(struct spinand_device *spinand,
>>  	if (ret)
>>  		return ret;
>>  
>> -	ret = spinand_wait(spinand, &status);
>> +	ret = spinand_wait(spinand,
>> +			   SPINAND_READ_INITIAL_DELAY_US,
>> +			   SPINAND_READ_POLL_DELAY_US,
>> +			   &status);
>>  	if (ret < 0)
>>  		return ret;
>>  
>> @@ -585,7 +597,10 @@ static int spinand_write_page(struct spinand_device *spinand,
>>  	if (ret)
>>  		return ret;
>>  
>> -	ret = spinand_wait(spinand, &status);
>> +	ret = spinand_wait(spinand,
>> +			   SPINAND_WRITE_INITIAL_DELAY_US,
>> +			   SPINAND_WRITE_POLL_DELAY_US,
>> +			   &status);
>>  	if (!ret && (status & STATUS_PROG_FAILED))
>>  		return -EIO;
>>  
>> @@ -768,7 +783,11 @@ static int spinand_erase(struct nand_device *nand, const struct nand_pos *pos)
>>  	if (ret)
>>  		return ret;
>>  
>> -	ret = spinand_wait(spinand, &status);
>> +	ret = spinand_wait(spinand,
>> +			   SPINAND_ERASE_INITIAL_DELAY_US,
>> +			   SPINAND_ERASE_POLL_DELAY_US,
>> +			   &status);
>> +
>>  	if (!ret && (status & STATUS_ERASE_FAILED))
>>  		ret = -EIO;
>>  
>> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
>> index 6bb92f26833e..180c1fa64e62 100644
>> --- a/include/linux/mtd/spinand.h
>> +++ b/include/linux/mtd/spinand.h
>> @@ -169,7 +169,16 @@
>>  struct spinand_op;
>>  struct spinand_device;
>>  
>> -#define SPINAND_MAX_ID_LEN	4
>> +#define SPINAND_MAX_ID_LEN		4
>> +#define SPINAND_READ_INITIAL_DELAY_US	6
>> +#define SPINAND_READ_POLL_DELAY_US	5
>> +#define SPINAND_RESET_INITIAL_DELAY_US	5
>> +#define SPINAND_RESET_POLL_DELAY_US	5
>> +#define SPINAND_WRITE_INITIAL_DELAY_US	75
>> +#define SPINAND_WRITE_POLL_DELAY_US	15
>> +#define SPINAND_ERASE_INITIAL_DELAY_US	250
>> +#define SPINAND_ERASE_POLL_DELAY_US	50
> 
> Could you add a comment explaining where those numbers come from?

Sure

> 
>> +#define SPINAND_STATUS_TIMEOUT_MS	400
> 
> I would name that one SPINAND_WAITRDY_TIMEOUT_MS.
Ok

> 
>>  
>>  /**
>>   * struct spinand_id - SPI NAND id structure
> 

Thanks 
Patrice