Re: [PATCH v2 stable 5.10] mtd: rawnand: gpmi: Set WAIT_FOR_READY timeout based on program/erase times

From: Greg KH <greg@kroah.com>
To: Tim Harvey <tharvey@gateworks.com>
Cc: "Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Tomasz Moń" <tomasz.mon@camlingroup.com>,
	"Richard Weinberger" <richard@nod.at>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	"Sasha Levin" <sashal@kernel.org>, "Han Xu" <han.xu@nxp.com>,
	kernel <kernel@pengutronix.de>, stable <stable@vger.kernel.org>
Subject: Re: [PATCH v2 stable 5.10] mtd: rawnand: gpmi: Set WAIT_FOR_READY timeout based on program/erase times
Date: Mon, 7 Nov 2022 10:12:31 +0100	[thread overview]
Message-ID: <Y2jL/8zu90UizMGF@kroah.com> (raw)
In-Reply-To: <20221103153341.2600899-1-tharvey@gateworks.com>

On Thu, Nov 03, 2022 at 08:33:41AM -0700, Tim Harvey wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> commit 0fddf9ad06fd9f439f137139861556671673e31c upstream.
> 
> 06781a5026350 Fixes the calculation of the DEVICE_BUSY_TIMEOUT register
> value from busy_timeout_cycles. busy_timeout_cycles is calculated wrong
> though: It is calculated based on the maximum page read time, but the
> timeout is also used for page write and block erase operations which
> require orders of magnitude bigger timeouts.
> 
> Fix this by calculating busy_timeout_cycles from the maximum of
> tBERS_max and tPROG_max.
> 
> This is for now the easiest and most obvious way to fix the driver.
> There's room for improvements though: The NAND_OP_WAITRDY_INSTR tells us
> the desired timeout for the current operation, so we could program the
> timeout dynamically for each operation instead of setting a fixed
> timeout. Also we could wire up the interrupt handler to actually detect
> and forward timeouts occurred when waiting for the chip being ready.
> 
> As a sidenote I verified that the change in 06781a5026350 is really
> correct. I wired up the interrupt handler in my tree and measured the
> time between starting the operation and the timeout interrupt handler
> coming in. The time increases 41us with each step in the timeout
> register which corresponds to 4096 clock cycles with the 99MHz clock
> that I have.
> 
> Fixes: 06781a5026350 ("mtd: rawnand: gpmi: Fix setting busy timeout setting")
> Fixes: b1206122069aa ("mtd: rawniand: gpmi: use core timings instead of an empirical derivation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Acked-by: Han Xu <han.xu@nxp.com>
> Tested-by: Tomasz Moń <tomasz.mon@camlingroup.com>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> ---
> v2: add sb tag and add upstream commit id

Now queued up, thanks.

greg k-h

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