Some display MMIO transactions for offsets in the range that requires
the DMC wakelock happen in atomic context (this has been confirmed
during tests on PTL). That means that we need to use a non-sleeping
variant of MMIO waiting function.
Implement __intel_de_wait_for_register_atomic_nowl() and use it when
waiting for acknowledgment of acquire/release.
v2:
- No __intel_de_wait_for_register_atomic_nowl() wrapper to convert
i915 to display. (Jani)
- Add a quick explanation why DMC_WAKELOCK_CTL_TIMEOUT_US is defined
in microseconds. (Luca)
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241108130218.24125-4-gustavo.sousa@intel.com
We need to be able to do both MMIO and DSB based pipe/plane
programming. To that end plumb the 'dsb' all way from the top
into the plane commit hooks.
The compiler appears smart enough to combine the branches from
all the back-to-back register writes into a single branch.
So the generated asm ends up looking more or less like this:
plane_hook()
{
if (dsb) {
intel_dsb_reg_write();
intel_dsb_reg_write();
...
} else {
intel_de_write_fw();
intel_de_write_fw();
...
}
}
which seems like a reasonably efficient way to do this.
An alternative I was also considering is some kind of closure
(register write function + display vs. dsb pointer passed to it).
That does result is smaller code as there are no branches anymore,
but having each register access go via function pointer sounds
less efficient.
Not that I actually measured the overhead of either approach yet.
Also the reg_rw tracepoint seems to be making a huge mess of the
generated code for the mmio path. And additionally there's some
kind of IS_GSI_REG() hack in __raw_uncore_read() which ends up
generating a pointless branch for every mmio register access.
So looks like there might be quite a bit of room for improvement
in the mmio path still.
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-12-ville.syrjala@linux.intel.com
In order to reduce the DC5->DC2 restore time, wakelocks have been
introduced in DMC so the driver can tell it when registers and other
memory areas are going to be accessed and keep their respective blocks
awake.
Implement this in the driver by adding the concept of DMC wakelocks.
When the driver needs to access memory which lies inside pre-defined
ranges, it will tell DMC to set the wakelock, access the memory, then
wait for a while and clear the wakelock.
The wakelock state is protected in the driver with spinlocks to
prevent concurrency issues.
BSpec: 71583
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412094148.808179-2-luciano.coelho@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Several of our i915 header files, have been including i915_reg.h. This
means that any change to i915_reg.h will trigger a full rebuild of
pretty much every file of the driver, even those that don't have any
kind of register access. Let's delete the i915_reg.h include from all
headers and add an explicit include from the .c files that truly
need the register definitions; those that need a definition of
i915_reg_t for a function definition can get it from i915_reg_defs.h
instead.
We also remove two non-register #define's (VLV_DISPLAY_BASE and
GEN12_SFC_DONE_MAX) into i915_reg_defs.h to allow us to drop the
i915_reg.h include from a couple of headers.
There's probably a lot more header dependency optimization possible, but
the changes here roughly cut the number of files compiled after 'touch
i915_reg.h' in half --- a good first step.
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220127234334.4016964-7-matthew.d.roper@intel.com
We lost the i915_reg_rw tracepoint for a lot of display registers
when we switched from the heavyweight normal register accessors to
the lightweight _fw() variants. See eg. commit dd584fc071
("drm/i915: Use I915_READ_FW for plane updates").
Put the tracepoints back so that the register traces might
actually be useful. Hopefully these should be close to free
when the tracepoint is not enabled and thus not slow down
our vblank critical sections significantly.
v2: Copy paste the same-cacheline-hang warning from
intel_uncore.h (Anshuman)
Cc: Cooper Chiou <cooper.chiou@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210430143945.6776-2-ville.syrjala@linux.intel.com
