On Wed, Feb 08, 2012 at 10:59:06AM -0800, Tony Lindgren wrote: > * Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> [120208 08:10]: > > Commit 2fd149645eb4 (ARM: OMAP2+: UART: Remove omap_uart_can_sleep and add pm_qos) > > has caused a regression on OMAP3 platforms. > > > > When the UART is trying to transmit data, if we enter a low power mode, > > transmission stops, which makes serial on OMAP3 unusable - a 'dmesg' > > takes five minutes to be output at 115200 baud, at a rate of around a > > block of 16 characters every couple of seconds. > > > > Unfortunately, the commit above can't be reverted because of many other > > changes in this area, so this implements a dirty fix by disabling > > CPU idle in the places the original commit does, irrespective of the > > UART state. > ... > > > --- a/arch/arm/mach-omap2/pm34xx.c > > +++ b/arch/arm/mach-omap2/pm34xx.c > > @@ -421,7 +421,7 @@ static void omap3_pm_idle(void) > > local_irq_disable(); > > local_fiq_disable(); > > > > - if (omap_irq_pending() || need_resched()) > > + if (omap_irq_pending() || need_resched() || 1) > > goto out; > > > > trace_power_start(POWER_CSTATE, 1, smp_processor_id()); > > Argh, this is just too ugly. There has got to be a better fix for the > -rc series. That I'd agree on - because it is ugly and it's the best I could do to revert the commit mentioned above short of reverting a whole raft of other useful looking commits. There's got to be a better solution. > Looks like the patches to fix omap-serial.c are queued for v3.4, > so that won't help. Well, the fact of the matter is this is a regression, which means it needs fixing for v3.3. A simple patch would be preferred over more complex patches. So, if there's no other solution but to put the omap-serial patches in for v3.3, then that's the best solution for v3.3. First, someone who understands this code needs to see whether there is a simpler fix (eg, putting back what was there in a simpler form.) However, leaving it in its current state for v3.3 is not acceptable. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
