linux-kernel - Re: [PATCH 0/5] spi: zynqmp-gqspi: Improve error recovery by resetting

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Message-ID: <c1a3f172-700e-4079-a501-b3f3f08b41aa@sirena.org.uk>
Date: Mon, 20 Jan 2025 13:49:53 +0000
From: Mark Brown <broonie@...nel.org>
To: Sean Anderson <sean.anderson@...ux.dev>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
	Michal Simek <michal.simek@....com>, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jinjie Ruan <ruanjinjie@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>,
	Conor Dooley <conor+dt@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH 0/5] spi: zynqmp-gqspi: Improve error recovery by
 resetting

On Fri, Jan 17, 2025 at 04:46:23PM -0500, Sean Anderson wrote:
> On 1/17/25 13:41, Mark Brown wrote:
> > On Fri, Jan 17, 2025 at 07:31:08PM +0100, Miquel Raynal wrote:

> >> Yes, unless the timeout is reached for "good reasons", ie. you request
> >> substantial amounts of data (typically from a memory device) and the
> >> timeout is too short compared to the theoretical time spent in the
> >> transfer. A loaded machine can also increase the number of false
> >> positives I guess.

> > I'd argue that all of those are bad reasons, I'd only expect us to time
> > out when there's a bug - choosing too low a timeout or doing things in a
> > way that generates timeouts under load is a problem.

> There's no transmit DMA for this device. So if you are under high load
> and make a long transfer, it's possible to time out. I don't know if
> it's possible to fix that very easily. The timeout calculation assumes
> that data is being transferred at the SPI bus rate.

In that case I wouldn't expect the timeout to apply to the whole
operation, or I'd expect a timeout applied waiting for something
interrupt driven to not to be fired unless we stop making forward
progress.  

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