On Mon, 25 Apr 2011 15:46:07 +0800 "Tang, Feng" <[email protected]> wrote:
> Hi Grant, > > On Thu, 31 Mar 2011 21:13:05 +0800 > Grant Likely <[email protected]> wrote: > > > On Thu, Mar 31, 2011 at 3:54 AM, Alan Cox <[email protected]> > > wrote: > > > On Wed, 30 Mar 2011 23:09:54 +0800 > > > Feng Tang <[email protected]> wrote: > > > > > >> From: Alek Du <[email protected]> > > >> > > >> Current poll transfer will read/write one word, then wait till the > > >> hw is non-busy, it's not efficient. This patch will try to > > >> read/write as many words as permitted by hardware FIFO depth. > > > > > > This is reported to cause a regression on internal testing. It's > > > one of that set of changes which seems to be breaking the > > > touchscreen. > > > > > > Should we get that resolved before these go upstream ? > > > > If this has a known/suspected regression, then I would say yes. I've > > got it queued for 2.6.40, but I can easily drop it. > > I did some investigation about the regression, it's about a spi touch > screen, which needs some delay between every word of read/write, it works > with old dw_spi driver, whose basic PIO working model is waiting till hw > is not busy for every word operation. > > With this optimization, the dw spi driver will try to feed the FIFO as > much as possible. If we enforce the delay in that touch screen driver, > it works again. > > So I would say, this patch should be ok to get merged. Thanks Feng. I agree this issue is due to the poor timing control in this touch screen driver. The SPI layer should do transfer as fast as possible. Alek > > Thanks, > Feng > > > > > g. ------------------------------------------------------------------------------ Fulfilling the Lean Software Promise Lean software platforms are now widely adopted and the benefits have been demonstrated beyond question. Learn why your peers are replacing JEE containers with lightweight application servers - and what you can gain from the move. http://p.sf.net/sfu/vmware-sfemails _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
