Re: [PATCH 5/7] drm/i915: Update kerneldoc for intel_dpll_mgr.c

Daniel Vetter
2016-10-13T13:46:49Z

On Tue, Oct 04, 2016 at 03:32:15PM +0300, Ander Conselvan de Oliveira wrote:
> The documentation for most of the non-static members and structs were
> missing. Fix that.
>
> v2: Fix typos (Durga)
>
> v3: Rebase.
> Fix make docs warnings.
> Document more.
>
> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>

As mentioned in an earlier patch, I think we should also move
intel_atomic_get_shared_dpll_state from intel_atomic.c into
intel_dpll_mgr.c. Grouping functions by the data structures they touch
makes imo much more sense, than grouping them by topic. That way all the
dpll stuff is in one place.

> ---
> Documentation/gpu/i915.rst | 12 +++
> drivers/gpu/drm/i915/intel_dpll_mgr.c | 90 ++++++++++++++++++--
> drivers/gpu/drm/i915/intel_dpll_mgr.h | 155 ++++++++++++++++++++++++++++++----
> 3 files changed, 237 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
> index 87aaffc..c19e437 100644
> --- a/Documentation/gpu/i915.rst
> +++ b/Documentation/gpu/i915.rst
> @@ -204,6 +204,18 @@ Video BIOS Table (VBT)
> .. kernel-doc:: drivers/gpu/drm/i915/intel_vbt_defs.h
> :internal:
>
> +Display PLLs
> +------------
> +
> +.. kernel-doc:: drivers/gpu/drm/i915/intel_dpll_mgr.c
> + :doc: Display PLLs
> +
> +.. kernel-doc:: drivers/gpu/drm/i915/intel_dpll_mgr.c
> + :internal:
> +
> +.. kernel-doc:: drivers/gpu/drm/i915/intel_dpll_mgr.h
> + :internal:
> +
> Memory Management and Command Submission
> ========================================
>
> diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> index 9446446..8c4efa9 100644
> --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> @@ -23,6 +23,25 @@
>
> #include "intel_drv.h"
>
> +/**
> + * DOC: Display PLLs
> + *
> + * Display PLLs used for driving outputs vary by platform. While some have
> + * per-pipe or per-encoder dedicated PLLs, others allow the use of any PLL
> + * from a pool. In the latter scenario, it is possible that multiple pipes
> + * share a PLL if their configurations match.
> + *
> + * This file provides an abstraction over display PLLs. The function
> + * intel_shared_dpll_init() initializes the PLLs for the given platform. The
> + * users of a PLL are tracked and that tracking is integrated with the atomic
> + * modest interface. During an atomic operation, a PLL can be requested for a
> + * given crtc and encoder configuration by calling intel_get_shared_dpll() and

s/crtc/CRTC/ for consistency (abbreviations are all upercase), pls do that
on the entire doc.

