[BUG] pxa3xx: wait time out when scanning for bb

[Ezequiel Garcia]

On 28 November 2017 at 10:30, Miquel RAYNAL
<miquel.raynal at free-electrons.com> wrote:
> Hi Sean,
>
>
>> > Also, what kernel are you using ?
>> 4.14.0 :-)
>
> Good !
>
>> [    2.288684] pxa3xx-nand f10d0000.flash: This platform can't do DMA
>> on this device
>
> FYI, this is normal, the NAND controller does not have any DMA feature
> on Armada 38x (NFCv2).
>
>> [    2.296924] nand: device found, Manufacturer ID: 0x2c, Chip ID:
>> 0xda [    2.303311] nand: Micron MT29F2G08ABAEAH4
>> [    2.307334] nand: 256 MiB, SLC, erase size: 128 KiB, page size:
>> 2048, OOB size: 64
>> [    2.314939] pxa3xx-nand f10d0000.flash: ECC strength 16, ECC step
>> size 2048
>
> In theory, Marvell NAND flash controller does support 16-bit strength
> per 512 bytes over 2048 bytes pages. However, this controller driver
> (pxa3xx_nand) does not. See [1] for the supported configurations.
>

Why do you say the driver does not support it?

It's automatically selecting this:

        /*
         * Required ECC: 4-bit correction per 512 bytes
         * Select: 16-bit correction per 2048 bytes
         */
        } else if (strength == 4 && ecc_stepsize == 512 && page_size == 2048) {
                info->ecc_bch = 1;
                info->chunk_size = 2048;
                info->spare_size = 32;
                info->ecc_size = 32;
                ecc->mode = NAND_ECC_HW;
                ecc->size = info->chunk_size;
                ecc->layout = &ecc_layout_2KB_bch4bit;
                ecc->strength = 16;

Otherwise, you would have seen the "ECC strength ... at page size ...
is not supported"

> The ECC strength shown here is probably the best to use with this type
> of NAND device but I suggest you try with 4b/512B by using these two
> properties like in [2]:
>
>         nand-ecc-strength = <4>;
>         nand-ecc-step-size = <512>;
>
>
> Thanks,
> Miquèl
>
> [1]
> http://elixir.free-electrons.com/linux/v4.14/source/drivers/mtd/nand/pxa3xx_nand.c#L1575
>
> [2]
> http://elixir.free-electrons.com/linux/v4.14/source/arch/arm/boot/dts/armada-385-db-ap.dts#L172
>
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-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar