On pon, 2015-01-05 at 15:05 +0100, Linus Walleij wrote: > On Fri, Dec 5, 2014 at 12:00 PM, Krzysztof Kozlowski > <k.kozlowski@xxxxxxxxxxx> wrote: > > > The audio subsystem on Exynos 5420 has separate clocks and GPIO. To > > operate properly on GPIOs the main block clock 'mau_epll' must be > > enabled. > > > > This was observed on Peach Pi/Pit and Arndale Octa (after enabling i2s0) > > after introducing runtime PM to pl330 DMA driver. After that commit the > > 'mau_epll' was gated, because the "amba" clock was disabled and there > > were no more users of mau_epll. > > > > The system hang just before probing i2s0 because > > samsung_pinmux_setup() tried to access memory from audss block which was > > gated. > > > > Add a clock property to the pinctrl driver and enable the clock during > > GPIO setup. During normal GPIO operations (set, get, set_direction) the > > clock is not enabled. > > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> > > Tested-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx> > > Tomasz, is this OK and should I apply it for fixes or next? Ha! That is a good question. The issue is fixed for now by the workaround (merged) [1]. The workaround just enables the clock for entire runtime of Exynos 5420-like device. This has some energy impact - around 1.5% in idle [2]. So actually this is question which way we want to solve it: 1. Stick with the workaround (small piece of code, energy impact when not used). 2. Full clock enable on use (big chunk of code, no energy impact when not used). [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f1e9203e2366164b832d8a6ce10134de8c575178 [2] http://www.spinics.net/lists/linux-samsung-soc/msg39827.html Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
