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Subject: Re: 32-bit Amlogic (ARM) SoC: kernel BUG in kfree()
To:     Martin Blumenstingl <martin.blumenstingl@googlemail.com>
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From:   Liang Yang <liang.yang@amlogic.com>
Message-ID: <45ce172c-5c76-bb69-31c8-af91e8ffdd68@amlogic.com>
Date:   Thu, 11 Apr 2019 11:00:31 +0800
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Hi Martin,
On 2019/4/11 1:54, Martin Blumenstingl wrote:
> Hi Liang,
> 
> On Wed, Apr 10, 2019 at 1:08 PM Liang Yang <liang.yang@amlogic.com> wrote:
>>
>> Hi Martin,
>>
>> On 2019/4/5 12:30, Martin Blumenstingl wrote:
>>> Hi Liang,
>>>
>>> On Fri, Mar 29, 2019 at 8:44 AM Liang Yang <liang.yang@amlogic.com> wrote:
>>>>
>>>> Hi Martin,
>>>>
>>>> On 2019/3/29 2:03, Martin Blumenstingl wrote:
>>>>> Hi Liang,
>>>> [......]
>>>>>> I don't think it is caused by a different NAND type, but i have followed
>>>>>> the some test on my GXL platform. we can see the result from the
>>>>>> attachment. By the way, i don't find any information about this on meson
>>>>>> NFC datasheet, so i will ask our VLSI.
>>>>>> Martin, May you reproduce it with the new patch on meson8b platform ? I
>>>>>> need a more clear and easier compared log like gxl.txt. Thanks.
>>>>> your gxl.txt is great, finally I can also compare my own results with
>>>>> something that works for you!
>>>>> in my results (see attachment) the "DATA_IN  [256 B, force 8-bit]"
>>>>> instructions result in a different info buffer output.
>>>>> does this make any sense to you?
>>>>>
>>>> I have asked our VLSI designer for explanation or simulation result by
>>>> an e-mail. Thanks.
>>> do you have any update on this?
>> Sorry. I haven't got reply from VLSI designer yet. We tried to improve
>> priority yesterday, but i still can't estimate the time. There is no
>> document or change list showing the difference between m8/b and gxl/axg
>> serial chips. Now it seems that we can't use command NFC_CMD_N2M on nand
>> initialization for m8/b chips and use *read byte from NFC fifo register*
>> instead.
> thank you for the status update!
> 
> I am trying to understand your suggestion not to use NFC_CMD_N2M:
> the documentation (public S922X datasheet from Hardkernel: [0]) states
> that P_NAND_BUF (NFC_REG_BUF in the meson_nand driver) can hold up to
> four bytes of data. is this the "read byte from NFC FIFO register" you
> mentioned?
> 
You are right.take the early meson NFC driver V2 on previous mail as a 
reference.

> Before I spend time changing the code to use the FIFO register I would
> like to wait for an answer from your VLSI designer.
> Setting the "correct" info buffer length for NFC_CMD_N2M on the 32-bit
> SoCs seems like an easier solution compared to switching to the FIFO
> register. Keeping NFC_CMD_N2M on the 32-bit SoCs also allows us to
> have only one code-path for 32 and 64 bit SoCs, meaning we don't have
> to maintain two separate code-paths for basically the same
> functionality (assuming that NFC_CMD_N2M is not completely broken on
> the 32-bit SoCs, we just don't know how to use it yet).
> 
All right. I am also waiting for the answer.
> 
> Regards
> Martin
> 
> 
> [0] https://dn.odroid.com/S922X/ODROID-N2/Datasheet/S922X_Public_Datasheet_V0.2.pdf
> 
> .
>