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5978118c39
The current code only runs when we do an I915_WRITE operation. It
checks if the unclaimed register flag is set before we do the
operation, and then it checks it again after we do the operation. This
double check allows us to find out if the I915_WRITE operation in
question is the bad one, or if some previous code is the bad one. When
it finds a problem, our code uses DRM_ERROR to signal it.
The good thing about the current code is that it detects the problem,
so at least we can know we did something wrong. The problem is that
even though we find the problem, we don't really have much information
to actually debug it. So whenever I see one of these DRM_ERROR
messages on my systems, the first thing I do is apply a patch to
change the DRM_ERROR to a WARN and also check for unclaimed registers
on I915_READ operations. This local patch makes things even slower,
but it usually helps a lot in finding the bad code.
The first point here is that since the current code is only useful to
detect whether we have a problem or not, but it is not really good to
find the cause of the problem, I don't think we should be checking
both before and after every I915_WRITE operation: just doing the check
once should be enough for us to quickly detect problems. With this
change, the code that runs by default for every single user will only
do 1 read operation for every single I915_WRITE, instead of 2. This
patch does this change.
The second point is that the local patch I have should be upstream,
but since it makes things slower it should be disabled by default. So
I added the i915.mmio_debug option to enable it.
So after this patch, this is what will happen:
- By default, we will try to detect unclaimed registers once after
every I915_WRITE operation. Previously we tried twice for every
I915_WRITE.
- When we find an unclaimed register we will still print a DRM_ERROR
message, but we will now tell the user to try again with
i915.mmio_debug=1.
- When we use i915.mmio_debug=1 we will try to find unclaimed
registers both before and after every I915_READ and I915_WRITE
operation, and we will print stack traces in case we find them.
This should really help locating the exact point of the bad code
(or at least finding out that i915.ko is not the problem).
This commit also opens space for really-slow register debugging
operations on other platforms. In theory we can now add lots and lots
of debug code behind i915.mmio_debug, enable this option on our tests,
and catch more problems.
v2: - Remove not-so-useful comments (Daniel)
- Fix the param definition macros (Rodrigo)
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
170 lines
6.5 KiB
C
170 lines
6.5 KiB
C
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "i915_drv.h"
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struct i915_params i915 __read_mostly = {
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.modeset = -1,
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.panel_ignore_lid = 1,
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.powersave = 1,
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.semaphores = -1,
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.lvds_downclock = 0,
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.lvds_channel_mode = 0,
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.panel_use_ssc = -1,
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.vbt_sdvo_panel_type = -1,
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.enable_rc6 = -1,
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.enable_fbc = -1,
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.enable_hangcheck = true,
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.enable_ppgtt = -1,
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.enable_psr = 1,
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.preliminary_hw_support = IS_ENABLED(CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT),
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.disable_power_well = 1,
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.enable_ips = 1,
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.fastboot = 0,
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.prefault_disable = 0,
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.reset = true,
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.invert_brightness = 0,
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.disable_display = 0,
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.enable_cmd_parser = 1,
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.disable_vtd_wa = 0,
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.use_mmio_flip = 0,
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.mmio_debug = 0,
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};
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module_param_named(modeset, i915.modeset, int, 0400);
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MODULE_PARM_DESC(modeset,
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"Use kernel modesetting [KMS] (0=DRM_I915_KMS from .config, "
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"1=on, -1=force vga console preference [default])");
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module_param_named(panel_ignore_lid, i915.panel_ignore_lid, int, 0600);
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MODULE_PARM_DESC(panel_ignore_lid,
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"Override lid status (0=autodetect, 1=autodetect disabled [default], "
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"-1=force lid closed, -2=force lid open)");
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module_param_named(powersave, i915.powersave, int, 0600);
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MODULE_PARM_DESC(powersave,
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"Enable powersavings, fbc, downclocking, etc. (default: true)");
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module_param_named(semaphores, i915.semaphores, int, 0400);
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MODULE_PARM_DESC(semaphores,
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"Use semaphores for inter-ring sync "
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"(default: -1 (use per-chip defaults))");
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module_param_named(enable_rc6, i915.enable_rc6, int, 0400);
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MODULE_PARM_DESC(enable_rc6,
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"Enable power-saving render C-state 6. "
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"Different stages can be selected via bitmask values "
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"(0 = disable; 1 = enable rc6; 2 = enable deep rc6; 4 = enable deepest rc6). "
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"For example, 3 would enable rc6 and deep rc6, and 7 would enable everything. "
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"default: -1 (use per-chip default)");
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module_param_named(enable_fbc, i915.enable_fbc, int, 0600);
