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From: Stephen Boyd <swboyd@chromium.org>
To: Douglas Anderson <dianders@chromium.org>,
	Mark Brown <broonie@kernel.org>
Cc: msavaliy@qti.qualcomm.com, akashast@codeaurora.org,
	Roja Rani Yarubandi <rojay@codeaurora.org>,
	Douglas Anderson <dianders@chromium.org>,
	Alok Chauhan <alokc@codeaurora.org>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Dilip Kota <dkota@codeaurora.org>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-spi@vger.kernel.org
Subject: Re: [PATCH v3 2/4] spi: spi-geni-qcom: Fail new xfers if xfer/cancel/abort pending
Date: Thu, 17 Dec 2020 18:54:09 -0800	[thread overview]
Message-ID: <160826004928.1580929.14421632210433013822@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20201217142842.v3.2.Ibade998ed587e070388b4bf58801f1107a40eb53@changeid>

Quoting Douglas Anderson (2020-12-17 14:29:12)
> If we got a timeout when trying to send an abort command then it means
> that we just got 3 timeouts in a row:
> 
> 1. The original timeout that caused handle_fifo_timeout() to be
>    called.
> 2. A one second timeout waiting for the cancel command to finish.
> 3. A one second timeout waiting for the abort command to finish.
> 
> SPI is clocked by the controller, so nothing (aside from a hardware
> fault or a totally broken sequencer) should be causing the actual
> commands to fail in hardware.  However, even though the hardware
> itself is not expected to fail (and it'd be hard to predict how we
> should handle things if it did), it's easy to hit the timeout case by
> simply blocking our interrupt handler from running for a long period
> of time.  Obviously the system is in pretty bad shape if a interrupt
> handler is blocked for > 2 seconds, but there are certainly bugs (even
> bugs in other unrelated drivers) that can make this happen.
> 
> Let's make things a bit more robust against this case.  If we fail to
> abort we'll set a flag and then we'll block all future transfers until
> we have no more interrupts pending.
> 
> Fixes: 561de45f72bd ("spi: spi-geni-qcom: Add SPI driver support for GENI based QUP")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

  reply	other threads:[~2020-12-18  2:55 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-17 22:29 [PATCH v3 1/4] spi: spi-geni-qcom: Fix geni_spi_isr() NULL dereference in timeout case Douglas Anderson
2020-12-17 22:29 ` [PATCH v3 2/4] spi: spi-geni-qcom: Fail new xfers if xfer/cancel/abort pending Douglas Anderson
2020-12-18  2:54   ` Stephen Boyd [this message]
2020-12-17 22:29 ` [PATCH v3 3/4] spi: spi-geni-qcom: Don't try to set CS if an xfer is pending Douglas Anderson
2020-12-18  2:54   ` Stephen Boyd
2020-12-17 22:29 ` [PATCH v3 4/4] spi: spi-geni-qcom: Print an error when we timeout setting the CS Douglas Anderson
2020-12-18  2:54   ` Stephen Boyd
2020-12-18 18:29 ` [PATCH v3 1/4] spi: spi-geni-qcom: Fix geni_spi_isr() NULL dereference in timeout case Mark Brown
2021-03-01 19:59 ` patchwork-bot+linux-arm-msm

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