Re: [PATCH 24/31] drm/i915/slpc: Add debugfs support to read/write/revert the parameters

Michal Wajdeczko
2017-09-21T15:08:57Z

On Tue, 19 Sep 2017 19:42:00 +0200, Sagar Arun Kamble
<sagar.a.kamble@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.kamble@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);