From: javier.martinez@collabora.co.uk (Javier Martinez Canillas) Date: Wed, 14 Jan 2015 01:24:01 +0100 Subject: [PATCH v3 00/19] Exynos SYSMMU (IOMMU) integration with DT and DMA-mapping subsystem In-Reply-To: <54B5B5F6.3030607@collabora.co.uk> References: <1416395748-10731-1-git-send-email-m.szyprowski@samsung.com> <1417514366.21830.22.camel@collabora.co.uk> <54818768.3080303@samsung.com> <54AC93E0.8010705@samsung.com> <54ACFD69.1020500@collabora.co.uk> <54AD0293.70909@samsung.com> <54AEB384.2040005@collabora.co.uk> <54B36C5A.6050109@samsung.com> <54B3F1B7.7090307@collabora.co.uk> <54B4ABFB.5000501@samsung.com> <54B5B5F6.3030607@collabora.co.uk> Message-ID: <54B5B721.4070309@collabora.co.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/14/2015 01:19 AM, Javier Martinez Canillas wrote: > > 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). > > 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 > > 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. > > # 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