Re: [PATCH v2] mtd: spi-nor: use spi-mem dirmap API

[Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>]

Hello!

On 11/09/2019 10:35 PM, Boris Brezillon wrote:

>> Make use of the spi-mem direct mapping API to let advanced controllers
>> optimize read/write operations when they support direct mapping.
>>
>> Based on the original patch by Boris Brezillon <boris.brezillon@xxxxxxxxxxx>.
>>
>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
>>
>> ---
>> Changes in version 2:
>> - moved the spi_mem_dirmap_{read|write}() calls from spi_nor_{read|write}() to
>>   spi_nor_spimem_{read|write}_data().
>>
>>  drivers/mtd/spi-nor/spi-nor.c |  125 +++++++++++++++++++++++++++++++++---------
>>  include/linux/mtd/spi-nor.h   |    5 +
>>  2 files changed, 104 insertions(+), 26 deletions(-)
>>
>> Index: linux/drivers/mtd/spi-nor/spi-nor.c
>> ===================================================================
>> --- linux.orig/drivers/mtd/spi-nor/spi-nor.c
>> +++ linux/drivers/mtd/spi-nor/spi-nor.c
>> @@ -305,22 +305,28 @@ static ssize_t spi_nor_spimem_xfer_data(
>>  static ssize_t spi_nor_spimem_read_data(struct spi_nor *nor, loff_t from,
>>  					size_t len, u8 *buf)
>>  {
>> -	struct spi_mem_op op =
>> -		SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 1),
>> -			   SPI_MEM_OP_ADDR(nor->addr_width, from, 1),
>> -			   SPI_MEM_OP_DUMMY(nor->read_dummy, 1),
>> -			   SPI_MEM_OP_DATA_IN(len, buf, 1));
>> -
>> -	/* get transfer protocols. */
>> -	op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->read_proto);
>> -	op.addr.buswidth = spi_nor_get_protocol_addr_nbits(nor->read_proto);
>> -	op.dummy.buswidth = op.addr.buswidth;
>> -	op.data.buswidth = spi_nor_get_protocol_data_nbits(nor->read_proto);
>> +	if (!nor->dirmap.rdesc) {
>> +		struct spi_mem_op op =
>> +			SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 1),
>> +				   SPI_MEM_OP_ADDR(nor->addr_width, from, 1),
>> +				   SPI_MEM_OP_DUMMY(nor->read_dummy, 1),
>> +				   SPI_MEM_OP_DATA_IN(len, buf, 1));
>> +
>> +		/* get transfer protocols. */
>> +		op.cmd.buswidth =
>> +			spi_nor_get_protocol_inst_nbits(nor->read_proto);
>> +		op.addr.buswidth =
>> +			spi_nor_get_protocol_addr_nbits(nor->read_proto);
>> +		op.dummy.buswidth = op.addr.buswidth;
>> +		op.data.buswidth =
>> +			spi_nor_get_protocol_data_nbits(nor->read_proto);
>>  
>> -	/* convert the dummy cycles to the number of bytes */
>> -	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
>> +		/* convert the dummy cycles to the number of bytes */
>> +		op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
>>  
>> -	return spi_nor_spimem_xfer_data(nor, &op);
>> +		return spi_nor_spimem_xfer_data(nor, &op);
>> +	}
>> +	return spi_mem_dirmap_read(nor->dirmap.rdesc, from, len, buf);
> 
> Can we put the spi_mem_dirmap_read() in the if() branch instead of
> having an extra level of indentation for the most complex block.

   Have you noticed a complex variable initializer in that block? Do you want
it to be done on the simple branch as well? 

> 	if (nor->dirmap.rdesc)
> 		return spi_mem_dirmap_read(nor->dirmap.rdesc, from,
> 					   len, buf);
> 
> 	...
> 
> (same comment applies to the write path BTW).
> 
> With this addressed, you can add
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

   Thank you. :-)

> 
> Thanks,
> 
> Boris

MBR, Sergei

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