On Fri, Feb 21, 2025 at 08:35:00PM +0200, Imre Deak wrote:
> On Wed, Feb 12, 2025 at 05:19:35PM +0530, Mohammed Thasleem 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.
> >
> > Signed-off-by: Mohammed Thasleem <mohammed.thasleem@xxxxxxxxx>
> > ---
> > .../gpu/drm/i915/display/intel_display_core.h | 2 ++
> > .../i915/display/intel_display_power_well.c | 20 ++++++++++++++++++-
> > drivers/gpu/drm/i915/display/intel_dmc.c | 14 ++++++++++---
> > 3 files changed, 32 insertions(+), 4 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..0a1e3dc2804f 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_residency_counter;
> > + 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 f45a4f9ba23c..cfa53ee84323 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"
> > #include "intel_dmc_wl.h"
> > #include "intel_dp_aux_regs.h"
> > #include "intel_dpio_phy.h"
> > @@ -755,7 +756,7 @@ void gen9_sanitize_dc_state(struct intel_display *display)
> > void gen9_set_dc_state(struct intel_display *display, u32 state)
> > {
> > struct i915_power_domains *power_domains = &display->power.domains;
> > - u32 val;
> > + u32 val, dc5_current_count;
> > u32 mask;
> >
> > if (!HAS_DISPLAY(display))
> > @@ -775,11 +776,28 @@ 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);
> >
> > + if (DISPLAY_VER(display) >= 14) {
> > + /* If disabling DC6, update dc6_allowed counter */
> > + if (!(state & DC_STATE_EN_UPTO_DC6) && (val & DC_STATE_EN_UPTO_DC6)) {
> > + dc5_current_count = intel_de_read(display, DG1_DMC_DEBUG_DC5_COUNT);
> > + display->power.dc6_residency_counter += dc5_current_count - display->power.dc5_start_count;
> > + display->power.dc5_start_count = dc5_current_count;
>
> Would be clearer if you used
>
> enable_dc6 = state & DC_STATE_EN_UPTO_DC6
> dc6_was_enabled = val & DC_STATE_EN_UPTO_DC6
>
> flags and moved the display version check and counter read/update to a
> helper.
Also, the update above should happen after DC6 is disabled and the
update below should happen before DC6 is enabled.
> > + }
> > + }
> > +
> > val &= ~mask;
> > val |= state;
> >
> > gen9_write_dc_state(display, val);
> >
> > + if (DISPLAY_VER(display) >= 14) {
> > + /* If enabling DC6, store DC5 count */
> > + if ((state & DC_STATE_EN_UPTO_DC6)) {
> > + dc5_current_count = intel_de_read(display, DG1_DMC_DEBUG_DC5_COUNT);
> > + display->power.dc5_start_count = dc5_current_count;
> > + }
> > + }
>
> This could also be in a helper, calling it if !dc6_was_enabled && enable_dc6.
>
> > +
> > power_domains->dc_state = val & mask;
> > }
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c b/drivers/gpu/drm/i915/display/intel_dmc.c
> > index 221d3abda791..e4d3ce796c99 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dmc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
> > @@ -1242,6 +1242,7 @@ static int intel_dmc_debugfs_status_show(struct seq_file *m, void *unused)
> > struct intel_dmc *dmc = display_to_dmc(display);
> > intel_wakeref_t wakeref;
> > i915_reg_t dc5_reg, dc6_reg = INVALID_MMIO_REG;
> > + u32 dc5_current_count;
> >
> > if (!HAS_DMC(display))
> > return -ENODEV;
> > @@ -1290,9 +1291,16 @@ 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) {
> > + dc5_current_count = intel_de_read(display, dc5_reg);
> > + display->power.dc6_residency_counter += dc5_current_count - display->power.dc5_start_count;
>
>
> The above needs the i915_power_domains::lock, should be done only if DC6
> is enabled, and needs to also update display->power.dc5_start_count.
> This is the same update as you do in gen9_set_dc_state(), so could reuse
> the helper for that here.
>
> > + seq_printf(m, "DC6 Residency Counter: %d\n", display->power.dc6_residency_counter);
> > + } else {
> > + if (i915_mmio_reg_valid(dc6_reg))
> > + seq_printf(m, "DC5 -> DC6 count: %d\n",
> > + intel_de_read(display, dc6_reg));
> > + }
> >
> > seq_printf(m, "program base: 0x%08x\n",
> > intel_de_read(display, DMC_PROGRAM(dmc->dmc_info[DMC_FW_MAIN].start_mmioaddr, 0)));
> > --
> > 2.43.0
> >
