From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Mark Brown <broonie@kernel.org>
Cc: Tudor Ambarus <tudor.ambarus@linaro.org>,
linux-spi@vger.kernel.org,
Nicolas Ferre <nicolas.ferre@microchip.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Claudiu Beznea <claudiu.beznea@microchip.com>,
linux-arm-kernel@lists.infradead.org,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH] spi: atmel: Prevent false timeouts on long transfers
Date: Fri, 16 Jun 2023 19:53:51 +0200 [thread overview]
Message-ID: <20230616195351.4976b702@xps-13> (raw)
In-Reply-To: <71245a47-5c7e-4ff4-80c3-3b2b4d3642db@sirena.org.uk>
Hi Mark,
broonie@kernel.org wrote on Fri, 16 Jun 2023 18:43:51 +0100:
> On Fri, Jun 16, 2023 at 06:59:06PM +0200, Miquel Raynal wrote:
> > broonie@kernel.org wrote on Fri, 16 Jun 2023 17:43:06 +0100:
> > > On Fri, Jun 16, 2023 at 06:15:35PM +0200, Miquel Raynal wrote:
> > > > broonie@kernel.org wrote on Fri, 16 Jun 2023 15:20:27 +0100:
>
> > > Like I say we should know the transfer speed so we can do better than
> > > 4ms/10k - we know how long it takes to clock out each byte, we can just
> > > multiply that by the size of the transfer then add some fudge factor for
> > > setup/teardown overhead. 1s feels pretty generous too. The sun6i
> > > driver for example does
>
> > > max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U)
>
> > > and just doubles the length based timeout with a minimum of 100ms which
> > > seems reasonable.
>
> > I already had issues with ~0.1s timeouts on NAND controllers, just
> > because the machine was heavily loaded. I believe we should avoid too
> > small timeouts, it does not make sense and make things worse under load.
>
> Well, we can raise that minimum if it's causing issues - 500ms say? 1s
> does feel a bit extreme for short transfers (and note that we'll use
> more than 100ms for long enough transfers).
Sounds reasonable. I believe it's worth the try.
Cheers,
Miquèl
WARNING: multiple messages have this Message-ID (diff)
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Mark Brown <broonie@kernel.org>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
linux-spi@vger.kernel.org,
Tudor Ambarus <tudor.ambarus@linaro.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Claudiu Beznea <claudiu.beznea@microchip.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] spi: atmel: Prevent false timeouts on long transfers
Date: Fri, 16 Jun 2023 19:53:51 +0200 [thread overview]
Message-ID: <20230616195351.4976b702@xps-13> (raw)
In-Reply-To: <71245a47-5c7e-4ff4-80c3-3b2b4d3642db@sirena.org.uk>
Hi Mark,
broonie@kernel.org wrote on Fri, 16 Jun 2023 18:43:51 +0100:
> On Fri, Jun 16, 2023 at 06:59:06PM +0200, Miquel Raynal wrote:
> > broonie@kernel.org wrote on Fri, 16 Jun 2023 17:43:06 +0100:
> > > On Fri, Jun 16, 2023 at 06:15:35PM +0200, Miquel Raynal wrote:
> > > > broonie@kernel.org wrote on Fri, 16 Jun 2023 15:20:27 +0100:
>
> > > Like I say we should know the transfer speed so we can do better than
> > > 4ms/10k - we know how long it takes to clock out each byte, we can just
> > > multiply that by the size of the transfer then add some fudge factor for
> > > setup/teardown overhead. 1s feels pretty generous too. The sun6i
> > > driver for example does
>
> > > max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U)
>
> > > and just doubles the length based timeout with a minimum of 100ms which
> > > seems reasonable.
>
> > I already had issues with ~0.1s timeouts on NAND controllers, just
> > because the machine was heavily loaded. I believe we should avoid too
> > small timeouts, it does not make sense and make things worse under load.
>
> Well, we can raise that minimum if it's causing issues - 500ms say? 1s
> does feel a bit extreme for short transfers (and note that we'll use
> more than 100ms for long enough transfers).
Sounds reasonable. I believe it's worth the try.
Cheers,
Miquèl
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next prev parent reply other threads:[~2023-06-16 17:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-16 14:12 [PATCH] spi: atmel: Prevent false timeouts on long transfers Miquel Raynal
2023-06-16 14:12 ` Miquel Raynal
2023-06-16 14:20 ` Mark Brown
2023-06-16 14:20 ` Mark Brown
2023-06-16 16:15 ` Miquel Raynal
2023-06-16 16:15 ` Miquel Raynal
2023-06-16 16:43 ` Mark Brown
2023-06-16 16:43 ` Mark Brown
2023-06-16 16:59 ` Miquel Raynal
2023-06-16 16:59 ` Miquel Raynal
2023-06-16 17:43 ` Mark Brown
2023-06-16 17:43 ` Mark Brown
2023-06-16 17:53 ` Miquel Raynal [this message]
2023-06-16 17:53 ` Miquel Raynal
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