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

Sagar Arun Kamble
2017-09-28T10:19:01Z

On 9/21/2017 8:37 PM, Michal Wajdeczko wrote:
> 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
Will pull them together. It was to allow new interfaces to make use of
the functionality 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() ?
yes. will update.
>
>> +        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 ?
will add the size checks.
>
>> +    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() ?
yes. will update.
>
>> +        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 ?
will add the check.
>
>> +    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.
ok. will bring that closer. Thinking was to keep all drm/i915/slpc
patches together.
>
>> +    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
It is there. :) Did you mean "unknown operation word" ?
>
>> +        return -EINVAL;
>> +    }
>> +
>> +    *op = words[0];
>
> Hmm, this will cause yet another strcmp - try to convert into OP code.
Ok. will update.
>
>> +
>> +    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?
Yes. Will add this.
>
>> +}
>> +
>> +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
Will check now with above return fixed.
>
>> +
>> +    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
Sure.
>
>>  };
>> 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);