On Tue, 19 Sep 2017 19:42:00 +0200, Sagar Arun Kamble <sagar.a.kam...@intel.com> wrote:

This patch adds two debugfs interfaces:
1. i915_slpc_paramlist: List of all parameters that Host can configure.
   Currently listing id and description of each.
2. i915_slpc_param_ctl: This allows to change the parameters. Syntax is:
   echo "write <id> <value>" > i915_slpc_param_ctl.
   echo "read <id>" > i915_slpc_param_ctl; cat i915_slpc_param_ctl
   revert allows to set to default SLPC internal values. Syntax is:
   echo "revert <id>" > i915_slpc_param_ctl.

Added support to set/read parameters and unset the parameters which will
revert them to default SLPC internal values. Also added RPM ref. cover
around set/unset calls. Explicit SLPC reset is needed on setting/unsetting
some of the parameters.

Signed-off-by: Sagar Arun Kamble <sagar.a.kam...@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c |  19 +++++
drivers/gpu/drm/i915/intel_slpc.c | 158 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_slpc.h   |   6 ++
 3 files changed, 183 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index dbfe185..0a04f3d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2352,6 +2352,23 @@ static int i915_huc_load_status_info(struct seq_file *m, void *data)
        return 0;
 }
+static int i915_slpc_paramlist_info(struct seq_file *m, void *data)

I'm little confused that part of the debugfs functionality is done here
while other part in slpc.c

+{
+       struct drm_i915_private *dev_priv = node_to_i915(m->private);
+       int i;
+
+       if (!dev_priv->guc.slpc.active) {

intel_slpc_active() ?

+               seq_puts(m, "SLPC not active\n");
+               return 0;
+       }
+
+       seq_puts(m, "Param id\tParam description\n");
+       for (i = 0; i < SLPC_MAX_PARAM; i++)
+               seq_printf(m, "%8d\t%s\n", slpc_paramlist[i].id,
+                                          slpc_paramlist[i].description);

What if size of slpc_paramlist[] will be smaller than i ?

+       return 0;
+}
+
 static int i915_guc_load_status_info(struct seq_file *m, void *data)
 {
        struct drm_i915_private *dev_priv = node_to_i915(m->private);
@@ -4881,6 +4898,7 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
        {"i915_guc_load_err_log_dump", i915_guc_log_dump, 0, (void *)1},
        {"i915_guc_stage_pool", i915_guc_stage_pool, 0},
        {"i915_huc_load_status", i915_huc_load_status_info, 0},
+       {"i915_slpc_paramlist", i915_slpc_paramlist_info, 0},
        {"i915_frequency_info", i915_frequency_info, 0},
        {"i915_hangcheck_info", i915_hangcheck_info, 0},
        {"i915_reset_info", i915_reset_info, 0},
@@ -4944,6 +4962,7 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
        {"i915_dp_test_type", &i915_displayport_test_type_fops},
        {"i915_dp_test_active", &i915_displayport_test_active_fops},
        {"i915_guc_log_control", &i915_guc_log_control_fops},
+       {"i915_slpc_param_ctl", &i915_slpc_param_ctl_fops},
        {"i915_hpd_storm_ctl", &i915_hpd_storm_ctl_fops},
        {"i915_ipc_status", &i915_ipc_status_fops}
 };
diff --git a/drivers/gpu/drm/i915/intel_slpc.c b/drivers/gpu/drm/i915/intel_slpc.c
index d0fd402..0c094f0 100644
--- a/drivers/gpu/drm/i915/intel_slpc.c
+++ b/drivers/gpu/drm/i915/intel_slpc.c
@@ -25,6 +25,8 @@
 #include <asm/msr-index.h>
 #include "i915_drv.h"
 #include "intel_uc.h"
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
struct slpc_param slpc_paramlist[SLPC_MAX_PARAM] = {
        {SLPC_PARAM_TASK_ENABLE_GTPERF, "Enable task GTPERF"},
@@ -684,3 +686,159 @@ void intel_slpc_disable(struct intel_slpc *slpc)
        slpc->active = false;
 }
+
+static int slpc_param_ctl_show(struct seq_file *m, void *data)
+{
+       struct drm_i915_private *dev_priv = m->private;
+       struct intel_slpc *slpc = &dev_priv->guc.slpc;
+
+       if (!slpc->active) {

intel_slpc_active() ?

+               seq_puts(m, "SLPC not active\n");
+               return 0;
+       }
+
+       seq_printf(m, "%s=%u, override=%s\n",
+                       slpc_paramlist[slpc->debug_param_id].description,
+                       slpc->debug_param_value,
+                       yesno(!!slpc->debug_param_override));
+

What if slpc->debug_param_id >= SLPC_MAX_PARAM or sizeof paramlist ?

