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Subject: Re: Re: [PATCH 1/4] can: mcp251xfd: stop timestamp before sending chip to
 sleep
Date: Thu, 25 Apr 2024 07:14:47 +0200
From: Gregor Herburger <gregor.herburger@ew.tq-group.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Thomas Kopp <thomas.kopp@microchip.com>,
	Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, linux-can@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org, linux@ew.tq-group.com,
	alexander.stein@ew.tq-group.com
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References: <20240417-mcp251xfd-gpio-feature-v1-0-bc0c61fd0c80@ew.tq-group.com>
 <20240417-mcp251xfd-gpio-feature-v1-1-bc0c61fd0c80@ew.tq-group.com>
 <20240424-fast-sandy-jackrabbit-d289a0-mkl@pengutronix.de>
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In-Reply-To: <20240424-fast-sandy-jackrabbit-d289a0-mkl@pengutronix.de>

On Wed, Apr 24, 2024 at 10:24:58AM +0200, Marc Kleine-Budde wrote:
> On 17.04.2024 15:43:54, Gregor Herburger wrote:
> > MCP2518FD exits Low-Power Mode (LPM) when CS is asserted. When chip
> > is send to sleep and the timestamp workqueue is not stopped chip is
> > waked by SPI transfer of mcp251xfd_timestamp_read.
> > 
> > So before sending chip to sleep stop timestamp otherwise the
> > mcp251xfd_timestamp_read callback would wake chip up.
> > 
> > Also there are error paths in mcp251xfd_chip_start where workqueue has
> > not been initialized but mcp251xfd_chip_stop is called. So check for
> > initialized func before canceling delayed_work.
> 
> Can you move the mcp251xfd_timestamp_init() (which starts the
> timestamping worker) into mcp251xfd_chip_start() to keep things
> symmetrical? I think then you don't need to check for "work->func" in
> mcp251xfd_timestamp_stop().
> 
Hi Marc,

I realise now I confused mcp251xfd_timestamp_init with
mcp251xfd_chip_timestamp_init.

The only call chip mcp251xfd_chip_stop without call to
mcp251xfd_timestamp_stop is from mcp251xfd_handle_cerrif.

So it should be sufficient to stop the worker there and the check for
"work->func" can be also omitted.

Best regards,
Gregor
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