linux-kernel - RE: [PATCH] serial: Add OMAP high-speed UART driver.

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Date:	Tue, 2 Mar 2010 19:34:06 +0530
From:	"Shilimkar, Santosh" <santosh.shilimkar@...com>
To:	"G, Manjunath Kondaiah" <manjugk@...com>,
	"S, Venkatraman" <svenkatr@...com>,
	Tony Lindgren <tony@...mide.com>,
	"Raja, Govindraj" <govindraj.raja@...com>,
	Greg KH <greg@...ah.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Olof Johansson <olof@...om.net>
Subject: RE: [PATCH] serial: Add OMAP high-speed UART driver.

<snip snip>
> > > --
> > CDAC is a shadow register used for monitoring the DMA channel.
> >  I think it would be a lot
> > simpler if omap_start_dma() always resets CDAC to 0, and the
> > UART driver
> > just not set it explicitly.
> 
> This seems to be better option than exposing CDAC read/write API
> to other drivers since user need to write '0' before starting any DMA
> transfer which can be be done in omap_start_dma().
> 
> I am wondering how other drivers are using DMA transfer API's without
> resetting CDAC to zero.
>
It's needed only if some one is interested in that count. UART seems to 
using this counter where as other driver don't.

Why do you think drivers need to know about counter value ?

Regards,
Santosh
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