> + * a previously used PLL can be released with intel_release_shared_dpll().
> + * Changes to the users are first staged in the atomic state, and then made
> + * effective by calling intel_shared_dpll_swap_state() during the atomic
> + * commit phase.
> + */
> +
> struct intel_shared_dpll *
> skl_find_link_pll(struct drm_i915_private *dev_priv, int clock)
> {
> @@ -61,6 +80,14 @@ skl_find_link_pll(struct drm_i915_private *dev_priv, int clock)
> return pll;
> }
>
> +/**
> + * intel_get_shared_dpll_by_id - get a DPLL given its id
> + * @dev_priv: i915 device instance
> + * @id: pll id
> + *
> + * Returns:
> + * A pointer to the DPLL with @id
> + */
> struct intel_shared_dpll *
> intel_get_shared_dpll_by_id(struct drm_i915_private *dev_priv,
> enum intel_dpll_id id)
> @@ -68,6 +95,14 @@ intel_get_shared_dpll_by_id(struct drm_i915_private *dev_priv,
> return &dev_priv->shared_dplls[id];
> }
>
> +/**
> + * intel_get_shared_dpll_id - get the id of a DPLL
> + * @dev_priv: i915 device instance
> + * @pll: the DPLL
> + *
> + * Returns:
> + * The id of @pll
> + */
> enum intel_dpll_id
> intel_get_shared_dpll_id(struct drm_i915_private *dev_priv,
> struct intel_shared_dpll *pll)
> @@ -96,6 +131,13 @@ void assert_shared_dpll(struct drm_i915_private *dev_priv,
> pll->name, onoff(state), onoff(cur_state));
> }
>
> +/**
> + * intel_prepare_shared_dpll - call a dpll's prepare hook
> + * @crtc: crtc which has a shared dpll
> + *
> + * This calls the PLL's prepare hook if it has one and if the PLL is not
> + * already enabled. The prepare hook is platform specific.
> + */
> void intel_prepare_shared_dpll(struct intel_crtc *crtc)
> {
> struct drm_device *dev = crtc->base.dev;
> @@ -118,12 +160,10 @@ void intel_prepare_shared_dpll(struct intel_crtc *crtc)
> }
>
> /**
> - * intel_enable_shared_dpll - enable PCH PLL
> - * @dev_priv: i915 private structure
> - * @pipe: pipe PLL to enable
> + * intel_enable_shared_dpll - enable a crtc's shared DPLL
> + * @crtc: crtc which has a shared DPLL
> *
> - * The PCH PLL needs to be enabled before the PCH transcoder, since it
> - * drives the transcoder clock.
> + * Enable the shared DPLL used by @crtc.
> */
> void intel_enable_shared_dpll(struct intel_crtc *crtc)
> {
> @@ -164,6 +204,12 @@ out:
> mutex_unlock(&dev_priv->dpll_lock);
> }
>
> +/**
> + * intel_disable_shared_dpll - disable a crtc's shared DPLL
> + * @crtc: crtc which has a shared DPLL
> + *
> + * Disable the shared DPLL used by @crtc.
> + */
> void intel_disable_shared_dpll(struct intel_crtc *crtc)
> {
> struct drm_device *dev = crtc->base.dev;
> @@ -266,6 +312,16 @@ intel_reference_shared_dpll(struct intel_shared_dpll *pll,
> shared_dpll[pll->id].crtc_mask |= 1 << crtc->pipe;
> }
>
> +/**
> + * intel_shared_dpll_swap_state - make atomic DPLL configuration effective
> + * @state: atomic state
> + *
> + * This is the dpll version of drm_atomic_helper_swap_state() since the
> + * helper does not handle driver-specific global state.
> + *
> + * Note that this doesn't actually swap states, the dpll configutation in
> + * @state is left unchanged.

Hm, what do you mean with that? I guess you mean that it only puts the
state from drm_atomic_state into dev_priv, and not the other way round.
Tbh that's a bit unexpected (yes atm we don't have a reason for that), so
instead of documenting this oddity I'd just fix it. And then maybe mention
that "For consistency with atomic helpers this also puts the current state
into @state, i.e. it does a complete swap, even though right now that's
not needed."

