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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 12/13] mtd: spinand: Perform Power-on-Reset when runtime_pm suspend is issued
Date: Fri, 20 Aug 2021 17:15:38 +0530	[thread overview]
Message-ID: <2437d7b9-2a01-28c7-9a81-f38c35f37964@ti.com> (raw)
In-Reply-To: <20210806211231.5c569939@xps13>



On 07/08/21 12:42 am, Miquel Raynal wrote:
> Hi Apurva,
> 
> Apurva Nandan <a-nandan@ti.com> wrote on Tue, 13 Jul 2021 13:05:37
> +0000:
> 
>> A soft reset using FFh command doesn't erase the flash's configuration
>> and doesn't reset the SPI IO mode also. This can result in the flash
>> being in a different SPI IO mode, e.g. Octal DTR, when resuming from
>> sleep. This would render the flash in an unusable state.
> 
>                could put the falsh in?
> 

Okay, will make it clearer.
Basically, we don't want the flash to be in an ambiguous state. It might 
or might not have undergone a power off during the suspend state. So, 
the spinand core wouldn't know if the flash is still in Octal DTR mode 
or not. If it is still in Octal DTR mode, then none of the SPI 
instruction during mtd_resume() would work. So this is an ambiguous 
situation for driver. To avoid this, perform a PoR reset before suspending.

>> Perform a Power-on-Reset (PoR), if available in the flash, when
>> suspending the device by runtime_pm. This would set the flash to clean
> 
> I think runtime_pm is something else.
> 

Yeah, will make it clearer.

>> state for reinitialization during resume and would also ensure that it
>> is in standard SPI IO mode (1S-1S-1S) before the resume begins.
> 
> Please add a comment about this to explain why we don't do this reset
> at resume time.
> 

Yes sure!

>>
>> Signed-off-by: Apurva Nandan <a-nandan@ti.com>
>> ---
>>   drivers/mtd/nand/spi/core.c | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
>> index 608f4eb85b0a..6fb3aa6af540 100644
>> --- a/drivers/mtd/nand/spi/core.c
>> +++ b/drivers/mtd/nand/spi/core.c
>> @@ -1329,6 +1329,21 @@ static void spinand_mtd_resume(struct mtd_info *mtd)
>>   	spinand_ecc_enable(spinand, false);
>>   }
>>   
>> +static int spinand_mtd_suspend(struct mtd_info *mtd)
>> +{
>> +	struct spinand_device *spinand = mtd_to_spinand(mtd);
>> +	int ret;
>> +
>> +	if (!(spinand->flags & SPINAND_HAS_POR_CMD_BIT))
>> +		return 0;
>> +
>> +	ret = spinand_power_on_rst_op(spinand);
>> +	if (ret)
>> +		dev_err(&spinand->spimem->spi->dev, "suspend() failed\n");
>> +
>> +	return ret;
>> +}
>> +
>>   static int spinand_init(struct spinand_device *spinand)
>>   {
>>   	struct device *dev = &spinand->spimem->spi->dev;
>> @@ -1401,6 +1416,7 @@ static int spinand_init(struct spinand_device *spinand)
>>   	mtd->_erase = spinand_mtd_erase;
>>   	mtd->_max_bad_blocks = nanddev_mtd_max_bad_blocks;
>>   	mtd->_resume = spinand_mtd_resume;
>> +	mtd->_suspend = spinand_mtd_suspend;
>>   
>>   	if (nand->ecc.engine) {
>>   		ret = mtd_ooblayout_count_freebytes(mtd);
> 
> 
> Thanks,
> Miquèl
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
> 

