UBI on SPI NOR flash

[Jan Lübbe]

Hi!

On Fri, 2012-08-24 at 15:31 +0300, Artem Bityutskiy wrote:
> On Wed, 2012-08-15 at 19:10 +0200, Jan Lübbe wrote:
> > Hi all!
> > 
> > I'm trying to use UBIFS on SPI NOR flash, but have been unable to get it
> > to work on kernel version 3.5. It is a Numonyx N25Q128 connected to an
> > TI AM3505.
> 
> First of all, run the mtd tests and see if the flash works well.

~ # modprobe mtd_readtest dev=5
[  124.351074] 
[  124.353057] =================================================
[  124.359466] mtd_readtest: MTD device: 5
[  124.365173] mtd_readtest: not NAND flash, assume page size is 512 bytes.
[  124.373107] mtd_readtest: MTD device size 3670016, eraseblock size 65536, page size 512, count of eraseblocks 56, pages per eraseblock 128, OOB size 0
[  124.388000] mtd_readtest: testing page read
[  126.754089] mtd_readtest: finished
[  126.757690] =================================================
~ # modprobe mtd_speedtest dev=5
[  160.338775] 
[  160.344146] =================================================
[  160.350708] mtd_speedtest: MTD device: 5
[  160.354827] mtd_speedtest: not NAND flash, assume page size is 512 bytes.
[  160.362396] mtd_speedtest: MTD device size 3670016, eraseblock size 65536, page size 512, count of eraseblocks 56, pages per eraseblock 128, OOB size 0
[  204.830078] mtd_speedtest: testing eraseblock write speed
[  218.410614] mtd_speedtest: eraseblock write speed is 264 KiB/s
[  218.416717] mtd_speedtest: testing eraseblock read speed
[  220.146087] mtd_speedtest: eraseblock read speed is 2078 KiB/s
[  264.651000] mtd_speedtest: testing page write speed
[  278.239562] mtd_speedtest: page write speed is 263 KiB/s
[  278.245697] mtd_speedtest: testing page read speed
[  280.607025] mtd_speedtest: page read speed is 1521 KiB/s
[  324.869445] mtd_speedtest: testing 2 page write speed
[  338.450592] mtd_speedtest: 2 page write speed is 263 KiB/s
[  338.456359] mtd_speedtest: testing 2 page read speed
[  340.498870] mtd_speedtest: 2 page read speed is 1760 KiB/s
[  340.505065] mtd_speedtest: Testing erase speed
[  384.802856] mtd_speedtest: erase speed is 80 KiB/s
[  384.807922] mtd_speedtest: Testing 2x multi-block erase speed
[  430.186370] mtd_speedtest: 2x multi-block erase speed is 78 KiB/s
[  430.193389] mtd_speedtest: Testing 4x multi-block erase speed
[  475.582244] mtd_speedtest: 4x multi-block erase speed is 78 KiB/s
[  475.588653] mtd_speedtest: Testing 8x multi-block erase speed
[  521.005981] mtd_speedtest: 8x multi-block erase speed is 78 KiB/s
[  521.013031] mtd_speedtest: Testing 16x multi-block erase speed
[  566.628875] mtd_speedtest: 16x multi-block erase speed is 78 KiB/s
[  566.636016] mtd_speedtest: Testing 32x multi-block erase speed
[  611.978057] mtd_speedtest: 32x multi-block erase speed is 79 KiB/s
[  611.985198] mtd_speedtest: Testing 64x multi-block erase speed
[  657.134216] mtd_speedtest: 64x multi-block erase speed is 79 KiB/s
[  657.141326] mtd_speedtest: finished
[  657.144989] =================================================
~ # modprobe mtd_stresstest dev=5 count=100
[  708.805480] 
[  708.807464] =================================================
[  708.815093] mtd_stresstest: MTD device: 5
[  708.819763] mtd_stresstest: not NAND flash, assume page size is 512 bytes.
[  708.827911] mtd_stresstest: MTD device size 3670016, eraseblock size 65536, page size 512, count of eraseblocks 56, pages per eraseblock 128, OOB size 0
[  708.848632] mtd_stresstest: doing operations
[  708.853637] mtd_stresstest: 0 operations done
[  775.528625] mtd_stresstest: finished, 100 operations done
[  775.535125] =================================================

> Another problem I know with SPI flashes is that UBIFS uses vmalloc'd
> memory for I/O, which is not suitable for DMA-ing on ARM platforms and
> may cause subtle bugs and curruptions. Can you try to disable DMA and
> see if the issues go away?

It works if I disable DMA in drivers/spi/spi-omap2-mcspi.c (simply
comment out the DMA branch in omap2_mcspi_work). I can use UBI&UBIFS
without problems for far. When rebooting to a kernel with DMA enabled I
can no longer attach the previously working volume. Moving back to the
PIO-Kernel, it works again.

Where should this be fixed? Should UBI use kmalloc'ed memory?

Why does this work for NAND controllers using DMA? :)

Regards,
Jan
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