+       return 0;
+}
+
+static int slpc_param_ctl_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, slpc_param_ctl_show, inode->i_private);
+}
+
+static const char *read_token = "read", *write_token = "write",
+                 *revert_token = "revert";
+
+/*
+ * Parse SLPC parameter control strings: (Similar to Pipe CRC handling)
+ *   command: wsp* op wsp+ param id wsp+ [value] wsp*
+ *   op: "read"/"write"/"revert"
+ *   param id: slpc_param_id
+ *   value: u32 value
+ *   wsp: (#0x20 | #0x9 | #0xA)+
+ *
+ * eg.:
+ *  "read 0"         -> read SLPC_PARAM_TASK_ENABLE_GTPERF
+ * "write 7 500" -> set SLPC_PARAM_GLOBAL_MIN_GT_SLICE_FREQ_MHZ to 500MHz
+ *  "revert 7"               -> revert SLPC_PARAM_GLOBAL_MIN_GT_SLICE_FREQ_MHZ 
to
+ *                        default value.
+ */
+static int slpc_param_ctl_parse(char *buf, size_t len, char **op,
+                               u32 *id, u32 *value)
+{
+#define MAX_WORDS 3
+       int n_words;
+       char *words[MAX_WORDS];
+       ssize_t ret;
+
+       n_words = buffer_tokenize(buf, words, MAX_WORDS);

Ha! finally found the purpose of the patch 001
Please try to keep them closer.

+       if (!(n_words == 3) && !(n_words == 2)) {
+               DRM_DEBUG_DRIVER("tokenize failed, a command is %d words\n",
+                                MAX_WORDS);
+               return -EINVAL;
+       }
+
+       if (strcmp(words[0], read_token) && strcmp(words[0], write_token) &&
+           strcmp(words[0], revert_token)) {
+               DRM_DEBUG_DRIVER("unknown operation\n");

Please add operation word into message for easier debug

+               return -EINVAL;
+       }
+
+       *op = words[0];

Hmm, this will cause yet another strcmp - try to convert into OP code.

+
+       ret = kstrtou32(words[1], 0, id);
+       if (ret)
+               return ret;
+
+       if (n_words == 3) {
+               ret = kstrtou32(words[2], 0, value);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;

Shouldn't we return n_words-1 to easier catch any missing params?

+}
+
+static ssize_t slpc_param_ctl_write(struct file *file, const char __user *ubuf,
+                                    size_t len, loff_t *offp)
+{
+       struct seq_file *m = file->private_data;
+       struct drm_i915_private *dev_priv = m->private;
+       struct intel_slpc *slpc = &dev_priv->guc.slpc;
+       char *tmpbuf, *op = NULL;
+       u32 id, value;
+       int ret;
+
+       if (len == 0)
+               return 0;
+
+       if (len > 40) {
+               DRM_DEBUG_DRIVER("expected <40 chars into slpc_param_ctl\n");
+               return -E2BIG;
+       }
+
+       tmpbuf = kmalloc(len + 1, GFP_KERNEL);
+       if (!tmpbuf)
+               return -ENOMEM;
+
+       if (copy_from_user(tmpbuf, ubuf, len)) {
+               ret = -EFAULT;
+               goto out;
+       }
+       tmpbuf[len] = '\0';
+
+       ret = slpc_param_ctl_parse(tmpbuf, len, &op, &id, &value);

'ret' is not checked for errors

+
+       if (id >= SLPC_MAX_PARAM) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       if (!strcmp(op, read_token)) {
+               intel_slpc_get_param(slpc, id,
+                                    &slpc->debug_param_override,
+                                    &slpc->debug_param_value);
+               slpc->debug_param_id = id;
+       } else if (!strcmp(op, write_token) || !strcmp(op, revert_token)) {
+               if ((id >= SLPC_PARAM_TASK_ENABLE_GTPERF) &&
+                   (id <= SLPC_PARAM_TASK_DISABLE_DCC)) {
+                       DRM_DEBUG_DRIVER("Tasks are not controlled by "
+                                        "this interface\n");
+                       ret = -EINVAL;
+                       goto out;
+               }
+
+               /*
+                * After updating parameters, RESET event has to be sent to GuC
+                * SLPC for ensuring parameters take effect.
+                */
+               intel_runtime_pm_get(dev_priv);
+               if (!strcmp(op, write_token))
+                       intel_slpc_set_param(slpc, id, value);
+               else if (!strcmp(op, revert_token))
+                       intel_slpc_unset_param(slpc, id);
+               intel_slpc_enable(slpc);
+               intel_runtime_pm_put(dev_priv);
+       }
+
+out:
+       kfree(tmpbuf);
+       if (ret < 0)
+               return ret;
+
+       *offp += len;
+       return len;
+}
+
+const struct file_operations i915_slpc_param_ctl_fops = {
+       .owner = THIS_MODULE,
+       .open = slpc_param_ctl_open,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+       .write = slpc_param_ctl_write
+};
diff --git a/drivers/gpu/drm/i915/intel_slpc.h b/drivers/gpu/drm/i915/intel_slpc.h
index ae857d3..e49c513 100644
--- a/drivers/gpu/drm/i915/intel_slpc.h
+++ b/drivers/gpu/drm/i915/intel_slpc.h
@@ -32,6 +32,10 @@ struct intel_slpc {
        /* i915 cached SLPC frequency limits */
        u32 min_unslice_freq;
        u32 max_unslice_freq;
+
+       u32 debug_param_id;
+       u32 debug_param_value;
+       u32 debug_param_override;

Group above under 'debug' sub-struct

 };
static inline int intel_slpc_enabled(void)
@@ -251,6 +255,8 @@ struct slpc_param {
 #define SLPC_PARAM_TASK_DISABLED 2
 #define SLPC_PARAM_TASK_UNKNOWN  3
+extern const struct file_operations i915_slpc_param_ctl_fops;
+
 /* intel_slpc.c */
 void intel_slpc_set_param(struct intel_slpc *slpc, u32 id, u32 value);
 void intel_slpc_unset_param(struct intel_slpc *slpc, u32 id);
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