> + */
> void intel_shared_dpll_swap_state(struct drm_atomic_state *state)
> {
> struct drm_i915_private *dev_priv = to_i915(state->dev);
> @@ -1822,6 +1878,12 @@ static const struct intel_dpll_mgr bxt_pll_mgr = {
> .get_dpll = bxt_get_dpll,
> };
>
> +/**
> + * intel_shared_dpll_init - Initialize shared DPLLs
> + * @dev: drm device
> + *
> + * Initialize shared DPLLs for @dev.
> + */
> void intel_shared_dpll_init(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = to_i915(dev);
> @@ -1865,6 +1927,21 @@ void intel_shared_dpll_init(struct drm_device *dev)
> intel_ddi_pll_init(dev);
> }
>
> +/**
> + * intel_get_shared_dpll - get a shared DPLL for crtc and encoder combination
> + * @crtc: crtc
> + * @crtc_state: atomic state for @crtc
> + * @encoder: encoder
> + *
> + * Find an appropriate DPLL for the given crtc and encoder combination. A
> + * reference from the @crtc to the returned pll is registered in the atomic
> + * state. That configuration is made effective by calling
> + * intel_shared_dpll_swap_state(). The reference should be released by calling
> + * intel_release_shared_dpll().
> + *
> + * Returns:
> + * A shared DPLL to be used by @crtc and @encoder with the given @crtc_state.
> + */
> struct intel_shared_dpll *
> intel_get_shared_dpll(struct intel_crtc *crtc,
> struct intel_crtc_state *crtc_state,
> @@ -1885,6 +1962,9 @@ intel_get_shared_dpll(struct intel_crtc *crtc,
> * @crtc: crtc
> * @state: atomic state
> *
> + * This function releases the reference from @crtc to @dpll from the
> + * atomic @state. The new configuration is made effective by calling
> + * intel_shared_dpll_swap_state().
> */
> void intel_release_shared_dpll(struct intel_shared_dpll *dpll,
> struct intel_crtc *crtc,
> diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.h b/drivers/gpu/drm/i915/intel_dpll_mgr.h
> index 9a7db65..40f1a6f 100644
> --- a/drivers/gpu/drm/i915/intel_dpll_mgr.h
> +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.h
> @@ -40,32 +40,72 @@ struct intel_encoder;
> struct intel_shared_dpll;
> struct intel_dpll_mgr;
>
> +/**
> + * enum intel_dpll_id - possible DPLL ids
> + *
> + * Enumeration of possible IDs for a DPLL. Real shared dpll ids must be >= 0.
> + */
> enum intel_dpll_id {
> - DPLL_ID_PRIVATE = -1, /* non-shared dpll in use */
> - /* real shared dpll ids must be >= 0 */
> + /**
> + * @DPLL_ID_PRIVATE: non-shared dpll in use
> + */
> + DPLL_ID_PRIVATE = -1,
> +
> + /**
> + * @DPLL_ID_PCH_PLL_A: DPLL A in ILK, SNB and IVB
> + */
> DPLL_ID_PCH_PLL_A = 0,
> + /**
> + * @DPLL_ID_PCH_PLL_B: DPLL B in ILK, SNB and IVB
> + */
> DPLL_ID_PCH_PLL_B = 1,
> - /* hsw/bdw */
> +
> +
> + /**
> + * @DPLL_ID_WRPLL1: HSW and BDW WRPLL1
> + */
> DPLL_ID_WRPLL1 = 0,
> + /**
> + * @DPLL_ID_WRPLL2: HSW and BDW WRPLL2
> + */
> DPLL_ID_WRPLL2 = 1,
> + /**
> + * @DPLL_ID_SPLL: HSW and BDW SPLL
> + */
> DPLL_ID_SPLL = 2,
> + /**
> + * @DPLL_ID_LCPLL_810: HSW and BDW 0.81 GHz LCPLL
> + */
> DPLL_ID_LCPLL_810 = 3,
> + /**
> + * @DPLL_ID_LCPLL_1350: HSW and BDW 1.35 GHz LCPLL
> + */
> DPLL_ID_LCPLL_1350 = 4,
> + /**
> + * @DPLL_ID_LCPLL_2700: HSW and BDW 2.7 GHz LCPLL
> + */
> DPLL_ID_LCPLL_2700 = 5,
>
> - /* skl */
> +
> + /**
> + * @DPLL_ID_SKL_DPLL0: SKL and later DPLL0
> + */
> DPLL_ID_SKL_DPLL0 = 0,
> + /**
> + * @DPLL_ID_SKL_DPLL1: SKL and later DPLL1
> + */
> DPLL_ID_SKL_DPLL1 = 1,
> + /**
> + * @DPLL_ID_SKL_DPLL2: SKL and later DPLL2
> + */
> DPLL_ID_SKL_DPLL2 = 2,
> + /**
> + * @DPLL_ID_SKL_DPLL3: SKL and later DPLL3
> + */
> DPLL_ID_SKL_DPLL3 = 3,
> };
> #define I915_NUM_PLLS 6
>
> -/** Inform the state checker that the DPLL is kept enabled even if not
> - * in use by any crtc.
> - */
> -#define INTEL_DPLL_ALWAYS_ON (1 << 0)
> -
> struct intel_dpll_hw_state {
> /* i9xx, pch plls */
> uint32_t dpll;
> @@ -93,39 +133,124 @@ struct intel_dpll_hw_state {
> pcsdw12;
> };
>
> +/**
> + * struct intel_shared_dpll_state - hold the DPLL atomic state
> + *
> + * This structure holds an atomic state for the DPLL, that can represent
> + * either its current state or a desired furture state which would be
> + * applied by an atomic mode set.

I think it'd be good to reference where we store pointers to that, i.e.
where in intel_atomic_state and intel_shared_dpll it sits. Best if you do that
using the struct &intel_atomic_state reference style (so that it becomes a
hyperlink once that's documented).

