[PATCH v3 5/5] i915: map gvt pr_debug categories to bits in parameters/debug_gvt

From: Jim Cromie
Date: Wed Jul 14 2021 - 13:52:02 EST


The gvt component of this driver has ~120 pr_debugs, in 9 "classes".
Following the interface model of drm.debug, add a parameter to map
bits to these classes.

If CONFIG_DRM_USE_DYNAMIC_DEBUG=y (and CONFIG_DYNAMIC_DEBUG_CORE), add
-DDYNAMIC_DEBUG_MODULE into Makefile. TBD: maybe add a separate
CONFIG_I915_USE_DYNAMIC_DEBUG to more fully optionalize this.

In i915_params.c, add callback to map bits to queries.

TBD: the callback code should probably be moved to lib/dynamic_debug,
and given a declarative interface, with implied bit-numbering,
something like:

MOD_PARM_BITMAP_DESC(__gvt_debug,
"gvt: cmd: ", "command processing"
"gvt: core: ", "core help",
"gvt: dpy: ", "display help",
"gvt: el: ", "help",
"gvt: irq: ", "help",
"gvt: mm: ", "help",
"gvt: mmio: ", "help",
"gvt: render: ", "help",
"gvt: sched: " "help");

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
drivers/gpu/drm/i915/gvt/Makefile | 4 ++
drivers/gpu/drm/i915/i915_params.c | 76 ++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/Makefile b/drivers/gpu/drm/i915/gvt/Makefile
index ea8324abc784..846ba73b8de6 100644
--- a/drivers/gpu/drm/i915/gvt/Makefile
+++ b/drivers/gpu/drm/i915/gvt/Makefile
@@ -7,3 +7,7 @@ GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \

ccflags-y += -I $(srctree)/$(src) -I $(srctree)/$(src)/$(GVT_DIR)/
i915-y += $(addprefix $(GVT_DIR)/, $(GVT_SOURCE))
+
+#ifdef CONFIG_DRM_USE_DYNAMIC_DEBUG
+ccflags-y += -DDYNAMIC_DEBUG_MODULE
+#endif
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index e07f4cfea63a..e0d13aff5274 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -265,3 +265,79 @@ void i915_params_free(struct i915_params *params)
I915_PARAMS_FOR_EACH(FREE);
#undef FREE
}
+
+/* POC for callback -> dynamic_debug_exec_queries */
+unsigned long __gvt_debug;
+EXPORT_SYMBOL(__gvt_debug);
+
+static char *format_prefix_classes[] = {
+ "gvt: cmd: ",
+ "gvt: core: ",
+ "gvt: dpy: ",
+ "gvt: el: ",
+ "gvt: irq: ",
+ "gvt: mm: ",
+ "gvt: mmio: ",
+ "gvt: render: ",
+ "gvt: sched: "
+};
+#define NUM_CLASSES ARRAY_SIZE(format_prefix_classes)
+#define OUR_QUERY_SIZE 128 /* we need about 20 */
+
+#include <linux/module.h>
+
+static int param_set_dyndbg(const char *instr, const struct kernel_param *kp)
+{
+ unsigned int val;
+ unsigned long changes, result;
+ int rc, chgct = 0, totct = 0, bitpos;
+ char query[OUR_QUERY_SIZE];
+
+ rc = kstrtouint(instr, 0, &val);
+ if (rc) {
+ pr_err("set_dyndbg: failed\n");
+ return -EINVAL;
+ }
+ result = val;
+ pr_info("set_dyndbg: result:0x%lx from %s\n", result, instr);
+
+ changes = result ^ __gvt_debug;
+
+ for_each_set_bit(bitpos, &changes, NUM_CLASSES) {
+
+ sprintf(query, "format '^%s' %cp", format_prefix_classes[bitpos],
+ test_bit(bitpos, &result) ? '+' : '-');
+
+ chgct = dynamic_debug_exec_queries(query, "i915");
+
+ pr_info("%d changes on: %s\n", chgct, query);
+ totct += chgct;
+ }
+ pr_info("total changes: %d\n", totct);
+ __gvt_debug = result;
+ return 0;
+}
+static int param_get_dyndbg(char *buffer, const struct kernel_param *kp)
+{
+ return scnprintf(buffer, PAGE_SIZE, "%u\n",
+ *((unsigned int *)kp->arg));
+}
+static const struct kernel_param_ops param_ops_dyndbg = {
+ .set = param_set_dyndbg,
+ .get = param_get_dyndbg,
+};
+
+#define info_ln(hexi, prefix) "\n\t0x" __stringify(hexi) "\t" prefix
+
+MODULE_PARM_DESC(debug_gvt, " gvt debug categories:"
+ info_ln(1, "gvt: cmd:")
+ info_ln(2, "gvt: core:")
+ info_ln(4, "gvt: dpy:")
+ info_ln(8, "gvt: el:")
+ info_ln(10, "gvt: irq:")
+ info_ln(20, "gvt: mm:")
+ info_ln(40, "gvt: mmio:")
+ info_ln(80, "gvt: render:")
+ info_ln(100, "gvt: sched:"));
+
+module_param_cb(debug_gvt, &param_ops_dyndbg, &__gvt_debug, 0644);
--
2.31.1