From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neil@brown.name>
Subject: Re: [PATCH] mtd: spi-nor: honour max_data_size for spi-nor writes
Date: Wed, 13 Jun 2018 08:24:26 +1000
Message-ID: <87sh5riqxx.fsf@notabene.neil.brown.name>
References: <1528708694-19407-1-git-send-email-yogeshnarayan.gaur@nxp.com> <20180611114916.351ed272@bbrezillon> <87r2ldj7xi.fsf@notabene.neil.brown.name> <20180612092248.4e6a3e92@bbrezillon>
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Cc: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>,
        linux-mtd@lists.infradead.org, boris.brezillon@free-electrons.com,
        frieder.schrempf@exceet.de, computersforpeace@gmail.com,
        david.wolfe@nxp.com, han.xu@nxp.com, festevam@gmail.com,
        marek.vasut@gmail.com, prabhakar.kushwaha@nxp.com,
        linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org
To: Boris Brezillon <boris.brezillon@bootlin.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20180612092248.4e6a3e92@bbrezillon>
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On Tue, Jun 12 2018, Boris Brezillon wrote:

>
> Just because you managed to solve the problem in one driver does not
> mean the problem does not exist for others. I read this datasheet [1]
> several times and couldn't find a way to say 'I want to keep the CS
> asserted between 2 transactions', so I think we really need this patch.

I agree that my experience doesn't necessarily generalize.  As the patch
carried by signed-off-by (even though I only wrote little parts of it) I
wanted to make it clear that I had no desire to promote the patch -
maybe I stated that too strongly.

Thanks for the link to the data sheet.  I had a bit of a look, but
reading these things must be an art that I haven't fully mastered yet -
it would probably take me a few days to really understand it.
The Programmable Sequence Enginine (Section 10.2.5.3.1) seems
interesting. I wouldn't be surprised that that lets you do interesting
things.

It is obviously quite a powerful unit and it is surprising - to me -
that it might not allow arbitrarily long messages, but I cannot justify
the time to really dig in and see if that is the case.
Maybe you are right.  I have no particular objections to the patch, I
just don't want to be seen as speaking in favour of it.

Thanks,
NeilBrown


>
> Regards,
>
> Boris
>
> [1]https://www.nxp.com/docs/en/reference-manual/VFXXXRM.pdf

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