[Intel-gfx] [PATCH v3 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)

v3: Optimised lmem bar size code and modified code to resize
bar maximum upto lmem_size instead of maximum supported size.(Nirmoy)

Cc: Matthew Auld <matthew.auld at intel.com>
Cc: Nirmoy Das <nirmoy.das at intel.com>
Signed-off-by: Priyanka Dandamudi <priyanka.dandamudi at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_region_lmem.c | 51 +++++++++++----------
 drivers/gpu/drm/i915/i915_params.c          |  2 +
 drivers/gpu/drm/i915/i915_params.h          |  1 +
 3 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index 3e9ed395f408..2ed80c3f6064 100644
--- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
@@ -14,6 +14,7 @@
 #include "gt/intel_gt.h"
 #include "gt/intel_gt_mcr.h"
 #include "gt/intel_gt_regs.h"
+#include "../../../pci/pci.h"
 
 static void _release_bars(struct pci_dev *pdev)
 {
@@ -44,38 +45,38 @@ _resize_bar(struct drm_i915_private *i915, int resno, resource_size_t size)
 	drm_info(&i915->drm, "BAR%d resized to %dM\n", resno, 1 << bar_size);
 }
 
-/* BAR size starts from 1MB - 2^20 */
-#define BAR_SIZE_SHIFT 20
-static resource_size_t
-_lmem_rebar_size(struct drm_i915_private *i915, int resno)
-{
-	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
-	u32 rebar = pci_rebar_get_possible_sizes(pdev, resno);
-	resource_size_t size;
-
-	if (!rebar)
-		return 0;
-
-	size = 1ULL << (__fls(rebar) + BAR_SIZE_SHIFT);
-
-	if (size <= pci_resource_len(pdev, resno))
-		return 0;
-
-	return size;
-}
-
 #define LMEM_BAR_NUM 2
-static void i915_resize_lmem_bar(struct drm_i915_private *i915)
+static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t lmem_size)
 {
 	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	struct pci_bus *root = pdev->bus;
 	struct resource *root_res;
-	resource_size_t rebar_size = _lmem_rebar_size(i915, LMEM_BAR_NUM);
+	resource_size_t rebar_size;
+	resource_size_t current_size;
 	u32 pci_cmd;
 	int i;
 
-	if (!rebar_size)
-		return;
+	current_size = roundup_pow_of_two(pci_resource_len(pdev, LMEM_BAR_NUM));
+
+	if (i915->params.lmem_bar_size) {
+		resource_size_t min_bar_size = pci_rebar_size_to_bytes
+			(__ffs(pci_rebar_get_possible_sizes(pdev, LMEM_BAR_NUM)));
+
+		rebar_size = pci_rebar_size_to_bytes(__fls(i915->params.lmem_bar_size));
+
+		if (rebar_size == current_size)
+			return;
+
+		if (rebar_size >= roundup_pow_of_two(lmem_size) || rebar_size < min_bar_size)
+			rebar_size = lmem_size;
+	} else {
+		rebar_size = current_size;
+
+		if (rebar_size != roundup_pow_of_two(lmem_size))
+			rebar_size = lmem_size;
+		else
+			return;
+	}
 
 	/* Find out if root bus contains 64bit memory addressing */
 	while (root->parent)
@@ -217,7 +218,7 @@ static struct intel_memory_region *setup_lmem(struct intel_gt *gt)
 		lmem_size = intel_uncore_read64(&i915->uncore, GEN12_GSMBASE);
 	}
 
-	i915_resize_lmem_bar(i915);
+	i915_resize_lmem_bar(i915, lmem_size);
 
 	if (i915->params.lmem_size > 0) {
 		lmem_size = min_t(resource_size_t, lmem_size,
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) \
-- 
2.27.0