[PATCH 2/2] spi: davinci: support adding delay between transmission

Hi Mark,

On 09/06/2014 05:31 PM, Mark Brown wrote:

On Fri, Sep 05, 2014 at 05:21:56PM +0300, Grygorii Strashko wrote:

quoted

I think we have some misunderstanding here :(
1) All new properties a optional and should be specified for SPI Slave devices
2) Seems we are talking using different terms:
- you referring to the term "transfers" - sequence of packets.
   Each packet is one transfer (array of words).
- while these new properties affect on "transmissions" - sequence of words.
   Each word is one transmission.

That's *very* unusual terminology which doesn't match my expectations at
all.  Please describe words as words, that'll be much more obvious.

These terms are used in DM/TRM :(

I'll split this patch and first introduce WDELAY, C2TDELAY, T2CDELAY
(with updated documentation).
The only question is - Should they be somehow common or specific for spi-davinci?

quoted

Also, below is additional information about properties which
are used in 5-pin mode (SPI_READY) to improve error detection
[OMAP-L138/da830 - http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf]:

This is a *whole* other thing, please split these out and work on this
separately.  The client device is going to need to be doing the same
thing here so implementing this as a local option in the controller
driver isn't the best way forwards.

quoted

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SPIFMTn[23].PARPOL - Parity polarity: even or odd. PARPOL can be modified in privilege mode only.
   0 An even parity flag is added at the end of the transmit data stream.
   1 An odd parity flag is added at the end of the transmit data stream.

quoted

quoted

Why would these be specified in DT and not with runtime flags enabled by
the device?  It looks like they affect the data stream generated by the
controller so the client device needs to know about them; I'd expect
that it's device driver would be controlling when they are enabled if
the controller supports them.

quoted

Could you clarify, pls - Do you mean that struct spi_device.mode and
common SPI DT bindings should be extended to support this?

Yes, if they aren't something that's purely internal to the device they
need to be generic so that both devices can be configured appropriately.

Regards,
-grygorii