[PATCH v2 05/14] spi: spi-mem: Add debug message for spi-mem ops

[Sean Anderson]

On 2/26/21 5:12 AM, Jagan Teki wrote:
> On Fri, Feb 5, 2021 at 9:41 AM Sean Anderson <seanga2 at gmail.com> wrote:
>>
>> This prints some basic metadata about the SPI memory op. This information
>> may be used to debug SPI drivers (e.g. determining the expected SPI mode).
>> It is also helpful for verifying that the data on the wire matches the data
>> intended to be transmitted (e.g. with a logic analyzer). The opcode is
>> printed with a format of %02Xh to match the notation commonly used in flash
>> datasheets.
>>
>> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
>> Reviewed-by: Pratyush Yadav <p.yadav at ti.com>
>> ---
>>
>> Changes in v2:
>> - Add more information to exec_op debug message
>>
>>   drivers/spi/spi-mem.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index c095ae9505..6772367ef7 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -220,6 +220,13 @@ int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op)
>>          int ret;
>>          int i;
>>
>> +       dev_dbg(slave->dev,
>> +               "exec %02Xh %u-%u-%u addr=%llx dummy cycles=%u data bytes=%u\n",
>> +               op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
>> +               op->data.buswidth, op->addr.val,
>> +               op->dummy.buswidth ? op->dummy.nbytes * 8 / op->dummy.buswidth : 0,
>> +               op->data.nbytes);
> 
> This looks unnecessary to me, we have debug prints at the end of the
> function, which indeed sufficient.
> 

This is insufficient. First, that information is printed after the op
is executed. This is too late if one is trying to debug (e.g.) a hang in
the spi driver. It's also missing opcode, widths, address, and dummy
bytes. The only duplicated info here is nbytes. Since this is debugging
information, I think we should print what is most useful for people
debugging this subsystem.

--Sean