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From: Mark Brown <broonie@kernel.org>
To: Serge Semin <fancer.lancer@gmail.com>
Cc: Tudor Ambarus <tudor.ambarus@microchip.com>,
	linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] spi: Limit the spi device max speed to controller's max speed
Date: Wed, 9 Dec 2020 19:54:20 +0000	[thread overview]
Message-ID: <20201209195420.GD4790@sirena.org.uk> (raw)
In-Reply-To: <20201209194636.32f4ioxxdggezklr@mobilestation>

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On Wed, Dec 09, 2020 at 10:46:36PM +0300, Serge Semin wrote:

> On Wed, Dec 09, 2020 at 07:35:14PM +0200, Tudor Ambarus wrote:

> > Make sure the max_speed_hz of spi_device does not override
> > the max_speed_hz of controller.

> I have doubts that's right thing to do. It seems better to let
> the controller driver to handle the speed clamping itself, while
> to leave the SPI client device max_speed_hz field describing the
> device speed capability. Moreover the SPI-transfers passed to the
> controller will have a SPI-bus speed fixed in accordance with the
> controller and client device capabilities anyway.
> See the __spi_validate() method for details:
> https://elixir.bootlin.com/linux/v5.10-rc7/source/drivers/spi/spi.c#L3570

Right, in general we aim to do this sort of fixup on the transfers
and messages rather than the devices, I guess we might be missing
validation in some of the flash acceleration paths or was this an issue
seen through inspection?

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  reply	other threads:[~2020-12-09 19:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09 17:35 [PATCH] spi: Limit the spi device max speed to controller's max speed Tudor Ambarus
2020-12-09 19:46 ` Serge Semin
2020-12-09 19:54   ` Mark Brown [this message]
2020-12-09 20:15     ` Serge Semin
2020-12-09 20:25       ` Mark Brown
2020-12-09 20:30         ` Serge Semin
2020-12-10  8:58           ` Tudor.Ambarus
2020-12-10 15:33             ` Mark Brown
2020-12-10 16:32               ` Tudor.Ambarus
2020-12-10 18:16                 ` Mark Brown
2020-12-11 17:51 ` Mark Brown
2020-12-15 14:24   ` Geert Uytterhoeven
2020-12-16  8:25     ` Tudor.Ambarus

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