[Intel-gfx] [PATCH 2/2] drm/i915: Add lmem_bar_size modparam

[priyanka.dandamudi at intel.com]

From: Priyanka Dandamudi <priyanka.dandamudi at intel.com>

For testing purposes, support forcing the lmem_bar_size through a new
modparam. In CI we only have a limited number of configurations for DG2,
but we still need to be reasonably sure we get a usable device (also
verifying we report the correct values for things like
probed_cpu_visible_size etc) with all the potential lmem_bar sizes that
we might expect see in the wild.

v2: Update commit message and a minor modification.(Matt)

Cc: Matthew Auld <matthew.auld at intel.com>
Signed-off-by: Priyanka Dandamudi <priyanka.dandamudi at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_region_lmem.c |  4 +++
 drivers/gpu/drm/i915/i915_driver.c          | 28 ++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_params.c          |  2 ++
 drivers/gpu/drm/i915/i915_params.h          |  1 +
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index e9c12e0d6f59..4614c30f878f 100644
--- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
@@ -111,6 +111,10 @@ static struct intel_memory_region *setup_lmem(struct intel_gt *gt)
 		flat_ccs_base = intel_gt_read_register(gt, XEHPSDV_FLAT_CCS_BASE_ADDR);
 		flat_ccs_base = (flat_ccs_base >> XEHPSDV_CCS_BASE_SHIFT) * SZ_64K;
 
+		/* XXX: Remove this once we have small-bar uapi bits */
+		if (i915->params.lmem_bar_size > 0)
+			lmem_size = pci_resource_len(pdev, 2);
+
 		/* FIXME: Remove this when we have small-bar enabled */
 		if (pci_resource_len(pdev, 2) < lmem_size) {
 			drm_err(&i915->drm, "System requires small-BAR support, which is currently unsupported on this kernel\n");
diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index 4bdb471cb2e2..b2763b032012 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -362,8 +362,34 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915)
 	u32 pci_cmd;
 	int i;
 
-	if (!rebar_size)
+	if (i915->params.lmem_bar_size > 0) {
+		u32 lmem_bar_size;
+		u32 set_bit;
+		u32 rebar;
+		u32 msb;
+		int k;
+
+		lmem_bar_size = i915->params.lmem_bar_size;
+		rebar = pci_rebar_get_possible_sizes(pdev, LMEM_BAR_NUM);
+		msb = __fls(rebar);
+
+		for (k = msb; k >= 0; k--) {
+			set_bit = (1 << k);
+
+			if (set_bit & rebar) {
+				if (set_bit == lmem_bar_size) {
+					rebar_size = 1ULL << (__fls(lmem_bar_size) +
+							BAR_SIZE_SHIFT);
+
+					if (rebar_size == pci_resource_len(pdev, LMEM_BAR_NUM))
+						return;
+					break;
+				}
+			}
+		}
+	} else if (!rebar_size) {
 		return;
+	}
 
 	/* Find out if root bus contains 64bit memory addressing */
 	while (root->parent)
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 701fbc98afa0..6fc475a5db61 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -204,6 +204,8 @@ i915_param_named_unsafe(request_timeout_ms, uint, 0600,
 
 i915_param_named_unsafe(lmem_size, uint, 0400,
 			"Set the lmem size(in MiB) for each region. (default: 0, all memory)");
+i915_param_named_unsafe(lmem_bar_size, uint, 0400,
+			"Set the lmem bar size(in MiB).");
 
 static __always_inline void _print_param(struct drm_printer *p,
 					 const char *name,
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index b5e7ea45d191..2733cb6cfe09 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -74,6 +74,7 @@ struct drm_printer;
 	param(char *, force_probe, CONFIG_DRM_I915_FORCE_PROBE, 0400) \
 	param(unsigned int, request_timeout_ms, CONFIG_DRM_I915_REQUEST_TIMEOUT, CONFIG_DRM_I915_REQUEST_TIMEOUT ? 0600 : 0) \
 	param(unsigned int, lmem_size, 0, 0400) \
+	param(unsigned int, lmem_bar_size, 0, 0400) \
 	/* leave bools at the end to not create holes */ \
 	param(bool, enable_hangcheck, true, 0600) \
 	param(bool, load_detect_test, false, 0600) \
-- 
2.25.1