Re: [PATCH 6/8] drm/i915/skl: Add DC6 Trigger sequence.

Imre Deak
2015-04-02T20:42:02Z

On Wed, 2015-04-01 at 16:22 +0530, Animesh Manna wrote:
> From: Suketu Shah <suketu.j.shah@intel.com>
>
> Add triggers for DC6 as per details provided in skl_enable_dc6
> and skl_disable_dc6 implementations.
>
> Also Call POSTING_READ for every write to a register to ensure
> it is written to immediately
>
> v1: Remove POSTING_READ and intel_prepare_ddi calls as they've been added in previous patches.
>
> v2:
> 1] Remove check for backlight disabled as it should be the case by that time.
> 2] Mark DC5 as disabled when enabling DC6.
> 3] Return from DC5-disabling function early if DC5 is already be disabled which can happen
> due to DC6-enabling earlier.
> 3] Ensure CSR firmware is loaded after resume from DC6 as corresponding memory contents won't
> be retained after runtime-suspend.
> 4] Ensure that CSR isn't identified as loaded before CSR-loading program is called during
> runtime-resume.
>
> v3: Rebase to latest
> Modified as per review comments from Imre and after discussion with Art:
> 1] DC6 should be preferably enabled when PG2 is disabled by SW as the check for PG1 being
> disabled is taken of by HW to enter DC6, and disabled when PG2 is enabled respectively.
> This helps save more power, especially in the case when display is disabled but GT is
> enabled. Accordingly, replacing DC5 trigger sequence with DC6 for SKL.
> 2] DC6 could be enabled from intel_runtime_suspend() function, if DC5 is already enabled.
> 3] Move CSR-load-status setting code from intel_runtime_suspend function to a new function.
>
> v4:
> 1] Enable/disable DC6 only when toggling the power-well using a newly defined macro ENABLE_DC6.
>
> v5:
> 1] Load CSR on system resume too as firmware may be lost on system suspend preventing
> enabling DC5, DC6.
> 2] DDI buffers shouldn't be programmed during driver-load/resume as it's already done
> during modeset initialization then and also that the encoder list is still uninitialized by
> then. Therefore, call intel_prepare_ddi function right after disabling DC6 but outside
> skl_disable_dc6 function and not during driver-load/resume.
>
> v6:
> 1] Rebase to latest.
> 2] Move SKL_ENABLE_DC6 macro definition from intel_display.c to intel_runtime_pm.c.
>
> v7:
> 1) Refactored the code for removing the warning got from checkpatch.
> 2) After adding dmc ver 1.0 support rebased on top of nightly. (Animesh)
>
> Issue: VIZ-2819
> Signed-off-by: A.Sunil Kamath <sunil.kamath@intel.com>
> Signed-off-by: Suketu Shah <suketu.j.shah@intel.com>
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 29 ++++++++++
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/intel_runtime_pm.c | 98 +++++++++++++++++----------------
> 3 files changed, 81 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 489caa6..352c7702 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -795,6 +795,8 @@ static int i915_drm_resume_early(struct drm_device *dev)
>
> if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
> hsw_disable_pc8(dev_priv);
> + else if (IS_SKYLAKE(dev_priv))
> + ret = skl_resume_prepare(dev_priv);
>
> intel_uncore_sanitize(dev);
> intel_power_domains_init_hw(dev_priv);
> @@ -1009,6 +1011,19 @@ static int i915_pm_resume(struct device *dev)
> return i915_drm_resume(drm_dev);
> }
>
> +static int skl_suspend_complete(struct drm_i915_private *dev_priv)
> +{
> + /* Enabling DC6 is not a hard requirement to enter runtime D3 */
> +
> + /*
> + * This is to ensure that CSR isn't identified as loaded before
> + * CSR-loading program is called during runtime-resume.
> + */
> + intel_csr_load_status_set(dev_priv, false);
> +
> + return 0;
> +}
> +
> static int hsw_suspend_complete(struct drm_i915_private *dev_priv)
> {
> hsw_enable_pc8(dev_priv);
> @@ -1016,6 +1031,16 @@ static int hsw_suspend_complete(struct drm_i915_private *dev_priv)
> return 0;
> }
>
> +int skl_resume_prepare(struct drm_i915_private *dev_priv)
> +{
> + struct drm_device *dev = dev_priv->dev;
> +
> + if (!intel_csr_load_status_get(dev_priv))

No need to check the above, it's guaranteed the firmware is not loaded
at this point.

