From 218151e997449717cbb70f304b7b8f9918ba6af4 Mon Sep 17 00:00:00 2001 From: Daniele Ceraolo Spurio Date: Mon, 14 Oct 2019 11:36:01 -0700 Subject: drm/i915/guc: improve documentation Add a short description of what we expect from GuC and some minor improvements to existing documentation. Also remove a comment about a difference between GuC and HuC that is not true anymore. v2: add that the GuC is not mandatory (Martin) v3: add extra newline for better text organization (Martin) Signed-off-by: Daniele Ceraolo Spurio Cc: Michal Wajdeczko Cc: Matthew Brost Cc: Martin Peres Acked-by: Anna Karas Reviewed-by: Martin Peres Link: https://patchwork.freedesktop.org/patch/msgid/20191014183602.3643-2-daniele.ceraolospurio@intel.com --- drivers/gpu/drm/i915/gt/uc/intel_guc.c | 31 +++++++++++++++++++++-- drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 6 +++++ drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h | 3 --- 3 files changed, 35 insertions(+), 5 deletions(-) (limited to 'drivers/gpu/drm/i915') diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c index 249c747e9756..37f7bcbf7dac 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c @@ -9,6 +9,27 @@ #include "intel_guc_submission.h" #include "i915_drv.h" +/** + * DOC: GuC + * + * The GuC is a microcontroller inside the GT HW, introduced in gen9. The GuC is + * designed to offload some of the functionality usually performed by the host + * driver; currently the main operations it can take care of are: + * + * - Authentication of the HuC, which is required to fully enable HuC usage. + * - Low latency graphics context scheduling (a.k.a. GuC submission). + * - GT Power management. + * + * The enable_guc module parameter can be used to select which of those + * operations to enable within GuC. Note that not all the operations are + * supported on all gen9+ platforms. + * + * Enabling the GuC is not mandatory and therefore the firmware is only loaded + * if at least one of the operations is selected. However, not loading the GuC + * might result in the loss of some features that do require the GuC (currently + * just the HuC, but more are expected to land in the future). + */ + static void gen8_guc_raise_irq(struct intel_guc *guc) { struct intel_gt *gt = guc_to_gt(guc); @@ -548,9 +569,15 @@ int intel_guc_resume(struct intel_guc *guc) } /** - * DOC: GuC Address Space + * DOC: GuC Memory Management * - * The layout of GuC address space is shown below: + * GuC can't allocate any memory for its own usage, so all the allocations must + * be handled by the host driver. GuC accesses the memory via the GGTT, with the + * exception of the top and bottom parts of the 4GB address space, which are + * instead re-mapped by the GuC HW to memory location of the FW itself (WOPCM) + * or other parts of the HW. The driver must take care not to place objects that + * the GuC is going to access in these reserved ranges. The layout of the GuC + * address space is shown below: * * :: * diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index f325d3dd564f..849a44add424 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -29,6 +29,12 @@ enum { /** * DOC: GuC-based command submission * + * IMPORTANT NOTE: GuC submission is currently not supported in i915. The GuC + * firmware is moving to an updated submission interface and we plan to + * turn submission back on when that lands. The below documentation (and related + * code) matches the old submission model and will be updated as part of the + * upgrade to the new flow. + * * GuC client: * A intel_guc_client refers to a submission path through GuC. Currently, there * is only one client, which is charged with all submissions to the GuC. This diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h index f8f6c91a0df6..029214cdedd5 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw_abi.h @@ -39,9 +39,6 @@ * 3. Length info of each component can be found in header, in dwords. * 4. Modulus and exponent key are not required by driver. They may not appear * in fw. So driver will load a truncated firmware in this case. - * - * The only difference between GuC and HuC firmwares is how the version - * information is saved. */ struct uc_css_header { -- cgit v1.2.3