Re: [PATCH] mtd: spi-nor: add support for Winbond W25Q512JV

[David Bauer <mail@david-bauer.net>]

Hi Shuhao,

Sorry for coming back late to this.

On 3/10/21 8:41 AM, Shuhao Mai wrote:
> On Tue, Mar 09, 2021 at 07:53:59AM +0000, Tudor.Ambarus@microchip.com wrote:
>> On 3/8/21 8:03 PM, David Bauer wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> Hi Tudor,
>>>
>>> On 3/8/21 6:50 AM, Tudor.Ambarus@microchip.com wrote:
>>>> On 2/13/21 5:10 PM, David Bauer wrote:
>>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>>
>>>>> The Winbond W25Q512JV is a 512mb SPI-NOR chip. It supports 4K
>>>>> sectors as well as block protection and Dual-/Quad-read.
>>>>>
>>>>> Tested on: Ubiquiti UniFi 6 LR
>>>>>
>>>>> Signed-off-by: David Bauer <mail@david-bauer.net>
>>>>
>>>> David, I'll take Shuhao's patch because he sent it first:
>>>> https://patchwork.ozlabs.org/project/linux-mtd/patch/20210208075303.4200-1-shuhao.mai.1990@gmail.com/
>>>
>>> Fine with me, I have not found this patch :)
>>>
>>>>
>>>> Would you make an incremental patch on top op Shuhao's, to add the
>>>> locking support?
>>>
>>> Sure, It's necessary for the board (UniFi 6 LR), as the bootloader locks the flash on boot.
>>
>> Is it necessary to unlock the flash at boot time?
>> You can unlock the flash from user-space, using mtd-utils.
>>
>> Have you tried to lock/unlock portions of the flash using mtd-utils,
>> and check if what was locked corresponds to what the datasheet indicates?
>>
>>>
>>> I'll send a new patch for the lock support.
>>>
>> Great, thanks!
>> ta
> 
> Hi Tudor and David,
> 
> 
> I made a quick test on flash_lock with kernel 5.8.18 and mtd-utils
> v2.1.2. It returns "could not lock device: /dev/mtd0" and "error 22
> (Invalid argument)".
> 
> Could be the error caused by my test environment, if it's functional on
> UniFi 6 LR.
Were these partitions starting with the first / ending with the last block on the flash chip?
Locking / unlocking mtd partitions not aligned at the beginning / end of the chip sound will
return invalid argument.

For the UniFi 6 LR, these flags are required, as otherwise the lower half of the flash
remains write protected (the bootloader actively enables this protection for whatever reason).

I'll send a rebased patch adding the required flags shortly.

Best wishes
David

> 
> 
> Sincerely
> Shuhao
> 

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