> + intel_csr_load_program(dev);
> +
> + return 0;
> +}
> +
> /*
> * Save all Gunit registers that may be lost after a D3 and a subsequent
> * S0i[R123] transition. The list of registers needing a save/restore is
> @@ -1484,6 +1509,8 @@ static int intel_runtime_resume(struct device *device)
>
> if (IS_GEN6(dev_priv))
> intel_init_pch_refclk(dev);
> + else if (IS_SKYLAKE(dev))
> + ret = skl_resume_prepare(dev_priv);
> else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv))
> hsw_disable_pc8(dev_priv);
> else if (IS_VALLEYVIEW(dev_priv))
> @@ -1516,6 +1543,8 @@ static int intel_suspend_complete(struct drm_i915_private *dev_priv)
> struct drm_device *dev = dev_priv->dev;
> int ret;
>
> + if (IS_SKYLAKE(dev))
> + ret = skl_suspend_complete(dev_priv);
> if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> ret = hsw_suspend_complete(dev_priv);
> else if (IS_VALLEYVIEW(dev))
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3320fb4..5dd8d61 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2642,6 +2642,7 @@ extern void i915_update_gfx_val(struct drm_i915_private *dev_priv);
> int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool on);
> void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
> void i915_firmware_load_error_print(const char *fw_path, int err);
> +int skl_resume_prepare(struct drm_i915_private *dev_priv);

No need to export this, you can add a forward declaration at the top in
i915_drv.c.

>
> /* i915_irq.c */
> void i915_queue_hangcheck(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index dae65e0..cc94503 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -49,7 +49,8 @@
> * present for a given platform.
> */
>
> -#define GEN9_ENABLE_DC5(dev) (IS_SKYLAKE(dev))
> +#define GEN9_ENABLE_DC5(dev) 0
> +#define SKL_ENABLE_DC6(dev) IS_SKYLAKE(dev)
>
> #define for_each_power_well(i, power_well, domain_mask, power_domains) \
> for (i = 0; \
> @@ -373,7 +374,7 @@ static void assert_can_disable_dc5(struct drm_i915_private *dev_priv)
>
> WARN(!pg2_enabled, "PG2 not enabled to disable DC5.\n");
> WARN(dev_priv->pm.suspended,
> - "Disabling of DC5 while platform is runtime-suspended should never happen.\n");
> + "Platform is runtime-suspended, should not disable DC5.\n");
> }
>
> static void gen9_enable_dc5(struct drm_i915_private *dev_priv)
> @@ -438,8 +439,6 @@ static void skl_disable_dc6(struct drm_i915_private *dev_priv)
> val &= ~DC_STATE_EN_UPTO_DC6;
> I915_WRITE(DC_STATE_EN, val);
> POSTING_READ(DC_STATE_EN);
> -
> - intel_prepare_ddi(dev);
> }
>
> static void skl_set_power_well(struct drm_i915_private *dev_priv,
> @@ -483,55 +482,60 @@ static void skl_set_power_well(struct drm_i915_private *dev_priv,
> state_mask = SKL_POWER_WELL_STATE(power_well->data);
> is_enabled = tmp & state_mask;
>
> - if (enable) {
> - if (!enable_requested) {
> - WARN((tmp & state_mask) &&
> - !I915_READ(HSW_PWR_WELL_BIOS), "Invalid for \
> - power well status to be enabled, unless done \
> - by the BIOS, when request is to disable!\n");
> - if (GEN9_ENABLE_DC5(dev) &&
> - power_well->data == SKL_DISP_PW_2)
> - gen9_disable_dc5(dev_priv);
> - I915_WRITE(HSW_PWR_WELL_DRIVER, tmp | req_mask);
> + if (enable && (!enable_requested)) {
> + WARN(is_enabled && !I915_READ(HSW_PWR_WELL_BIOS),
> + "Invalid for power well status to be enabled, unless done by \
> + the BIOS, when request is to disable!\n");
> + if (SKL_ENABLE_DC6(dev) && power_well->data == SKL_DISP_PW_2) {
> + skl_disable_dc6(dev_priv);
> + /*
> + * DDI buffer programming unnecessary during driver
> + * load/resumeas it's already done during modeset
> + * initialization then. It's also invalid here as
> + * encoder list is still uninitialized.

