Hello Tomi, On Mon, 14 May 2012, Tomi Valkeinen wrote: > I've been doing testing to understand the problem, but so far I don't > have any idea why things go wrong. I haven't found out any logic in > which configuration works and which doesn't. Looks to me that for some > reason the PM prevents DSS from getting data fast enough with certain > fifo thresholds. > > I have two ways to avoid the problem, but I've been reluctant to make > patches for those because I feel it's just hiding the problem. One way > is to change DISPC SIDLEMODE or MIDLEMODE to disallow idle/standby. The > other is to use certain fifo threshold values, which just seem to work > for unknown reasons. > > Considering that we already have a SIDLEMODE hack in DSS for omap3 when > using DSI, I wonder if the omap3 PM + DSS combination is just plain > broken, and we should disallow idle. I'm not quite sure what are the > implications of that. > > I'd appreciate comments from the PM people =). This may be caused by one of the DPLLs going into autoidle. This can involve a significant wakeup latency. I'd suggest looking at DPLL3, which provides the DSS interface clock, and DPLL4, which can provide the DSS functional clock. Could you try: 1. applying something like the patch at the bottom of this message and seeing if it makes any difference? 2. if #1 does not work, changing the "dpll3" in the patch to "dpll4" ? 3. if #2 does not work, disabling autoidle on both dpll3 and dpll4? I regret that I haven't been able to focus more on DSS issues - - Paul Date: Wed, 14 Mar 2012 17:49:43 -0600 (MDT) From: Paul Walmsley <paul@xxxxxxxxx> Subject: Patch that should disable DPLL3 autoidle Test patch to disable DPLL3 autoidle. --- arch/arm/plat-omap/clock.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c index 567e4b5..4b02b35 100644 --- a/arch/arm/plat-omap/clock.c +++ b/arch/arm/plat-omap/clock.c @@ -351,6 +351,13 @@ int omap_clk_enable_autoidle_all(void) if (c->ops->allow_idle) c->ops->allow_idle(c); + c = clk_get(NULL, "dpll3_ck"); + if (c && c->ops->deny_idle) + c->ops->deny_idle(c); + else + WARN(1, "Cannot disable autoidle on DPLL3\n"); + clk_put(c); + spin_unlock_irqrestore(&clockfw_lock, flags); return 0; -- 1.7.9.1 -- 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
