[PATCH v3 2/2] mtd: spi-nor: micron-st: Add support for mt25qu01g

[Fabio Estevam]

Hi Tudor,

On Fri, Oct 27, 2023 at 3:59 AM Tudor Ambarus <tudor.ambarus at linaro.org> wrote:

> Would you please do the following tests instead?

Ok, I am back to using v2:

+++ b/drivers/mtd/spi-nor/micron-st.c
@@ -429,6 +429,11 @@ static const struct flash_info st_nor_parts[] = {
                         SPI_NOR_BP3_SR_BIT6,
                .no_sfdp_flags = SECT_4K | SPI_NOR_QUAD_READ,
                .mfr_flags = USE_FSR,
+       }, {
+               .id = SNOR_ID(0x20, 0xbb, 0x21, 0x10, 0x44, 0x00),
+               .name = "mt25qu01g",
+               .flags = NO_CHIP_ERASE,
+               .mfr_flags = USE_FSR,
        }, {

Here are the results:

1)
~# dd if=/dev/urandom of=spi_test bs=1M count=128
128+0 records in
128+0 records out

2)
~# time mtd_debug write /dev/mtd0 0 134217728 spi_test
Copied 134217728 bytes from spi_test to address 0x00000000 in flash

real 2m21.889s
user 0m0.001s
sys 1m14.607s

3)
~# mtd_debug read /dev/mtd0 0 256 first-die
Copied 256 bytes from address 0x00000000 in flash to first-die

~# hexdump first-die
0000000 8090 0008 4d0d d780 0a18 422d 002c c182
0000010 2d54 0248 0119 0680 11cc 8080 301e 0401
.....[snip]
00000f0 0010 4480 2800 4208 a830 6451 0882 4088
0000100
~# mtd_debug read /dev/mtd0 67108864 256 second-die
Copied 256 bytes from address 0x04000000 in flash to second-die
~# hexdump second-die
0000000 1080 ca40 0890 2000 880d 00c0 0142 8440
0000010 1081 6908 0804 0120 82b8 40a4 9440 0290
....[snip]
00000f0 c116 1630 221c 4222 0080 0271 4141 a00c
0000100

4)
~# time flash_erase /dev/mtd0 0 0
Erasing 131072 Kibyte @ 0 -- 100 % complete

real 4m5.447s
user 0m0.001s
sys 3m42.945s
~# hexdump -C /dev/mtd0
00000000  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |................|
*
08000000

5)
~# time mtd_debug write /dev/mtd0 0 134217728 spi_test
Copied 134217728 bytes from spi_test to address 0x00000000 in flash

real 2m7.288s
user 0m0.005s
sys 1m52.549s
~# time mtd_debug read /dev/mtd0 0 134217728 spi_read
Copied 134217728 bytes from address 0x00000000 in flash to spi_read

real 0m5.372s
user 0m0.000s
sys 0m3.524s
~# sha1sum spi_test spi_read
3dd58f6d935db05a37d597d25562cfa107c3cf7f  spi_test
3dd58f6d935db05a37d597d25562cfa107c3cf7f  spi_read

Please note the very long time it takes to complete the full write and
erase commands in steps 4) and 5).

> Not a good idea to remove USE_FSR. FSR is used to determine page program
> and erase errors, please keep it.

Ok, I will keep it.

> I wonder why this is needed if it's not used anywhere. Do you set this
> just so that based on it to set the no-chip-erase flag? If yes, set the

Yes, correct. I did it as per Michael's suggestion. I will keep the
no-chip-erase flag.

> no chip erase flag directly and drop the entire fixup hook. Would be
> good to introduce the die erase capability if you care about erase speed.

Yes, the erase speed is bad.

Any suggestions as to how to introduce the die-erase capability?

> Skimming over the datasheet you pointed out didn't help me remove my
> concerns.
> See "Table 24: 4-BYTE READ MEMORY Operations", it says "a die can be
> read with a single command", but we don't consider this anywhere in the
> code.
>
> If the flash works with the current code, why does it work?
> Please enable dev_dbg, we have one in spi_nor_read(), we shall see
> what's going on.

Here is the 'mtd_debug read' result with dev_dbg() enabled:

~# time mtd_debug read /dev/mtd0 0 134217728 spi_read
[  174.405423] spi-nor spi0.0: from 0x00000000, len 4194304
[  174.499346] spi-nor spi0.0: from 0x00400000, len 4194304
[  174.592396] spi-nor spi0.0: from 0x00800000, len 4194304
[  174.685531] spi-nor spi0.0: from 0x00c00000, len 4194304
[  174.778882] spi-nor spi0.0: from 0x01000000, len 4194304
[  174.871549] spi-nor spi0.0: from 0x01400000, len 4194304
[  174.964846] spi-nor spi0.0: from 0x01800000, len 4194304
[  175.057758] spi-nor spi0.0: from 0x01c00000, len 4194304
[  175.151109] spi-nor spi0.0: from 0x02000000, len 4194304
[  175.244185] spi-nor spi0.0: from 0x02400000, len 4194304
[  175.337410] spi-nor spi0.0: from 0x02800000, len 4194304
[  175.430272] spi-nor spi0.0: from 0x02c00000, len 4194304
[  175.523659] spi-nor spi0.0: from 0x03000000, len 4194304
[  175.616721] spi-nor spi0.0: from 0x03400000, len 4194304
[  175.710109] spi-nor spi0.0: from 0x03800000, len 4194304
[  175.803029] spi-nor spi0.0: from 0x03c00000, len 4194304
[  175.896167] spi-nor spi0.0: from 0x04000000, len 4194304
[  175.989247] spi-nor spi0.0: from 0x04400000, len 4194304
[  176.082623] spi-nor spi0.0: from 0x04800000, len 4194304
[  176.175383] spi-nor spi0.0: from 0x04c00000, len 4194304
[  176.268842] spi-nor spi0.0: from 0x05000000, len 4194304
[  176.361777] spi-nor spi0.0: from 0x05400000, len 4194304
[  176.455055] spi-nor spi0.0: from 0x05800000, len 4194304
[  176.548084] spi-nor spi0.0: from 0x05c00000, len 4194304
[  176.641573] spi-nor spi0.0: from 0x06000000, len 4194304
[  176.734721] spi-nor spi0.0: from 0x06400000, len 4194304
[  176.827902] spi-nor spi0.0: from 0x06800000, len 4194304
[  176.920998] spi-nor spi0.0: from 0x06c00000, len 4194304
[  177.014415] spi-nor spi0.0: from 0x07000000, len 4194304
[  177.107817] spi-nor spi0.0: from 0x07400000, len 4194304
[  177.201154] spi-nor spi0.0: from 0x07800000, len 4194304
[  177.294104] spi-nor spi0.0: from 0x07c00000, len 4194304
Copied 134217728 bytes from address 0x00000000 in flash to spi_read

real 0m5.525s
user 0m0.001s
sys 0m3.687s

Thanks