9429b12dfc
[ Upstream commit 8df1ddb5bf11ab820ad991e164dab82c0960add9 ] If an eDP panel is not powered on then any attempts to talk to it over the DP AUX channel will timeout. Unfortunately these attempts may be quite slow. Userspace can initiate these attempts either via a /dev/drm_dp_auxN device or via the created i2c device. Making the DP AUX drivers timeout faster is a difficult proposition. In theory we could just poll the panel's HPD line in the AUX transfer function and immediately return an error there. However, this is easier said than done. For one thing, there's no hard requirement to hook the HPD line up for eDP panels and it's OK to just delay a fixed amount. For another thing, the HPD line may not be fast to probe. On parade-ps8640 we need to wait for the bridge chip's firmware to boot before we can get the HPD line and this is a slow process. The fact that the transfers are taking so long to timeout is causing real problems. The open source fwupd daemon sometimes scans DP busses looking for devices whose firmware need updating. If it happens to scan while a panel is turned off this scan can take a long time. The fwupd daemon could try to be smarter and only scan when eDP panels are turned on, but we can also improve the behavior in the kernel. Let's let eDP panels drivers specify that a panel is turned off and then modify the common AUX transfer code not to attempt a transfer in this case. Tested-by: Steev Klimaszewski <steev@kali.org> Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org> Tested-by: Eizan Miyamoto <eizan@chromium.org> Acked-by: Neil Armstrong <neil.armstrong@linaro.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240202141109.1.I24277520ac754ea538c9b14578edc94e1df11b48@changeid Stable-dep-of: 5e842d55bad7 ("drm/panel: atna33xc20: Fix unbalanced regulator in the case HPD doesn't assert") Signed-off-by: Sasha Levin <sashal@kernel.org> |
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| .. | ||
| drm_dp.h | ||
| drm_dp_aux_bus.h | ||
| drm_dp_dual_mode_helper.h | ||
| drm_dp_helper.h | ||
| drm_dp_mst_helper.h | ||
| drm_dsc.h | ||
| drm_dsc_helper.h | ||
| drm_hdcp.h | ||
| drm_hdcp_helper.h | ||
| drm_hdmi_helper.h | ||
| drm_scdc.h | ||
| drm_scdc_helper.h | ||