On Fri, Jan 25, 2013 at 12:25:07PM -0800, Greg Kroah-Hartman wrote: > On Wed, Jan 23, 2013 at 02:07:57PM +0900, Chanho Min wrote: > > On Tue, Jan 22, 2013 at 10:18 PM, Linus Walleij > > <linus.walleij@xxxxxxxxxx> wrote: > > >> - If poll timer is activated, We use consistent DMA mappings to avoid from > > >> the frequent cache operation of the timer function. sg->coherency is used > > >> to check if buffer is coherent. > > > > > > Hm. We can begin like this but maybe we should later patch it to > > > make this the default unless it has performance impacts on our > > > systems. > > Good, I really hope to make this the default. > > We expect it has no impact to system even if no polling use. > > > > > Maybe this is a good opportunity to add some kerneldoc above > > > this struct so as to help platform implementers. It will invariably > > > be reused by Device Tree binding authors later on... > > Agree, but, frankly I need help about what I didn't modify. > > So We will leave this work for the next submit. > > So, should this patch be applied? Can I get an ack from someone who > knows this driver/platform please? Well, I thought I had explained that I'd prefer to see the poll rate adjusted with the baud rate, but maybe I wasn't explicit enough. Instead, what we seem to have ended up with are two new entries in platform data (which we're trying to get away from with DT): + unsigned int dma_rx_poll_rate; + unsigned int dma_rx_poll_timeout; If this were to be done, then receive DMA could be used on the Versatile PB platforms without having it suck CPU usage unnecessarily at slower baud rates. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
