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Exynos SYSMMU (IOMMU) integration with DT and DMA-mapping subsystem

Joonyoung Shim linux-arm-kernel linux-iommu linux-samsung-soc 7 versions – New

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  1. v3 Latest posting 7/70 of 19 patches 0 repliesNew
  2. v3 posting 6/70 of 19 patches 0 repliesSuperseded
  3. v3 posting 5/70 of 19 patches 0 repliesSuperseded
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v3 posting 4/70 of 19 patches0 repliesSuperseded
v3 posting 3/70 of 19 patches0 repliesSuperseded
v3 posting 2/70 of 19 patches0 repliesSuperseded
v3 posting 1/70 of 19 patches0 repliesSuperseded

Patches in v3 posting 7/7 No applies recorded yet

None of the 19 patches the cover letter announces are in this archive.

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Read the v3 thread

Cover letter [PATCH v3 00/19] Exynos SYSMMU (IOMMU) integration with DT and DMA-mapping subsystem

Hi,

Quoted 6 lines · Javier Martinez Canillas
Quoted 5 lines · Javier Martinez Canillas

I dug further on this issue and found that the cause is that the exynos_mixer driver needs some clocks (CLK_HDMI and CLK_SCLK_HDMI) grabbed by exynos_hdmi to be kept enabled after hdmi_poweroff (drivers/gpu/drm/exynos/exynos_hdmi.c).

Quoted 7 lines
Quoted 7 lines

Otherwise, any access to mixer device registers leads to an imprecise external abort error. The following change [0] to the Exynos DRM HDMI driver makes the issue to not happen and I can successfully execute:

# echo 1 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
# echo 0 > /sys/devices/platform/exynos-drm/graphics/fb0/blank

Did you execute this operation repeatedly? Still i get error when i execute this more than twice with your change [0].

Thanks.

Quoted 18 lines
Quoted 4 lines

Only not disabling the hdmi clock [1]: is enough but doing so makes sometimes the DISP1 power domain disabling fails. It doesn't seem to have side effect though since I also see the signal in the HDMI display to go standby and then on again.

Quoted 8 lines
# echo 0 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
# echo 1 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
[   63.089080] Power domain disp1-power-domain disable failed
# echo 0 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
#

That error message when both clocks are not disabled on hdmi_poweroff() though.

This should be: "That error message is not shown when both clocks are disabled".

Best regards,
Javier

Read the cover letter in its thread