[PATCH v2 2/6] mtd: spi-nor: add erase die (chip) capability

[Tudor Ambarus]

On 11/6/23 09:34, Michael Walle wrote:
> Am 2023-11-03 14:48, schrieb Tudor Ambarus:
>> On 03.11.2023 15:37, Fabio Estevam wrote:
>>> On 03/11/2023 10:26, Tudor Ambarus wrote:
>>>
>>>> Which version of mtd-utils are you using? I guess the flash-erase
>>>
>>> mtd-utils 2.1.5
>>>
>>>> utility is written in a bad way. Please use the following while I check
>>>> what flash_erase is doing:
>>>>
>>>> time mtd_debug erase /dev/mtd0 0 134217728
>>>
>>> "mtd_debug erase" gives the same time as well:
>>>
>>> root at mcde3000a:~# time mtd_debug erase /dev/mtd0 0 134217728
>>> [ 4322.114967] spi-nor spi0.0: ***** nor->reg_proto = 0x00010101
>>> [ 4322.120861] spi-nor spi0.0: *****
>>> [ 4322.124210] spi-nor spi0.0: ***** op.cmd.nbytes = 0x01
>>> [ 4322.129478] spi-nor spi0.0: ***** op.cmd.buswidth = 0x01
>>> [ 4322.134903] spi-nor spi0.0: ***** op.cmd.opcode = 0xc4
>>> [ 4322.140154] spi-nor spi0.0: *****
>>> [ 4322.143491] spi-nor spi0.0: ***** op.addr.nbytes = 0x04
>>> [ 4322.148831] spi-nor spi0.0: ***** op.addr.buswidth = 0x01
>>> [ 4322.154341] spi-nor spi0.0: ***** op.addr.buswidth = 0x0
>>> [ 4322.159761] spi-nor spi0.0: *****
>>> [ 4322.163098] spi-nor spi0.0: ***** op.dummy.nbytes = 0x00
>>> [ 4322.168524] spi-nor spi0.0: ***** op.dummy.buswidth = 0x00
>>> [ 4322.174118] spi-nor spi0.0: *****
>>> [ 4322.177439] spi-nor spi0.0: ***** op.data.buswidth = 0x00
>>> [ 4322.182948] spi-nor spi0.0: ***** op.data.nbytes = 0
>>> [ 4439.966060] spi-nor spi0.0: ***** nor->reg_proto = 0x00010101
>>> [ 4439.971920] spi-nor spi0.0: *****
>>> [ 4439.975252] spi-nor spi0.0: ***** op.cmd.nbytes = 0x01
>>> [ 4439.980511] spi-nor spi0.0: ***** op.cmd.buswidth = 0x01
>>> [ 4439.985928] spi-nor spi0.0: ***** op.cmd.opcode = 0xc4
>>> [ 4439.991174] spi-nor spi0.0: *****
>>> [ 4439.994504] spi-nor spi0.0: ***** op.addr.nbytes = 0x04
>>> [ 4439.999834] spi-nor spi0.0: ***** op.addr.buswidth = 0x01
>>> [ 4440.005335] spi-nor spi0.0: ***** op.addr.buswidth = 0x4000000
>>> [ 4440.011272] spi-nor spi0.0: *****
>>> [ 4440.014604] spi-nor spi0.0: ***** op.dummy.nbytes = 0x00
>>> [ 4440.020018] spi-nor spi0.0: ***** op.dummy.buswidth = 0x00
>>> [ 4440.025606] spi-nor spi0.0: *****
>>> [ 4440.028937] spi-nor spi0.0: ***** op.data.buswidth = 0x00
>>> [ 4440.034438] spi-nor spi0.0: ***** op.data.nbytes = 0
>>> Erased 134217728 bytes from address 0x00000000 in flash
>>>
>>> real    3m57.384s
>>> user    0m0.005s
>>> sys    3m35.211s
>>>
>>
>> Yep, it's strange, we'll have to check what's happening. I found my
>> n25q00 flash, on my side all its 4 dice are erased in 5 sec.  SFDP
>> defines how long the erase die should take, see BFPT dword 11. You can
>> start with that.
> 
> Had the flash some contents or was it all-ff? Maybe the Micron flash will
> check if all bytes are one and will skip the erase.

it had some contents, but not different than 0xff
> 
> Die/Chip erases will take much longer most of the time and are comparable
> to individual sector erases (as Fabio also found out). You'll probably
> just save the overhead of the indivudal commands.

There is a speed benefit in using die erase instead of individual sector
erases.
> 
> I've looked at the N25Q00AA datasheet and the erase time there is 153s
> (typ) for *one* die.
> 

you mean mt25q. Table 49 in
https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_01g_bbb_0.pdf


Each die has 64MB. A die is composed of either 16384 4KB sectors or 2048
sectors of 32KB.

4KB typical erase time is 0.05s, thus a die will be erased in 819.2s.
32KB typical erase time is 0.1s, thus a die will be erased in 204.8s.
die erase typical erase time is 153s.

4K max erase time is 0.4s, thus a die will be erased in 6553.6s
32KB max erase time is 1, thus a die will be erased in 2048s.
die erase max time is 460s.

so you might say that 32KB typical erase time might be comparable to a
die erase command when erasing an entire die with 32KB erases, but even
so, it should be preferable to use die erase cmd. Instead of sending a
write enable followed by a sector erase command for each sector, you
could instead use a single write enable followed by a single die erase
command.

ta