Some typos in the above comment.

> + */
> + if (!dev_priv->power_domains.initializing)
> + intel_prepare_ddi(dev);
> }
> -
> - if (!is_enabled) {
> - DRM_DEBUG_KMS("Enabling %s\n", power_well->name);
> - if (wait_for((I915_READ(HSW_PWR_WELL_DRIVER) &
> - state_mask), 1))
> - DRM_ERROR("%s enable timeout\n",
> - power_well->name);
> + if (GEN9_ENABLE_DC5(dev) && power_well->data == SKL_DISP_PW_2)
> + gen9_disable_dc5(dev_priv);
> + I915_WRITE(HSW_PWR_WELL_DRIVER, tmp | req_mask);
> + }
> + if (enable && (!is_enabled)) {
> + DRM_DEBUG_KMS("Enabling %s\n", power_well->name);
> + if (wait_for((I915_READ(HSW_PWR_WELL_DRIVER) & state_mask), 1))
> + DRM_ERROR("%s enable timeout\n", power_well->name);
> check_fuse_status = true;
> - }
> - } else {
> - if (enable_requested) {
> - I915_WRITE(HSW_PWR_WELL_DRIVER, tmp & ~req_mask);
> - POSTING_READ(HSW_PWR_WELL_DRIVER);
> - DRM_DEBUG_KMS("Disabling %s\n", power_well->name);
> -
> - if (GEN9_ENABLE_DC5(dev) &&
> - power_well->data == SKL_DISP_PW_2) {
> - if (!dev_priv->csr.failed) {
> - /*
> - * TODO: wait for a completion event or
> - * similar here instead of busy
> - * waiting using wait_for function.
> - */
> - if (wait_for(
> - intel_csr_load_status_get(
> - dev_priv), 1000))
> - DRM_ERROR("Timed out waiting \
> - for CSR to be loaded!");
> - else
> - gen9_enable_dc5(dev_priv);
> - } else {
> - DRM_ERROR("Cannot enable DC5 as CSR \
> - failed to load!");
> - }
> + }
> + if ((!enable) && enable_requested) {
> + I915_WRITE(HSW_PWR_WELL_DRIVER, tmp & ~req_mask);
> + POSTING_READ(HSW_PWR_WELL_DRIVER);
> + DRM_DEBUG_KMS("Disabling %s\n", power_well->name);
> +
> + if ((GEN9_ENABLE_DC5(dev) || SKL_ENABLE_DC6(dev)) &&
> + power_well->data == SKL_DISP_PW_2) {
> + if (dev_priv->csr.failed) {
> + DRM_ERROR("CSR loading failed, not entering %s",
> + SKL_ENABLE_DC6(dev) ? "DC6" : "DC5");
> + goto exit;
> + }
> + /*
> + * TODO: wait for a completion event or similar here
> + * instead of busy waiting using wait_for function.
> + */
> + if (wait_for(intel_csr_load_status_get(dev_priv),
> + 1000)) {
> + DRM_ERROR("Timed out for CSR loading!");
> + goto exit;
> }
> + if (SKL_ENABLE_DC6(dev))
> + skl_enable_dc6(dev_priv);
> + else
> + gen9_enable_dc5(dev_priv);
> }
> }
>
> +exit:
> if (check_fuse_status) {
> if (power_well->data == SKL_DISP_PW_1) {
> if (wait_for((I915_READ(SKL_FUSE_STATUS) &

No need to change anything about this now, but there are a quite a lot
of rewrites here for things that were added earlier in the patchset and
there is really no good reason for this. In the future it would make the
review easier if you would squash/organize the patches so as to minimize
such rewrites.

With the above things fixed:
Reviewed-by: Imre Deak <imre.deak@intel.com>