Re: [RESEND] mtd: spi-nor: Fix Cadence QSPI RCU Schedule Stall

From: <Tudor.Ambarus@microchip.com>
To: <thor.thayer@linux.intel.com>, <marek.vasut@gmail.com>,
	<dwmw2@infradead.org>, <computersforpeace@gmail.com>,
	<miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND] mtd: spi-nor: Fix Cadence QSPI RCU Schedule Stall
Date: Wed, 21 Aug 2019 08:22:19 +0000	[thread overview]
Message-ID: <5f0349e4-e412-99a5-ea86-f8fb572b0ed7@microchip.com> (raw)
In-Reply-To: <1565909736-11379-1-git-send-email-thor.thayer@linux.intel.com>

On 08/16/2019 01:55 AM, thor.thayer@linux.intel.com wrote:
> External E-Mail
> 
> 
> From: Thor Thayer <thor.thayer@linux.intel.com>
> 
> The current Cadence QSPI driver sometimes caused a
> "rcu_sched self-detected stall" while writing large files.
> 
> Stall Report:
> '# mtd_debug write /dev/mtd1 0 48816464 blob.img
> [ 1815.454227] rcu: INFO: rcu_sched self-detected stall on CPU
> [ 1815.459789] rcu:     0-....: (2099 ticks this GP) idle=8c6/1/0x40000002
>  softirq=6492/6492 fqs=935
> [ 1815.468442] rcu:      (t=2100 jiffies g=8749 q=247)
> 	<snip> (abbreviated backtrace)
> [ 1815.772086] [<c05a3ea0>] (cqspi_exec_flash_cmd) (cqspi_read_reg)
> [ 1815.786203] [<c05a5488>] (cqspi_read_reg) from (read_sr)
> [ 1815.803790] [<c05a0330>] (read_sr) from
> 	(spi_nor_wait_till_ready_with_timeout)
> [ 1815.816610] [<c05a182c>] (spi_nor_wait_till_ready_with_timeout) from
> 	(spi_nor_write+0x104/0x1d0)
> [ 1815.836791] [<c05a1a44>] (spi_nor_write) from (part_write+0x50/0x58)
> 	<snip>
> [ 1815.997961] cadence-qspi ff809000.spi: Flash command execution timed out.
> [ 1816.004733] error -110 reading SR
> file_to_flash: write, size 0x2e8e150, n 0x2e8e150
> write(): Connection timed out
> 
> This was caused by a tight loop in cqspi_wait_for_bit(). Fix by using
> readl_relaxed_poll_timeout() which sleeps 10us while polling a register.
> 
> Fit onto 80 character line by truncating the bool clear parameter
> 
> Fixes: 140623410536 ("mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller")
> Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
> ---
>  drivers/mtd/spi-nor/cadence-quadspi.c | 19 +++++--------------
>  1 file changed, 5 insertions(+), 14 deletions(-)
> 

Since the bug was not introduced in the previous release and we are quite late
for mtd/fixes,

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git,
spi-nor/next branch.

Thanks,
ta
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