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Re: [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to NAND flash

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On 29.11.2015 15:35, Thomas Petazzoni wrote:
> Adding Ezequiel Garcia in Cc.
>
> On Sat, 28 Nov 2015 12:14:08 +0100, Sebastian Hesselbarth wrote:
>> The NAND device found on Lenovo ix4-300d uses 4-bit BCH ECC protection.
>> Add the corresponding properties to the NAND node.
>
> If the ONFI information from the NAND flash say that it requires 4 bits
> per 512, then there should be no need to add this information to the
> Device Tree as the pxa3xx_nand driver by default uses the ONFI
> information.

Thomas,

as said in the cover letter, this is also DT cleanup with barebox
bootloader in mind. I do not accept what Linux' pxa3xx_nand driver
is doing as a reference here ;)

> Those properties are only needed when for some reason the vendor has
> chosen to use a ECC strength that doesn't match with the one advertised
> by the flash in its ONFI information (either stronger or weaker). But
> in this case, your commit log is confusing, because it says that the
> "NAND device ... uses 4-bit BCH ECC protection". If it really does,
> then the patch is not needed :-)

I agree that if ONFI is already advertising 4/512 ECC (and it is), we
do not need the properties. Anyway, IIRC barebox does not yet properly
parse ONFI or at least it does not derive minimum ECC settings from it.

I'll have to have a closer look at barebox' ONFI parsing capabilites
and can live with this patch not applied even though it does no harm.

Sebastian

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[PATCH 0/4] ARM: dt: mvebu: ix4-300d: NAND cleanup and ECC Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 12:20 +0100
  [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to NAND flash Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 12:20 +0100
    Re: [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to NAND  flash Andrew Lunn <andrew@lunn.ch> - 2015-11-28 18:10 +0100
    Re: [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to  NAND flash Thomas Petazzoni <thomas.petazzoni@free-electrons.com> - 2015-11-29 15:40 +0100
      Re: [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to NAND  flash Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-30 09:40 +0100
        Re: [PATCH 4/4] ARM: dt: mvebu: ix4-300d: Add ECC properties to NAND flash Gregory CLEMENT <gregory.clement@free-electrons.com> - 2015-11-30 15:30 +0100
  [PATCH 3/4] ARM: dt: mvebu: ix4-300d: Cleanup NAND partition ranges Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 12:20 +0100
    Re: [PATCH 3/4] ARM: dt: mvebu: ix4-300d: Cleanup NAND partition  ranges Andrew Lunn <andrew@lunn.ch> - 2015-11-28 18:10 +0100
      Re: [PATCH 3/4] ARM: dt: mvebu: ix4-300d: Cleanup NAND partition ranges Gregory CLEMENT <gregory.clement@free-electrons.com> - 2015-11-30 15:30 +0100
  [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash partition Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 12:20 +0100
    Re: [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash  partition Andrew Lunn <andrew@lunn.ch> - 2015-11-28 18:00 +0100
      Re: [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash  partition Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 18:40 +0100
        Re: [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash partition Benoit Masson <benoitm@perenite.com> - 2015-11-28 21:40 +0100
    Re: [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash  partition Andrew Lunn <andrew@lunn.ch> - 2015-11-28 22:20 +0100
      Re: [PATCH 1/4] ARM: dt: mvebu: ix4-300d: remove whole flash partition Gregory CLEMENT <gregory.clement@free-electrons.com> - 2015-11-30 15:20 +0100
  [PATCH 2/4] ARM: dt: mvebu: ix4-300d: move partitions to partition sub-node Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 12:20 +0100
    Re: [PATCH 2/4] ARM: dt: mvebu: ix4-300d: move partitions to  partition sub-node Andrew Lunn <andrew@lunn.ch> - 2015-11-28 18:10 +0100
      Re: [PATCH 2/4] ARM: dt: mvebu: ix4-300d: move partitions to  partition sub-node Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> - 2015-11-28 18:40 +0100
    Re: [PATCH 2/4] ARM: dt: mvebu: ix4-300d: move partitions to partition sub-node Gregory CLEMENT <gregory.clement@free-electrons.com> - 2015-11-30 15:20 +0100

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