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From: Mark Brown <>
To: Chris Ruehl <>
Cc: Sascha Hauer <>,,,,
Subject: Re: [PATCH] spi-imx: imx6q add single burst transfer support
Date: Wed, 1 Jun 2016 15:32:13 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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On Wed, Jun 01, 2016 at 03:09:13PM +0800, Chris Ruehl wrote:
> On Wednesday, June 01, 2016 02:54 PM, Sascha Hauer wrote:

> > > The patch add support for single burst transfer where chipselect will
> > > hold active until transfer completes with a limit to 2^7 words transferred.
> > > The single-burst-mode need set the burstlength in ECSPI_CONREG.BURST_LENGTH
> > > and clear the ecspi channel related ss_ctl flag in ECSPI_CONFIGREG.SS_CTL.

> > > The single-burst-mode is disabled by default. The activation from spidev

> > Erm, no. This is not acceptable in many ways. First of all the SPI API
> > between the kernel and userspace is driver agnostic. There is simply no
> > place for passing driver specific quirks from userspace to the spi-imx
> > driver. Then there is no API change needed because the way SPI
> > messages should be translated to the wire is well defined, the spi-imx
> > driver is just doing it wrong in this case which might be worth fixing.
> > This could be done without passing a "do it right" flag to the driver.

> I expected AND except the "NO" on this!
> But the userspace interface (xfer) does not have anything else then
> tx,rx-buf cs_change delay.. to carry infos forward to the driver.

That's absolutely fine.  The "new" behaviour which you are introducing
is the standard behaviour, the fact that the driver currently does
anything different is just a very bad bug in the driver.  Instead of
introducing a new option to provide a driver specific "make it work"
quirk that users must activate you should fix the driver to perform
correctly as standard.

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  parent reply	other threads:[~2016-06-01 14:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-01  4:50 Chris Ruehl
     [not found] ` <>
2016-06-01  5:06   ` Chris Ruehl
2016-06-01  6:54   ` Sascha Hauer
     [not found]     ` <>
2016-06-01  7:09       ` Chris Ruehl
     [not found]         ` <>
2016-06-01 14:32           ` Mark Brown [this message]
     [not found]             ` <>
2016-06-02  1:27               ` Chris Ruehl

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