Most SPI flash do support various "sector" sizes, 4kB is sometimes called
subsector. OpenOCD uses for bigger flash always the largest available size:
Erasing a substancial part by subsector erase is usually *much* slower than by
the larger sectors. E.g. for MT25QL512ABB: subsector 4kByte typ. 50ms, 64kByte
typ. 150ms, so roughly factor 5. If you can't live with the larger sector size,
these alternatives came to my mind:
1) *Add* corresponding subsector size/erase command to spi.c for *all* devices
where applicable and a a suitable subsector erase command to the various flash
drivers. Note that the "auto erase" option would still use the "old" erase
command if you don't add a suitable strategy there.
2)* Change* all sector erase commands and sector sizes in spi.c to the
appropriate subsector variants. But be prepared for some polite complaints that
programming time increased by a factor of four ...
3) Add a special command to send arbitrary command bytes to the flash, see e.g.
"stmqspi cmd" in the stmqspi flash driver or a command to override the flash
parameters in spi.c like "stmqspi set" ibid. That might be useful for other
purposes as well.
---
**[tickets:#437] Wrong sector size for w25q16jv / RP2040 pico**
**Status:** new
**Milestone:** 0.11.0
**Created:** Sun Sep 29, 2024 05:57 AM UTC by JustAnother1
**Last Updated:** Sun Sep 29, 2024 05:57 AM UTC
**Owner:** nobody
in line 305 of src/flash/nor/rp2040.c (current git) there is this comment:
~~~
/*
The RP2040 Boot ROM provides a _flash_range_erase() API call documented
in Section 2.8.3.1.3:
https://datasheets.raspberrypi.org/rp2040/rp2040-datasheet.pdf
and the particular source code for said Boot ROM function can be found
here:
https://github.com/raspberrypi/pico-bootrom/blob/master/bootrom/program_flash_generic.c
In theory, the function algorithm provides for erasing both a smaller
"sector" (4096 bytes) and
an optional larger "block" (size and command provided in args).
*/
~~~
I have verified the erase function from the boot rom of the RP2040. That is the
same function openocd uses here. And I found that it is able to erase a 4096
byte sector. So the comment is right.
I wrote something before and after and in a sector and then called
_flash_range_erase() from the boot-rom to erase the one 4096 bytes sized sector
and only the bytes in the sector have been erased. The data before and after
were still there. So erasing 4096 bytes is not theory anymore.
I therefore think that line 55 in src/flash/nor/rp2040.c and line 123 (129?)
in src/flash/nor/spi.c should be changed. They specify the sector size to
0x10000 (64k) and should be 1000(4k)
What else can I do to get this change merged, or is there a reason not to do
this?
---
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