Thanks,
Apurva Nandan

  reply	other threads:[~2021-08-20 11:46 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-13 13:05 [PATCH 00/13] mtd: spinand: Add Octal DTR SPI (8D-8D-8D) mode support Apurva Nandan
2021-07-13 13:05 ` [PATCH 01/13] spi: spi-mem: Add DTR templates for cmd, address, dummy and data phase Apurva Nandan
2021-07-14 17:06   ` Mark Brown
2021-08-23  7:57   ` Boris Brezillon
2021-07-13 13:05 ` [PATCH 02/13] mtd: spinand: Add enum spinand_proto to indicate current SPI IO mode Apurva Nandan
2021-07-13 13:05 ` [PATCH 03/13] mtd: spinand: Setup spi_mem_op for the SPI IO protocol using reg_proto Apurva Nandan
2021-08-06 18:30   ` Miquel Raynal
2021-08-20  9:52     ` Apurva Nandan
2021-08-20 12:08       ` Miquel Raynal
2021-08-23  7:11         ` Boris Brezillon
2021-08-23  7:24           ` Miquel Raynal
2021-07-13 13:05 ` [PATCH 04/13] mtd: spinand: Fix odd byte addr and data phase in read/write reg op and write VCR op for Octal DTR mode Apurva Nandan
2021-08-06 18:43   ` Miquel Raynal
2021-08-20 10:27     ` Apurva Nandan
2021-08-20 12:06       ` Miquel Raynal
2021-07-13 13:05 ` [PATCH 05/13] mtd: spinand: Add adjust_op() in manufacturer_ops to modify the ops for manufacturer specific changes Apurva Nandan
2021-07-13 13:05 ` [PATCH 06/13] mtd: spinand: Add macros for Octal DTR page read and write operations Apurva Nandan
2021-08-06 18:54   ` Miquel Raynal
2021-08-20 10:35     ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 07/13] mtd: spinand: Allow enabling Octal DTR mode in the core Apurva Nandan
2021-08-06 18:58   ` Miquel Raynal
2021-08-20 10:41     ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 08/13] mtd: spinand: Reject 8D-8D-8D op_templates if octal_dtr_enale() is missing in manufacturer_op Apurva Nandan
2021-08-06 19:01   ` Miquel Raynal
2021-08-20 11:26     ` Apurva Nandan
2021-08-20 12:14       ` Miquel Raynal
2021-08-20 13:54         ` Apurva Nandan
2021-08-20 14:38           ` Miquel Raynal
2021-08-20 15:53             ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 09/13] mtd: spinand: Add support for write volatile configuration register op Apurva Nandan
2021-08-06 19:05   ` Miquel Raynal
2021-08-20 11:30     ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 10/13] mtd: spinand: Add octal_dtr_enable() for Winbond manufacturer_ops Apurva Nandan
2021-08-06 19:06   ` Miquel Raynal
2021-08-20 11:31     ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 11/13] mtd: spinand: Add support for Power-on-Reset (PoR) instruction Apurva Nandan
2021-08-06 19:08   ` Miquel Raynal
2021-08-20 11:39     ` Apurva Nandan
2021-08-20 12:18       ` Miquel Raynal
2021-08-20 13:41         ` Apurva Nandan
2021-08-20 14:17           ` Miquel Raynal
2021-08-20 15:56             ` Apurva Nandan
2021-07-13 13:05 ` [PATCH 12/13] mtd: spinand: Perform Power-on-Reset when runtime_pm suspend is issued Apurva Nandan
2021-08-06 19:12   ` Miquel Raynal
2021-08-20 11:45     ` Apurva Nandan [this message]
2021-07-13 13:05 ` [PATCH 13/13] mtd: spinand: Add support for Winbond W35N01JW SPI NAND flash Apurva Nandan
2021-08-06 19:14   ` Miquel Raynal
2021-08-20 11:51     ` Apurva Nandan
2021-08-20 12:02       ` Miquel Raynal
2021-08-20 13:14         ` Apurva Nandan
2021-07-20 16:53 ` [PATCH 00/13] mtd: spinand: Add Octal DTR SPI (8D-8D-8D) mode support Nandan, Apurva

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