lkml.org 
[lkml]   [2020]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RESEND PATCH 1/2] mtd: spi-nor: do not touch TB bit without SPI_NOR_HAS_TB
From
Date


On 9/30/20 6:37 PM, Ivan Mikhaylov wrote:
> On Wed, 2020-09-30 at 15:06 +0530, Vignesh Raghavendra wrote:
>>
>> On 9/21/20 4:54 PM, Ivan Mikhaylov wrote:
>>> Some chips like macronix don't have TB(Top/Bottom protection)
>>> bit in the status register. Do not write tb_mask inside status
>>> register, unless SPI_NOR_HAS_TB is present for the chip.
>>>
>>
>> Not entirely accurate.. Macronix chips have TB bit in config register
>> and is OTP and hence should not be touched ideally...
>>
>> You still need to "read" that bit to determine actual scheme (Top vs
>> Bottom). This is needs to be done before 2/2 enables SPI_NOR_HAS_LOCK
>> flag for macronix flashes.
>
> Vignesh, that's the point about this commit to generalize this part about TB bit
> plus there is already exist SPI_NOR_HAS_TB flag which representing state of TB
> existence. I didn't add any support for macronix's TB bit, that's true but
> that's enough to make macronix chips able to use lock mechanism with default
> 'use_top' or any other chips which doesn't have TB bit.

Right, but 2/2 "enables" locking mechanism for Macronix flashes. Therefore its
necessary to take TB bit into account so that implementation is correct.
What if OTP bit is set as "use_bottom"? Although this is non default,
we need to take care of this case for correctness.

>
>> I guess macronix does not support SR_SRWD right? This needs special
>> treatment as well.
>
> It does support SR_SRWD as well. No need any special treatment here.
>

I did not find it in one Macronix datasheet at least:
https://www.macronix.com/Lists/Datasheet/Attachments/7902/MX25L25673G,%203V,%20256Mb,%20v1.6.pdf

Are you sure all Macronix flashes support SRWD?

> Thanks.
>

\
 
 \ /
  Last update: 2020-09-30 16:01    [W:0.046 / U:1.488 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site