Re: [PATCH 1/3] mtd: spi-nor: sst: fix write support for SST_WRITE marked devices

Tudor.Ambarus
2020-09-16T09:36:34Z

On 9/14/20 3:00 PM, Vignesh Raghavendra wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> On 9/11/20 8:17 PM, Marco Felsch wrote:
>> The sst write support for devices using the special SST_WRITE routine
>> is broken since commit commit df5c21002cf4 ("mtd: spi-nor: use spi-mem
>> dirmap API") because the spi_nor_create_write_dirmap() function checks
>> SPINOR_OP_AAI_WP and sst_write_second. These checks are not valid during
>> probe. The check seems also to be broken since the "op->addr.nbytes = 0"
>> causes the devm_spi_mem_dirmap_create() function to return
>> PTR_ERR(-EINVAL) and the probe() function will fail.
>>
>> It seems that the commit only copy'n'pasted the existing logic. Use the
>> correct SST_WRITE flag and return 0 to fix both issues.
>>
>> Fixes: df5c21002cf4 ("mtd: spi-nor: use spi-mem dirmap API")
>> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
>> ---
>> drivers/mtd/spi-nor/core.c | 12 +++++++++---
>> 1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
>> index 65eff4ce6ab1..31869ac245a8 100644
>> --- a/drivers/mtd/spi-nor/core.c
>> +++ b/drivers/mtd/spi-nor/core.c
>> @@ -3289,15 +3289,21 @@ static int spi_nor_create_write_dirmap(struct spi_nor *nor)
>> };
>> struct spi_mem_op *op = &info.op_tmpl;
>>
>> + /*
>> + * Most SST SPI-NOR's have a special write routine.which should so
>
> s/SPI-NOR/SPI NOR.
>
>> + * dirmap.wdesc is not supported for these.
>
> Or How about more readable version:
>
> "Most SST flashes have special sequence for writing data to the flash
> and therefore cannot support writes through direct mapping APIs."
>
>> + */
>> + if (nor->info->flags & SST_WRITE) {
>> + nor->dirmap.wdesc = NULL;
>
> nor->dirmap.wdesc is known to be NULL at this point. So no need to set
> to NULL again.
>
>> + return 0;
>> + }
>> +
>> /* get transfer protocols. */
>> op->cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->write_proto);
>> op->addr.buswidth = spi_nor_get_protocol_addr_nbits(nor->write_proto);
>> op->dummy.buswidth = op->addr.buswidth;
>> op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->write_proto);
>>
>> - if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
>> - op->addr.nbytes = 0;
>> -
>> nor->dirmap.wdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
>> &info);
>> return PTR_ERR_OR_ZERO(nor->dirmap.wdesc);
>>

With Vignesh's comments addressed, one can add:
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>