Re: [PATCH v2 3/3] mtd: rawnand: Support for sequential cache reads

Måns Rullgård
2023-07-19T05:53:52Z

Miquel Raynal <miquel.raynal@bootlin.com> writes:

> Hi Måns,
>
> mans@mansr.com wrote on Mon, 17 Jul 2023 14:11:31 +0100:
>
>> Miquel Raynal <miquel.raynal@bootlin.com> writes:
>>
>> > So, I should have done that earlier but, could you please slow the
>> > whole operation down, just to see if there is something wrong with the
>> > timings or if we should look in another direction.
>> >
>> > Maybe you could add a boolean to flag if the last CMD was a
>> > READCACHESEQ, READCACHESTART or READCACHEEND, and if the flag is
>> > true, please get the jiffies before and after each waitrdy and
>> > delay_ns. Finally, please print the expected delay and the actual one
>> > and compare to see if something was too fast compared to what we
>> > expected.
>>
>> Between which points exactly should the delay be measured? Also, there
>> is no command called READCACHESTART. Did you mean READSTART or
>> something else?
>
> Yeah, whatever command is specific to sequential cache reads:
> https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/nand_base.c#L1218
> https://elixir.bootlin.com/linux/latest/source/drivers/mtd/nand/raw/nand_base.c#L1228

I'm still not sure what exactly you want to me measure. The waitrdy and
ndelay combined, each separately, or something else?

--
Måns Rullgård