Re: [PATCH 07/13] mtd: spinand: Allow enabling Octal DTR mode in the core

From: Apurva Nandan <a-nandan@ti.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Mark Brown <broonie@kernel.org>,
	Patrice Chotard <patrice.chotard@foss.st.com>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	<linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
	<linux-spi@vger.kernel.org>, Pratyush Yadav <p.yadav@ti.com>
Subject: Re: [PATCH 07/13] mtd: spinand: Allow enabling Octal DTR mode in the core
Date: Fri, 20 Aug 2021 16:11:05 +0530	[thread overview]
Message-ID: <c3e52b84-7ffc-8e48-d0c7-f17fa0b71f6b@ti.com> (raw)
In-Reply-To: <20210806205845.03dd97c9@xps13>

Hi Miquèl,

On 07/08/21 12:28 am, Miquel Raynal wrote:
> Hi Apurva,
> 
> Apurva Nandan <a-nandan@ti.com> wrote on Tue, 13 Jul 2021 13:05:32
> +0000:
> 
>> Enable Octal DTR SPI mode, i.e. 8D-8D-8D mode, if the SPI NAND flash
>> device supports it. Mixed OSPI (1S-1S-8S & 1S-8S-8S), mixed DTR modes
>> (1S-1D-8D), etc. aren't supported yet.
>>
>> The method to switch to Octal DTR SPI mode may vary across
>> manufacturers. For example, for Winbond, it is enabled by writing
>> values to the volatile configuration register. So, let the
>> manufacturer's code have their own implementation for switching to
>> Octal DTR SPI mode. Mixed OSPI (1S-1S-8S & 1S-8S-8S), mixed DTR modes
>> (1S-1D-8D), etc. aren't supported yet.
> 
> You can drop the final sentence which is a repetition of the previous
> paragraph.
> 

Yes right!

>> Check for the SPI NAND device's support for Octal DTR mode using
>> spinand flags, and if the op_templates allow 8D-8D-8D, call
>                                           allows
> 
>> octal_dtr_enable() manufacturer op. If the SPI controller doesn't
>> supports these modes, the selected op_templates would prevent switching
> 
>                                                    will
> 
>> to the Octal DTR mode. And finally update the spinand reg_proto
>> if success.
> 
>    on
> 

Okay, will correct all!

>>
>> Signed-off-by: Apurva Nandan <a-nandan@ti.com>
>> ---
>>   drivers/mtd/nand/spi/core.c | 46 +++++++++++++++++++++++++++++++++++++
>>   include/linux/mtd/spinand.h |  3 +++
>>   2 files changed, 49 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
>> index 1e619b6d777f..19d8affac058 100644
>> --- a/drivers/mtd/nand/spi/core.c
>> +++ b/drivers/mtd/nand/spi/core.c
>> @@ -256,6 +256,48 @@ static int spinand_init_quad_enable(struct spinand_device *spinand)
>>   			       enable ? CFG_QUAD_ENABLE : 0);
>>   }
>>   
>> +static bool spinand_op_is_octal_dtr(const struct spi_mem_op *op)
>> +{
>> +	return  op->cmd.buswidth == 8 && op->cmd.dtr &&
>> +		op->addr.buswidth == 8 && op->addr.dtr &&
>> +		op->data.buswidth == 8 && op->data.dtr;
>> +}
>> +
>> +static int spinand_init_octal_dtr_enable(struct spinand_device *spinand)
>> +{
>> +	struct device *dev = &spinand->spimem->spi->dev;
>> +	int ret;
>> +
>> +	if (!(spinand->flags & SPINAND_HAS_OCTAL_DTR_BIT))
>> +		return 0;
>> +
>> +	if (!(spinand_op_is_octal_dtr(spinand->op_templates.read_cache) &&
>> +	      spinand_op_is_octal_dtr(spinand->op_templates.write_cache) &&
>> +	      spinand_op_is_octal_dtr(spinand->op_templates.update_cache)))
>> +		return 0;
>> +
>> +	if (!spinand->manufacturer->ops->octal_dtr_enable) {
>> +		dev_err(dev,
>> +			"Missing ->octal_dtr_enable(), unable to switch mode\n");
> 
> I don't think we want an error here. Perhaps a debug or info call, but
> no more.
> 

Agree!

>> +		return -EINVAL;
>> +	}
>> +
>> +	ret = spinand->manufacturer->ops->octal_dtr_enable(spinand);
>> +	if (ret) {
>> +		dev_err(dev,
>> +			"Failed to enable Octal DTR SPI mode (err = %d)\n",
>> +			ret);
>> +		return ret;
>> +	}
>> +
>> +	spinand->reg_proto = SPINAND_OCTAL_DTR;
>> +
>> +	dev_dbg(dev,
>> +		"%s SPI NAND switched to Octal DTR SPI (8D-8D-8D) mode\n",
>> +		spinand->manufacturer->name);
>> +	return 0;
>> +}
>> +
>>   static int spinand_ecc_enable(struct spinand_device *spinand,
>>   			      bool enable)
>>   {
>> @@ -1189,6 +1231,10 @@ static int spinand_init_flash(struct spinand_device *spinand)
>>   	if (ret)
>>   		return ret;
>>   
>> +	ret = spinand_init_octal_dtr_enable(spinand);
>> +	if (ret)
>> +		return ret;
>> +
>>   	ret = spinand_upd_cfg(spinand, CFG_OTP_ENABLE, 0);
>>   	if (ret)
>>   		return ret;
>> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
>> index 35816b8cfe81..daa2ac5c3110 100644
>> --- a/include/linux/mtd/spinand.h
>> +++ b/include/linux/mtd/spinand.h
>> @@ -271,6 +271,7 @@ struct spinand_devid {
>>    * @init: initialize a SPI NAND device
>>    * @adjust_op: modify the ops for any variation in their cmd, address, dummy or
>>    *	       data phase by the manufacturer
>> + * @octal_dtr_enable: switch the SPI NAND flash into Octal DTR SPI mode
>>    * @cleanup: cleanup a SPI NAND device
>>    *
>>    * Each SPI NAND manufacturer driver should implement this interface so that
>> @@ -280,6 +281,7 @@ struct spinand_manufacturer_ops {
>>   	int (*init)(struct spinand_device *spinand);
>>   	void (*adjust_op)(struct spi_mem_op *op,
>>   			  const enum spinand_proto reg_proto);
>> +	int (*octal_dtr_enable)(struct spinand_device *spinand);
>>   	void (*cleanup)(struct spinand_device *spinand);
>>   };
>>   
>> @@ -348,6 +350,7 @@ struct spinand_ecc_info {
>>   
>>   #define SPINAND_HAS_QE_BIT		BIT(0)
>>   #define SPINAND_HAS_CR_FEAT_BIT		BIT(1)
>> +#define SPINAND_HAS_OCTAL_DTR_BIT	BIT(2)
>>   
>>   /**
>>    * struct spinand_ondie_ecc_conf - private SPI-NAND on-die ECC engine structure
> 
> 
> 
> 
> Thanks,
> Miquèl
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
> 

Thanks,
Apurva Nandan