drm/i915/dsb: Documentation for DSB. (5dd85e72) · Commits · 戴 / test

Documentation/gpu/i915.rst

+9 −0

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		@@ -246,6 +246,15 @@ Display PLLs
		.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpll_mgr.h
		:internal:

		Display State Buffer
		--------------------

		.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c
		:doc: DSB

		.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dsb.c
		:internal:

		Memory Management and Command Submission
		========================================

drivers/gpu/drm/i915/display/intel_dsb.c

+68 −0

Original line number	Diff line number	Diff line
		@@ -9,6 +9,23 @@

		#define DSB_BUF_SIZE (2 * PAGE_SIZE)

		/**
		* DOC: DSB
		*
		* A DSB (Display State Buffer) is a queue of MMIO instructions in the memory
		* which can be offloaded to DSB HW in Display Controller. DSB HW is a DMA
		* engine that can be programmed to download the DSB from memory.
		* It allows driver to batch submit display HW programming. This helps to
		* reduce loading time and CPU activity, thereby making the context switch
		* faster. DSB Support added from Gen12 Intel graphics based platform.
		*
		* DSB's can access only the pipe, plane, and transcoder Data Island Packet
		* registers.
		*
		* DSB HW can support only register writes (both indexed and direct MMIO
		* writes). There are no registers reads possible with DSB HW engine.
		*/

		/* DSB opcodes. */
		#define DSB_OPCODE_SHIFT 24
		#define DSB_OPCODE_MMIO_WRITE 0x1
		@@ -66,6 +83,17 @@ static inline bool intel_dsb_disable_engine(struct intel_dsb *dsb)
		return true;
		}

		/**
		* intel_dsb_get() - Allocate DSB context and return a DSB instance.
		* @crtc: intel_crtc structure to get pipe info.
		*
		* This function provides handle of a DSB instance, for the further DSB
		* operations.
		*
		* Returns: address of Intel_dsb instance requested for.
		* Failure: Returns the same DSB instance, but without a command buffer.
		*/

		struct intel_dsb *
		intel_dsb_get(struct intel_crtc *crtc)
		{
		@@ -116,6 +144,14 @@ err:
		return dsb;
		}

		/**
		* intel_dsb_put() - To destroy DSB context.
		* @dsb: intel_dsb structure.
		*
		* This function destroys the DSB context allocated by a dsb_get(), by
		* unpinning and releasing the VMA object associated with it.
		*/

		void intel_dsb_put(struct intel_dsb *dsb)
		{
		struct intel_crtc crtc = container_of(dsb, typeof(crtc), dsb);
		@@ -138,6 +174,19 @@ void intel_dsb_put(struct intel_dsb *dsb)
		}
		}

		/**
		* intel_dsb_indexed_reg_write() -Write to the DSB context for auto
		* increment register.
		* @dsb: intel_dsb structure.
		* @reg: register address.
		* @val: value.
		*
		* This function is used for writing register-value pair in command
		* buffer of DSB for auto-increment register. During command buffer overflow,
		* a warning is thrown and rest all erroneous condition register programming
		* is done through mmio write.
		*/

		void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
		u32 val)
		{
		@@ -202,6 +251,18 @@ void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
		buf[dsb->free_pos] = 0;
		}

		/**
		* intel_dsb_reg_write() -Write to the DSB context for normal
		* register.
		* @dsb: intel_dsb structure.
		* @reg: register address.
		* @val: value.
		*
		* This function is used for writing register-value pair in command
		* buffer of DSB. During command buffer overflow, a warning is thrown
		* and rest all erroneous condition register programming is done
		* through mmio write.
		*/
		void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val)
		{
		struct intel_crtc crtc = container_of(dsb, typeof(crtc), dsb);
		@@ -225,6 +286,13 @@ void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val)
		i915_mmio_reg_offset(reg);
		}

		/**
		* intel_dsb_commit() - Trigger workload execution of DSB.
		* @dsb: intel_dsb structure.
		*
		* This function is used to do actual write to hardware using DSB.
		* On errors, fall back to MMIO. Also this function help to reset the context.
		*/
		void intel_dsb_commit(struct intel_dsb *dsb)
		{
		struct intel_crtc crtc = container_of(dsb, typeof(crtc), dsb);

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