lkml.org 
[lkml]   [2014]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] i2c: designware: prevent early stop on TX FIFO empty
Hi Wolfram,

On Wed, Nov 19, 2014 at 10:21:22AM +0100, Wolfram Sang wrote:
> On Fri, Nov 07, 2014 at 12:10:44PM +0000, Andrew Jackson wrote:
> > If the Designware core is configured with IC_EMPTYFIFO_HOLD_MASTER_EN
> > set to zero, allowing the TX FIFO to become empty causes a STOP
> > condition to be generated on the I2C bus. If the transmit FIFO
> > threshold is set too high, an erroneous STOP condition can be
> > generated on long transfers - particularly where the interrupt
> > latency is extended.
> >
> > Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
>
> So, what do other designware users think of this change (nice CC list
> BTW, Andrew). Adding Mika, too.

I don't have access to this hardware anymore so I can't test. As far as I
remember the spec this change should be OK.

baruch

> > drivers/i2c/busses/i2c-designware-core.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> > index 3c20e4b..e070edd 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.c
> > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > @@ -363,7 +363,7 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
> > }
> >
> > /* Configure Tx/Rx FIFO threshold levels */
> > - dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL);
> > + dw_writel(dev, dev->tx_fifo_depth / 2, DW_IC_TX_TL);
> > dw_writel(dev, 0, DW_IC_RX_TL);
> >
> > /* configure the i2c master */

--
http://baruch.siach.name/blog/ ~. .~ Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
- baruch@tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -


\
 
 \ /
  Last update: 2014-11-19 15:01    [W:0.086 / U:0.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site