From: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Oleksandr Suvorov
<oleksandr.suvorov-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
Cc: "linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Oleksandr Suvorov
<cryosay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Marcel Ziswiler
<marcel.ziswiler-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>,
Igor Opanyuk
<igor.opanyuk-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>,
Philippe Schenker
<philippe.schenker-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
Subject: Re: [PATCH 2/2] spi: spidev: fix a max speed setting
Date: Thu, 20 Feb 2020 18:42:01 +0000 [thread overview]
Message-ID: <20200220184201.GE3926@sirena.org.uk> (raw)
In-Reply-To: <20200220141143.3902922-3-oleksandr.suvorov-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
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On Thu, Feb 20, 2020 at 02:11:51PM +0000, Oleksandr Suvorov wrote:
> SPI_IOC_WR_MAX_SPEED_HZ command always sets spi->max_speed_hz
> to the initial value come from DT.
This is intentional. It's doing a call to spi_setup() then restoring
the original value, the goal being just to run spi_setup() with the new
value - it's not really a good idea to change the maximum speed in the
first place.
> It leads to set a wrong max speed with IOCTL call.
In what way does it lead to the wrong speed being set?
> Fix the logic of a max speed assignment.
If the expectation is that the default speed should be changed for the
device this should be handled at the spidev level rather than in the
core.
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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Cc: "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Oleksandr Suvorov <cryosay@gmail.com>,
Marcel Ziswiler <marcel.ziswiler@toradex.com>,
Igor Opanyuk <igor.opanyuk@toradex.com>,
Philippe Schenker <philippe.schenker@toradex.com>
Subject: Re: [PATCH 2/2] spi: spidev: fix a max speed setting
Date: Thu, 20 Feb 2020 18:42:01 +0000 [thread overview]
Message-ID: <20200220184201.GE3926@sirena.org.uk> (raw)
In-Reply-To: <20200220141143.3902922-3-oleksandr.suvorov@toradex.com>
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On Thu, Feb 20, 2020 at 02:11:51PM +0000, Oleksandr Suvorov wrote:
> SPI_IOC_WR_MAX_SPEED_HZ command always sets spi->max_speed_hz
> to the initial value come from DT.
This is intentional. It's doing a call to spi_setup() then restoring
the original value, the goal being just to run spi_setup() with the new
value - it's not really a good idea to change the maximum speed in the
first place.
> It leads to set a wrong max speed with IOCTL call.
In what way does it lead to the wrong speed being set?
> Fix the logic of a max speed assignment.
If the expectation is that the default speed should be changed for the
device this should be handled at the spidev level rather than in the
core.
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next prev parent reply other threads:[~2020-02-20 18:42 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 14:11 [PATCH 0/2] trivial fixes for fsl-spi and spidev Oleksandr Suvorov
2020-02-20 14:11 ` Oleksandr Suvorov
[not found] ` <20200220141143.3902922-1-oleksandr.suvorov-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
2020-02-20 14:11 ` [PATCH 1/2] spi: fsl-lpspi: remove unneeded array Oleksandr Suvorov
2020-02-20 14:11 ` Oleksandr Suvorov
[not found] ` <20200220141143.3902922-2-oleksandr.suvorov-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
2020-03-03 17:08 ` Applied "spi: fsl-lpspi: remove unneeded array" to the spi tree Mark Brown
2020-03-03 17:08 ` Mark Brown
2020-02-20 16:47 ` [PATCH 0/2] trivial fixes for fsl-spi and spidev Mark Brown
2020-02-20 16:47 ` Mark Brown
2020-02-20 14:11 ` [PATCH 2/2] spi: spidev: fix a max speed setting Oleksandr Suvorov
[not found] ` <20200220141143.3902922-3-oleksandr.suvorov-2KBjVHiyJgBBDgjK7y7TUQ@public.gmane.org>
2020-02-20 18:42 ` Mark Brown [this message]
2020-02-20 18:42 ` Mark Brown
[not found] ` <20200220184201.GE3926-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2020-02-21 12:43 ` Oleksandr Suvorov
2020-02-21 12:43 ` Oleksandr Suvorov
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