linux-kernel - Re: [PATCH] mtd: rawnand: denali: fix a race condition when DMA is kicked

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Message-ID: <20180914162923.05c44fcc@xps13>
Date:   Fri, 14 Sep 2018 16:29:23 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-mtd@...ts.infradead.org,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Steffen Trumtrar <s.trumtrar@...gutronix.de>,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] mtd: rawnand: denali: fix a race condition when DMA is
 kicked

Hello,

Masahiro Yamada <yamada.masahiro@...ionext.com> wrote on Thu, 13 Sep
2018 14:58:49 +0900:

> I thought the read-back of the DMA_ENABLE register was unnecessary
> (at least it is working on my boards), then deleted it in commit
> 586a2c52909d ("mtd: nand: denali: squash denali_enable_dma() helper
> into caller").  Sorry, I was wrong - it caused a timing issue on
> Cyclone5 SoCFPGAs.
> 
> Revive the register read-back, commenting why this is necessary.
> 
> Fixes: 586a2c52909d ("mtd: nand: denali: squash denali_enable_dma() helper into caller")
> Reported-by: Steffen Trumtrar <s.trumtrar@...gutronix.de>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Reviewed-by: Miquel Raynal <miquel.raynal@...tlin.com>


Thanks,
Miquèl