From: David Brownell <david-b@pacbell.net>
To: spi-devel-general@lists.sourceforge.net
Cc: "Hemanth V" <hemanthv@ti.com>, linux-omap@vger.kernel.org
Subject: Re: [spi-devel-general] [RESEND][PATCH 0/2] McSPI Slave and DMA , FIFO support
Date: Thu, 27 Aug 2009 22:42:20 -0700 [thread overview]
Message-ID: <200908272242.20636.david-b@pacbell.net> (raw)
In-Reply-To: <007b01c9fe05$9e5baeb0$LocalHost@wipultra793>
On Sunday 05 July 2009, Hemanth V wrote:
> Do you see any major changes required to support
> slave mode in the SPI core driver.
There *is* no such thing as a "SPI core driver"...
> We are able to
> use the existing interface for slave mode also, but
> some APIs/ Structures could be made generic.
Three things are obvious:
- A spi_master is not a slave side driver!
- Control model would need to be inverted
* Chip select would be one input,
not N outputs
* No clock rate controls at all
* latency issues ... driver can't necessarily
respond quickly enough to guarantee no data
loss (FIFOs help)
* Can't re-use /dev/spidev*
* Request queue would have a very different role
- Some primitives are likely missing, for flow
control (when hardware has a READY handshake)
I think a few proposals for how to handle slave
side have been circulated.
next prev parent reply other threads:[~2009-08-28 5:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-23 13:53 [RESEND][PATCH 0/2] McSPI Slave and DMA ,FIFO support Hemanth V
2009-07-03 0:05 ` David Brownell
2009-07-06 6:47 ` Hemanth V
2009-08-28 5:42 ` David Brownell [this message]
2009-08-28 12:05 ` [spi-devel-general] [RESEND][PATCH 0/2] McSPI Slave and DMA , FIFO support Hemanth V
2009-08-28 16:10 ` Tony Lindgren
2009-08-28 17:32 ` David Brownell
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