[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAOiHx==3emNU_Tnc952g7fWi9eSTDNq2-fi9KiAQ9Gfiv011Yw@mail.gmail.com>
Date: Fri, 1 May 2015 12:50:04 +0200
From: Jonas Gorski <jogo@...nwrt.org>
To: Michal Suchanek <hramrach@...il.com>
Cc: Marek Vasut <marex@...x.de>,
Geert Uytterhoeven <geert+renesas@...der.be>,
David Woodhouse <dwmw2@...radead.org>,
"Rafa?? Mi??ecki" <zajec5@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
MTD Maling List <linux-mtd@...ts.infradead.org>,
"grmoore@...era.com" <grmoore@...era.com>,
Brian Norris <computersforpeace@...il.com>,
Ben Hutchings <ben@...adent.org.uk>,
Alison Chaiken <alison_chaiken@...tor.com>,
"Bean Huo (beanhuo)" <beanhuo@...ron.com>
Subject: Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.
Hi,
On Fri, May 1, 2015 at 9:05 AM, Michal Suchanek <hramrach@...il.com> wrote:
> On 1 May 2015 at 01:13, Marek Vasut <marex@...x.de> wrote:
>> On Thursday, April 30, 2015 at 11:13:12 PM, Michal Suchanek wrote:
>>> The sector size of the flash memory is unclear from datasheet or may
>>> possibly vary between chips so add a flag to always use 4k blocks.
>>>
>>> Currently 4k blocks are always used when possible but in the future
>>> somebody might want to do some optimizations with sector erase.
>>>
>>> Signed-off-by: Michal Suchanek <hramrach@...il.com>
>>
>> I _think_ you might be able to determine the size, no ?
>>
>> One way is to ask the vendor, but you can also try something like:
>> 1) erase the whole SPI NOR
>> 2) overwrite it with zeroes (or ones ? I think it should be all ones after
>> erasing).
>> 3) Erase sector 0
>> 4) Read some 128 KiB back
>> 5) Observe what is the difference.
>>
>
> I can determine it for this particular chip. However, when the vendor
> datasheet says the block is 64/32K it might mean that chips with this
> ID can have either block size.
>
> It's a value that we don't use anyway so I just mark it as unknown
> here for future reference.
It will be used if MTD_SPI_NOR_USE_4K_SECTORS is unset, so you should
add some code to properly handle that case.
Also I'd suggest switching the order of 2 and 3, so you add the flag
handling first and then add support for a flash chip with this issue.
Regards
Jonas
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists