On Tue, 04 Mar 2025, Mohammed Thasleem <mohammed.thasleem@xxxxxxxxx> wrote:
> Starting from MTL we don't have a platform agnostic way to validate
> DC6 state due to dc6 counter has been removed to validate DC state.
>
> The goal is to validate that the display HW can reach the DC6 power
> state. There is no HW DC6 residency counter (and there wasn't such
> a counter earlier either), so an alternative way is required. According
> to the HW team the display driver has programmed everything correctly in
> order to allow the DC6 power state if the DC5 power state is reached
> (indicated by the HW DC5 residency counter incrementing) and DC6 is
> enabled by the driver.
>
> Driver could take a snapshot of the DC5 residency counter right
> after it enables DC6 (dc5_residency_start) and increment the SW
> DC6 residency counter right before it disables DC6 or when user space
> reads the DC6 counter. So the driver would update the counter at these
> two points in the following way:
> dc6_residency_counter += dc5_current_count - dc5_start_count
>
> v2: Update the discription. (Imre)
> Read dc5 count during dc6 enable and disable then and update
> dc6 residency counter. (Imre)
> Remove variable from dmc structure. (Jani)
> Updated the subject title.
> v3: Add i915_power_domains lock to updated dc6 count in debugfs. (Imre)
> Use flags to check dc6 enable/disable states. (Imre)
> Move the display version check and counter read/update to
> a helper. (Imre)
> Resize the variable length. (Rodrigo)
> Use old dc6 debugfs entry for every platform. (Rodrigo)
>
> Signed-off-by: Mohammed Thasleem <mohammed.thasleem@xxxxxxxxx>
> ---
> .../gpu/drm/i915/display/intel_display_core.h | 2 ++
> .../i915/display/intel_display_power_well.c | 26 +++++++++++++++++++
> .../i915/display/intel_display_power_well.h | 1 +
> drivers/gpu/drm/i915/display/intel_dmc.c | 21 ++++++++++++---
> 4 files changed, 47 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
> index 554870d2494b..1608268bd9e2 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> @@ -490,6 +490,8 @@ struct intel_display {
>
> /* perform PHY state sanity checks? */
> bool chv_phy_assert[2];
> + unsigned int dc6_count;
> + unsigned int dc5_start_count;
> } power;
>
> struct {
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.c b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> index 5b60db597329..8478e687abb7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power_well.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power_well.c
> @@ -17,6 +17,7 @@
> #include "intel_dkl_phy.h"
> #include "intel_dkl_phy_regs.h"
> #include "intel_dmc.h"
> +#include "intel_dmc_regs.h"
I would prefer to avoid reading DMC registers in
intel_display_power_well.c. It's intel_dmc.c that's supposed to abstract
all things DMC.
> #include "intel_dmc_wl.h"
> #include "intel_dp_aux_regs.h"
> #include "intel_dpio_phy.h"
> @@ -728,6 +729,22 @@ void gen9_sanitize_dc_state(struct intel_display *display)
> power_domains->dc_state = val;
> }
>
> +void update_dc6_count(struct intel_display *display, bool dc6_en_dis)
As a rule of thumb, functions in file intel_foo.c should be named
intel_foo_something().
What does dc6_en_dis mean? Please name it such that it's understandable.