Also links to the main functions used to manage this would be good I
think, i.e. release and get.

> + */
> struct intel_shared_dpll_state {
> - unsigned crtc_mask; /* mask of CRTCs sharing this PLL */
> + /**
> + * @crtc_mask: mask of crtc using this DPLL, active or not

s/crtc/CRTCs/

> + */
> + unsigned crtc_mask;
> +
> + /**
> + * @hw_state: hardware configuration for the DPLL.

"... stored in struct &intel_dpll_hw_state." - I love my hyperlinks ;-)

> + */
> struct intel_dpll_hw_state hw_state;
> };
>
> +/**
> + * struct intel_shared_dpll_funcs - platform specific hooks for managing DPLLs
> + */
> struct intel_shared_dpll_funcs {
> - /* The mode_set hook is optional and should be used together with the
> - * intel_prepare_shared_dpll function. */
> + /**
> + * @prepare:
> + *
> + * Optional hook to perform operations prior to enabling the PLL.
> + * Called from intel_prepare_shared_dpll() function.

Missing the language about "if the pll is not already enabled."

> + */
> void (*prepare)(struct drm_i915_private *dev_priv,
> struct intel_shared_dpll *pll);
> +
> + /**
> + * @enable:
> + *
> + * Hook for enabling the pll, called from intel_enable_shared_dpll()
> + * if the pll is not already enabled.
> + */
> void (*enable)(struct drm_i915_private *dev_priv,
> struct intel_shared_dpll *pll);
> +
> + /**
> + * @disable:
> + *
> + * Hook for disabling the pll, called from intel_disable_shared_dpll()
> + * only when it is safe to disable the pll, i.e., there are no more
> + * tracked users for it.
> + */
> void (*disable)(struct drm_i915_private *dev_priv,
> struct intel_shared_dpll *pll);
> +
> + /**
> + * @get_hw_state:
> + *
> + * Hook for reading the values currently programmed to the DPLL
> + * registers. This is used for initial hw state readout and state
> + * verification after a mode set.
> + */
> bool (*get_hw_state)(struct drm_i915_private *dev_priv,
> struct intel_shared_dpll *pll,
> struct intel_dpll_hw_state *hw_state);
> };
>
> +/**
> + * struct intel_shared_dpll - display PLL with tracked state and users
> + */
> struct intel_shared_dpll {
> + /**
> + * @state:
> + *
> + * Store the state for the pll, including the its hw state
> + * and crtcs using it.
> + */
> struct intel_shared_dpll_state state;
>
> - unsigned active_mask; /* mask of active CRTCs (i.e. DPMS on) */
> - bool on; /* is the PLL actually active? Disabled during modeset */
> + /**
> + * @active_mask: mask of active CRTCs (i.e. DPMS on) using this DPLL
> + */
> + unsigned active_mask;
> +
> + /**
> + * @on: is the PLL actually active? Disabled during modeset
> + */
> + bool on;
> +
> + /**
> + * @name: DPLL name; used for logging
> + */
> const char *name;
> - /* should match the index in the dev_priv->shared_dplls array */
> +
> + /**
> + * @id: unique indentifier for this DPLL; should match the index in the
> + * dev_priv->shared_dplls array
> + */
> enum intel_dpll_id id;
>
> + /**
> + * @funcs: platform specific hooks
> + */
> struct intel_shared_dpll_funcs funcs;
>
> + /**
> + * @flags:
> + *
> + * accepted flags: INTEL_DPLL_ALWAYS_ON

Hm, I've started to just document flags in-line as an enumeration, to keep
things tightly grouped. And then also place the #define right in front of
the kernel-doc for @flags. See e.g. @flags in drm_property.h for a really
long example of that (but there the flags are in an uabi header, so a bit
special).

With the nitpicks addressed somehow:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> + */
> uint32_t flags;
> };
>
> +/**
> + * INTEL_DPLL_ALWAYS_ON
> + *
> + * Inform the state checker that the DPLL is kept enabled even if not
> + * in use by any crtc.
> + */
> +#define INTEL_DPLL_ALWAYS_ON (1 << 0)
> +
> +
> #define SKL_DPLL0 0
> #define SKL_DPLL1 1
> #define SKL_DPLL2 2
> --
> 2.5.5
>
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--
Daniel Vetter
Software Engineer, Intel Corporation