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MODULE_PARM_DESC(enable_fbc,
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"Enable frame buffer compression for power savings "
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"(default: -1 (use per-chip default))");
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module_param_named(lvds_downclock, i915.lvds_downclock, int, 0400);
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MODULE_PARM_DESC(lvds_downclock,
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"Use panel (LVDS/eDP) downclocking for power savings "
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"(default: false)");
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module_param_named(lvds_channel_mode, i915.lvds_channel_mode, int, 0600);
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MODULE_PARM_DESC(lvds_channel_mode,
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"Specify LVDS channel mode "
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"(0=probe BIOS [default], 1=single-channel, 2=dual-channel)");
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module_param_named(lvds_use_ssc, i915.panel_use_ssc, int, 0600);
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MODULE_PARM_DESC(lvds_use_ssc,
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"Use Spread Spectrum Clock with panels [LVDS/eDP] "
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"(default: auto from VBT)");
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module_param_named(vbt_sdvo_panel_type, i915.vbt_sdvo_panel_type, int, 0600);
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MODULE_PARM_DESC(vbt_sdvo_panel_type,
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"Override/Ignore selection of SDVO panel mode in the VBT "
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"(-2=ignore, -1=auto [default], index in VBT BIOS table)");
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module_param_named(reset, i915.reset, bool, 0600);
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MODULE_PARM_DESC(reset, "Attempt GPU resets (default: true)");
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module_param_named(enable_hangcheck, i915.enable_hangcheck, bool, 0644);
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MODULE_PARM_DESC(enable_hangcheck,
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"Periodically check GPU activity for detecting hangs. "
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"WARNING: Disabling this can cause system wide hangs. "
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"(default: true)");
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module_param_named(enable_ppgtt, i915.enable_ppgtt, int, 0400);
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MODULE_PARM_DESC(enable_ppgtt,
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"Override PPGTT usage. "
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"(-1=auto [default], 0=disabled, 1=aliasing, 2=full)");
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module_param_named(enable_psr, i915.enable_psr, int, 0600);
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MODULE_PARM_DESC(enable_psr, "Enable PSR (default: true)");
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module_param_named(preliminary_hw_support, i915.preliminary_hw_support, int, 0600);
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MODULE_PARM_DESC(preliminary_hw_support,
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"Enable preliminary hardware support.");
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module_param_named(disable_power_well, i915.disable_power_well, int, 0600);
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MODULE_PARM_DESC(disable_power_well,
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"Disable the power well when possible (default: true)");
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module_param_named(enable_ips, i915.enable_ips, int, 0600);
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MODULE_PARM_DESC(enable_ips, "Enable IPS (default: true)");
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module_param_named(fastboot, i915.fastboot, bool, 0600);
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MODULE_PARM_DESC(fastboot,
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"Try to skip unnecessary mode sets at boot time (default: false)");
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module_param_named(prefault_disable, i915.prefault_disable, bool, 0600);
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MODULE_PARM_DESC(prefault_disable,
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"Disable page prefaulting for pread/pwrite/reloc (default:false). "
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"For developers only.");
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module_param_named(invert_brightness, i915.invert_brightness, int, 0600);
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MODULE_PARM_DESC(invert_brightness,
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"Invert backlight brightness "
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"(-1 force normal, 0 machine defaults, 1 force inversion), please "
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"report PCI device ID, subsystem vendor and subsystem device ID "
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"to dri-devel@lists.freedesktop.org, if your machine needs it. "
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"It will then be included in an upcoming module version.");
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module_param_named(disable_display, i915.disable_display, bool, 0600);
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MODULE_PARM_DESC(disable_display, "Disable display (default: false)");
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module_param_named(disable_vtd_wa, i915.disable_vtd_wa, bool, 0600);
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MODULE_PARM_DESC(disable_vtd_wa, "Disable all VT-d workarounds (default: false)");
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module_param_named(enable_cmd_parser, i915.enable_cmd_parser, int, 0600);
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MODULE_PARM_DESC(enable_cmd_parser,
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"Enable command parsing (1=enabled [default], 0=disabled)");
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module_param_named(use_mmio_flip, i915.use_mmio_flip, int, 0600);
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MODULE_PARM_DESC(use_mmio_flip,
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"use MMIO flips (-1=never, 0=driver discretion [default], 1=always)");
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module_param_named(mmio_debug, i915.mmio_debug, bool, 0600);
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MODULE_PARM_DESC(mmio_debug,
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"Enable the MMIO debug code (default: false). This may negatively "
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"affect performance.");
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