[Adding Inki and Joonyoung to cc list] Hello Marek, On Mon, Jan 19, 2015 at 5:30 PM, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote: >> >> The board instantly died then. No kernel log output from the serial >> console, the heartbeat just stops and the board is dead. Need to >> power-cycle to get it running again. >> >> I'm unsure how to triage this at all. > > > Thanks for you tests and pointing this issue. I turned out that the initial > fix proposed > by Andrzej Hajda > (http://www.spinics.net/lists/linux-samsung-soc/msg38915.html) worked > fine, while the final version merged to clock fixes ('clk: samsung: exynos4: > set parent > of sclk_hdmiphy to hdmi' - commit df019a5c0f7083001cb694f44821ca506425bda2) > doesn't work > properly. > I was working on adding HDMI support for Exynos5420/5422/5800 and I also found that the hdmi clock being gated by the exynos_hdmi driver on hdmi_poweroff(), was causing a system hang when the exynos_mixer driver tried to access the mixer module registers. My first approach was to do the same than Andrzej's patch, that is set the parent of mixer gate clock to hdmi so when the exynos_mixer driver enables its mixer clock, the hdmi clock would be enabled too. Unfortunately that didn't work (more on that below) > Please check the following kernel tree - instead of hacking around hdmi > clock I've added > handling of it directly to drm mixer driver: > https://git.linaro.org/people/marek.szyprowski/linux-srpol.git/shortlog/refs/heads/v3.19-odroid-hdmi > I hope that this will finally solve all mixer initialization related issues My second approach was indeed the same that you are doing, to add a phandle to the hdmi clock directly in the exynos_mixer driver to avoid having to set the parent of the mixer clock on each exynos clock driver. When dumping the value of the CLK_GATE_IP_DISP1 register I see that both CLK_HDMI and CLK_MIXER are set with both approaches but the system still crashes. So enabling the hdmi clock seems to be enough to make the mixer happy on Exynos4 but unfortunately is not enough on Exynos5420. > (also for > Odroid XU3, discussed recently in the other thread). If it works fine, I > will resend > exynos4 hdmi patches to include this change. > > I compared the clock hierarchy when the system is able to turn on and off the fb blank and when it crash and I notice this difference: Working: sclk_pwi 0 0 24000000 0 0 sclk_hdmiphy 1 1 24000000 0 0 mout_hdmi 1 1 24000000 0 0 sclk_hdmi 1 1 24000000 0 0 ... mout_pixel 0 0 24000000 0 0 dout_hdmi_pixel 0 0 24000000 0 0 sclk_pixel 0 0 24000000 0 0 Not working: sclk_pwi 0 0 24000000 0 0 sclk_hdmiphy 0 0 24000000 0 0 ... mout_pixel 0 0 24000000 0 0 dout_hdmi_pixel 0 0 24000000 0 0 mout_hdmi 0 0 24000000 0 0 sclk_hdmi 0 0 24000000 0 0 sclk_pixel 0 0 24000000 0 0 The difference is because the source clock of the hdmi clock is generated by the output of a mux clock (mout_hdmi) that select either dout_hdmi_pixel or sclk_hdmiphy as input parent. The exynos5420 clk driver defines as: PNAME(mout_hdmi_p) = {"dout_hdmi_pixel", "sclk_hdmiphy"}; ... MUX(CLK_MOUT_HDMI, "mout_hdmi", mout_hdmi_p, SRC_DISP10, 28, 1), And the exynos_hdmi driver does: clk_disable_unprepare(hdata->res.sclk_hdmi); clk_set_parent(hdata->res.mout_hdmi, hdata->res.sclk_hdmiphy); clk_prepare_enable(hdata->res.sclk_hdmi); So is not only that the hdmi clock has to be enabled but also the clock hierarchy matters. I don't even know if the hdmi clock is needed or is that enabling this clock has the side effect of enabling another clock in the hierarchy that is the one that is needed. It would be good if someone can compare the clock hierarchy on an Exynos4. So I would like to understand what is really the root cause here instead of trying to only solve the symptoms for each platform. I have also noticed this patch from Inki - commit 245f98f269714 ("drm/exynos: hdmi: fix power order issue") that forces the exynos_mixer to be disabled before exynos_hdmi to prevent a system crash but only for DRM_MODE_DPMS_OFF. So I wonder if the same should be true for DRM_MODE_DPMS_ON and the exynos_hdmi should be enabled before exynos_hdmi. IOW, I would like to know what is the dependency between the mixer and hdmi modules at the module level first and then once that is clear we can dig deeper on what clocks are needed and when those must be enabled. Best regards, Javier -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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