I don't think this is the cause of the interface freezes, but it still seems weird to me. In linux-5.4.y it is set to 2 (which should be the default according to "modinfo -p i915". Here is the relevant part of drivers/gpu/drm/i915/i915_params.h in linux-5.4 (which works perfectly):
#define I915_PARAMS_FOR_EACH(param) \
param(char *, vbt_firmware, NULL) \
param(int, modeset, -1) \
param(int, lvds_channel_mode, 0) \
param(int, panel_use_ssc, -1) \
param(int, vbt_sdvo_panel_type, -1) \
param(int, enable_dc, -1) \
param(int, enable_fbc, -1) \
param(int, enable_psr, -1) \
param(int, disable_power_well, -1) \
param(int, enable_ips, 1) \
param(int, invert_brightness, 0) \
param(int, enable_guc, 0) \
param(int, guc_log_level, -1) \
param(char *, guc_firmware_path, NULL) \
param(char *, huc_firmware_path, NULL) \
param(char *, dmc_firmware_path, NULL) \
param(int, mmio_debug, -IS_ENABLED(CONFIG_DRM_I915_DEBUG_MMIO)) \
param(int, edp_vswing, 0) \
param(int, reset, 2) \ //**** set to 2 ****
param(unsigned int, inject_load_failure, 0) \
param(int, fastboot, -1) \
param(int, enable_dpcd_backlight, 0) \
param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE) \
/* leave bools at the end to not create holes */ \
param(bool, alpha_support, IS_ENABLED(CONFIG_DRM_I915_ALPHA_SUPPORT)) \
param(bool, enable_hangcheck, true) \
param(bool, prefault_disable, false) \
param(bool, load_detect_test, false) \
param(bool, force_reset_modeset_test, false) \
param(bool, error_capture, true) \
param(bool, disable_display, false) \
param(bool, verbose_state_checks, true) \
param(bool, nuclear_pageflip, false) \
param(bool, enable_dp_mst, true) \
param(bool, enable_gvt, false)
in newer kernels it is set to 3 (and it also shows up as 3 in /sys/module/i915/parameters/reset):
#define I915_PARAMS_FOR_EACH(param) \
param(char *, vbt_firmware, NULL, 0400) \
param(int, modeset, -1, 0400) \
param(int, lvds_channel_mode, 0, 0400) \
param(int, panel_use_ssc, -1, 0600) \
param(int, vbt_sdvo_panel_type, -1, 0400) \
param(int, enable_dc, -1, 0400) \
param(int, enable_fbc, -1, 0600) \
param(int, enable_psr, -1, 0600) \
param(bool, psr_safest_params, false, 0400) \
param(bool, enable_psr2_sel_fetch, true, 0400) \
param(int, disable_power_well, -1, 0400) \
param(int, enable_ips, 1, 0600) \
param(int, invert_brightness, 0, 0600) \
param(int, enable_guc, -1, 0400) \
param(int, guc_log_level, -1, 0400) \
param(char *, guc_firmware_path, NULL, 0400) \
param(char *, huc_firmware_path, NULL, 0400) \
param(char *, dmc_firmware_path, NULL, 0400) \
param(bool, memtest, false, 0400) \
param(int, mmio_debug, -IS_ENABLED(CONFIG_DRM_I915_DEBUG_MMIO), 0600) \
param(int, edp_vswing, 0, 0400) \
param(unsigned int, reset, 3, 0600) \ //**** set to 3 ****
param(unsigned int, inject_probe_failure, 0, 0) \
param(int, fastboot, -1, 0600) \
param(int, enable_dpcd_backlight, -1, 0600) \
param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE, 0400) \
param(unsigned int, request_timeout_ms, CONFIG_DRM_I915_REQUEST_TIMEOUT, CONFIG_DRM_I915_REQUEST_TIMEOUT ? 0600 : 0) \
/* leave bools at the end to not create holes */ \
param(bool, enable_hangcheck, true, 0600) \
param(bool, load_detect_test, false, 0600) \
param(bool, force_reset_modeset_test, false, 0600) \
param(bool, error_capture, true, IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR) ? 0600 : 0) \
param(bool, disable_display, false, 0400) \
param(bool, verbose_state_checks, true, 0) \
param(bool, nuclear_pageflip, false, 0400) \
param(bool, enable_dp_mst, true, 0600) \
param(bool, enable_gvt, false, IS_ENABLED(CONFIG_DRM_I915_GVT) ? 0400 : 0)
If this is correct, "modinfo -p i915" ought to reflect the change, which seems to be undocumented. Patching the kernel, or using "i915.reset=2" boot param - the alleged default - has no effect (except setting /sys/module/i915/parameters/reset to 2; in any case the reset fails and the computer freezes). Maybe the setting is ignored - the driver is so messed-up that this doesn't seem unlikely.
Topic: Why is i915 reset param set to 3 (which is invalid) in recent linux kernels? (Read 696 times)
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