> +{
> + u32 dc5_cur_count;
> +
> + if (DISPLAY_VER(display) < 14)
> + return;
> +
> + dc5_cur_count = intel_de_read(display, DG1_DMC_DEBUG_DC5_COUNT);
> +
> + if (dc6_en_dis) {
> + display->power.dc6_count += dc5_cur_count - display->power.dc5_start_count;
> + display->power.dc5_start_count = dc5_cur_count;
> + } else
> + display->power.dc5_start_count = dc5_cur_count;
> +}
> +
> /**
> * gen9_set_dc_state - set target display C power state
> * @display: display instance
> @@ -756,6 +773,7 @@ void gen9_set_dc_state(struct intel_display *display, u32 state)
> struct i915_power_domains *power_domains = &display->power.domains;
> u32 val;
> u32 mask;
> + bool dc6_was_enabled, enable_dc6;
>
> if (!HAS_DISPLAY(display))
> return;
> @@ -774,11 +792,19 @@ void gen9_set_dc_state(struct intel_display *display, u32 state)
> drm_err(display->drm, "DC state mismatch (0x%x -> 0x%x)\n",
> power_domains->dc_state, val & mask);
>
> + enable_dc6 = state & DC_STATE_EN_UPTO_DC6;
> + dc6_was_enabled = val & DC_STATE_EN_UPTO_DC6;
> + if (!dc6_was_enabled && enable_dc6)
> + update_dc6_count(display, false);
> +
> val &= ~mask;
> val |= state;
>
> gen9_write_dc_state(display, val);
>
> + if (!enable_dc6)
> + update_dc6_count(display, true);
> +
> power_domains->dc_state = val & mask;
> }
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power_well.h b/drivers/gpu/drm/i915/display/intel_display_power_well.h
> index ec8e508d0593..54fff1f888b4 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power_well.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_power_well.h
> @@ -161,6 +161,7 @@ void gen9_set_dc_state(struct intel_display *display, u32 state);
> void gen9_disable_dc_states(struct intel_display *display);
> void bxt_enable_dc9(struct intel_display *display);
> void bxt_disable_dc9(struct intel_display *display);
> +void update_dc6_count(struct intel_display *display, bool dc6_en_dis);
>
> extern const struct i915_power_well_ops i9xx_always_on_power_well_ops;
> extern const struct i915_power_well_ops chv_pipe_power_well_ops;
> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
> index fa6944e55d95..4cbc54a97655 100644
> --- a/drivers/gpu/drm/i915/display/intel_dmc.c
> +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
> @@ -28,10 +28,12 @@
> #include "i915_drv.h"
> #include "i915_reg.h"
> #include "intel_de.h"
> +#include "intel_display_power_well.h"
> #include "intel_dmc.h"
> #include "intel_dmc_regs.h"
> #include "intel_step.h"
>
> +
> /**
> * DOC: DMC Firmware Support
> *
> @@ -1237,8 +1239,10 @@ static int intel_dmc_debugfs_status_show(struct seq_file *m, void *unused)
> struct intel_display *display = m->private;
> struct drm_i915_private *i915 = to_i915(display->drm);
> struct intel_dmc *dmc = display_to_dmc(display);
> + struct i915_power_domains *power_domains = &display->power.domains;
> intel_wakeref_t wakeref;
> i915_reg_t dc5_reg, dc6_reg = INVALID_MMIO_REG;
> + u32 dc6_was_enabled;
This is used as a bool, the name sounds like a bool, please make it a
bool. It could also be moved to tighter scope below.
Also, what do you mean "was enabled"? Isn't it "is enabled"? Or just
"dc6_enabled"?
>
> if (!HAS_DMC(display))
> return -ENODEV;
> @@ -1287,9 +1291,20 @@ static int intel_dmc_debugfs_status_show(struct seq_file *m, void *unused)
> }
>
> seq_printf(m, "DC3 -> DC5 count: %d\n", intel_de_read(display, dc5_reg));
> - if (i915_mmio_reg_valid(dc6_reg))
> - seq_printf(m, "DC5 -> DC6 count: %d\n",
> - intel_de_read(display, dc6_reg));
> +
> + if (DISPLAY_VER(display) >= 14) {
> + dc6_was_enabled = DC_STATE_EN_UPTO_DC6 &
> + intel_de_read(display, DC_STATE_EN);
> + if (dc6_was_enabled) {
> + mutex_lock(&power_domains->lock);
> + update_dc6_count(display, true);
> + mutex_unlock(&power_domains->lock);
> + }
> + } else
> + display->power.dc6_count = i915_mmio_reg_valid(dc6_reg) ?
> + intel_de_read(display, dc6_reg) : 0;
I think the whole division of responsibilities between
intel_display_power.c and intel_dmc.c is messed up here. You add a
function update_dc6_count() that updates the new members you added, but
then you also read DMC registers there *and* update the field here
too. Please consider who does what, and devise the interfaces such that
they respect the boundaries.
If one arm of an if requires braces, then all of them do.
> +
> + seq_printf(m, "DC5 -> DC6 count: %d\n", display->power.dc6_count);
This now starts always printing zero for !i915_mmio_reg_valid(dc6_reg)
&& display < 14, while previously it was not printed at all.
>
> seq_printf(m, "program base: 0x%08x\n",
> intel_de_read(display, DMC_PROGRAM(dmc->dmc_info[DMC_FW_MAIN].start_mmioaddr, 0)));
--
Jani Nikula, Intel
