Hi, We had a problem with beaglebone black's HDMI output, where setting some clock rates to the display PLL failed oddly. The main issue was that the dpll code doesn't actually try to round the given rate, it only finds exact matches. That is what these patches fix (well, the second patch). However, there is another issue, which made finding and debugging this a bit difficult. When the dpll round_rate failed, it returned ~0 as a rate. However, drivers/clk/clk-divider.c, which called the round_rate, didn't realize that is an error value, and so didn't fail but proceeded, which didn't lead to anything good. This series doesn't try to fix that other issue. There's also a third issue that I think happens more easily after this series is applied: there are no checks for maximum rate for the DPLLs. I think the maximum rate is generally 2GHz, but at least my BeagleBone Black refused to lock the display PLL with anything over 1.3GHz-1.4GHz. High PLL clock rates happen quite easily with a setup where there's a DPLL and an additional divider, handled by clk-divider.c. When the clk-divider.c is asked to provide a clock rate (that could be quite low), it'll try to find a good clock from its parent, the DPLL, that it can divide down to the requested clock. As the DPLL driver is only limited by its multiplier and divider register widths, it'll gladly offer 2GHz+ clocks, which eventually will fail as they can't be locked. So this series is only a partial fix for the clock issues. Also, while the board debugged was BB Black, I think the same code is used and thus the same issues are present on all (or most) omap2+ SoCs. Tomi Tomi Valkeinen (2): ARM: OMAP2+: fix rate prints ARM: OMAP2+: fix dpll round_rate() to actually round arch/arm/mach-omap2/clkt_dpll.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) -- 1.8.3.2 -- 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
