From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Chuanhong Guo <gch981213@gmail.com>
Cc: Stefan Roese <sr@denx.de>, Vignesh Raghavendra <vigneshr@ti.com>,
Boris Brezillon <bbrezillon@kernel.org>,
David Woodhouse <dwmw2@infradead.org>,
linux-kernel@vger.kernel.org,
Frieder Schrempf <frieder.schrempf@kontron.de>,
linux-mtd@lists.infradead.org,
Richard Weinberger <richard@nod.at>,
Brian Norris <computersforpeace@gmail.com>,
Jeff Kletsky <git-commits@allycomm.com>
Subject: Re: [PATCH][RFC] mtd: spinand: fix detection of GD5FxGQ4xA flash
Date: Mon, 28 Oct 2019 17:41:31 +0100 [thread overview]
Message-ID: <20191028174131.65c3d580@xps13> (raw)
In-Reply-To: <20191016013845.23508-1-gch981213@gmail.com>
Hello,
Chuanhong Guo <gch981213@gmail.com> wrote on Wed, 16 Oct 2019 09:38:24
+0800:
> GD5FxGQ4xA didn't follow the SPI spec to keep MISO low while slave is
> reading, and instead MISO is kept high. As a result, the first byte
> of id becomes 0xFF.
> Since the first byte isn't supposed to be checked at all, this patch
> just removed that check.
>
> While at it, redo the comment above to better explain what's happening.
>
> Fixes: cfd93d7c908e ("mtd: spinand: Add support for GigaDevice GD5F1GQ4UFxxG")
> Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
> CC: Jeff Kletsky <git-commits@allycomm.com>
> ---
> RFC:
> I doubt whether this patch is a proper fix for the underlying problem:
> The actual problem is that we have two different implementation of read id
> command: One replies immediately after master sending 0x9f and the other
> need to send 0x9f and an offset byte (found in winbond and early GD flashes.)
> Current code only works if SPI master is properly implemented (i.e. keep MOSI
> low while reading.)
I am not entirely against the fix, but this is a SPI host controller
issue, right? Can you try to fix the controller driver instead?
Thanks,
Miquèl
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next prev parent reply other threads:[~2019-10-28 16:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 1:38 [PATCH][RFC] mtd: spinand: fix detection of GD5FxGQ4xA flash Chuanhong Guo
2019-10-28 16:41 ` Miquel Raynal [this message]
2019-11-03 12:03 ` Chuanhong Guo
2019-11-03 13:27 ` Boris Brezillon
2019-11-05 18:20 ` Miquel Raynal
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