Re: [RFC PATCH 2/2] mtd: spi-nor: Disable the flash quad mode in spi_nor_restore()

[Yicong Yang <yangyicong@xxxxxxxxxxxxx>]

Hi Pratyush,


On 2020/4/24 21:35, Pratyush Yadav wrote:
> Hi Yicong,
>
> On 24/04/20 05:20PM, Yicong Yang wrote:
>> If the flash's quad mode is enabled, it'll remain in the quad mode when
>> it's removed. If we drive the flash next time in SPI/Dual mode, then
>> problem occurs as the flash's quad enable bit is not cleared.
>>
>> Disable the quad mode in spi_nor_restore(), the flash will leave
>> quad mode when remove. This will make sure the flash always enter the
>> correct mode when loaded.
>>
>> Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
>> ---
>>  drivers/mtd/spi-nor/core.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>> index d0516e8..611c0b7 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -3001,6 +3001,11 @@ void spi_nor_restore(struct spi_nor *nor)
>>  	if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES) &&
>>  	    nor->flags & SNOR_F_BROKEN_RESET)
>>  		nor->params->set_4byte_addr_mode(nor, false);
>> +
>> +	/* disable quad mode */
>> +	if (spi_nor_get_protocol_width(nor->read_proto) == 4 ||
>> +	    spi_nor_get_protocol_width(nor->write_proto) == 4)
>> +		nor->params->quad_enable(nor, false);
> If a flash doesn't have a quad enable function, this will lead to a NULL 
> pointer access. Please use spi_nor_quad_enable() instead.

Okay. My careless. Thanks for pointing it out.

Thanks,
Yicong


>
>>  }
>>  EXPORT_SYMBOL_GPL(spi_nor_restore);


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