On Thu, 21 Sep 2023, "Sharma, Swati2" <swati2.sharma@xxxxxxxxx> wrote:
> On 21-Sep-23 1:30 PM, Jani Nikula wrote:
>> On Wed, 13 Sep 2023, Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx> wrote:
>>> From: Swati Sharma <swati2.sharma@xxxxxxxxx>
>>>
>>> DSC_Sink_BPP_Precision entry is added to i915_dsc_fec_support_show
>>> to depict sink's precision.
>>> Also, new debugfs entry is created to enforce fractional bpp.
>>> If Force_DSC_Fractional_BPP_en is set then while iterating over
>>> output bpp with fractional step size we will continue if output_bpp is
>>> computed as integer. With this approach, we will be able to validate
>>> DSC with fractional bpp.
>>>
>>> v2:
>>> Add drm_modeset_unlock to new line(Suraj)
>>>
>>> Signed-off-by: Swati Sharma <swati2.sharma@xxxxxxxxx>
>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
>>> Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@xxxxxxxxx>
>>> Reviewed-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
>>> ---
>>> .../drm/i915/display/intel_display_debugfs.c | 83 +++++++++++++++++++
>>> .../drm/i915/display/intel_display_types.h | 1 +
>>> 2 files changed, 84 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>>> index f05b52381a83..776ab96def1f 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>>> @@ -1244,6 +1244,8 @@ static int i915_dsc_fec_support_show(struct seq_file *m, void *data)
>>> DP_DSC_YCbCr420_Native)),
>>> str_yes_no(drm_dp_dsc_sink_supports_format(intel_dp->dsc_dpcd,
>>> DP_DSC_YCbCr444)));
>>> + seq_printf(m, "DSC_Sink_BPP_Precision: %d\n",
>>> + drm_dp_dsc_sink_bpp_incr(intel_dp->dsc_dpcd));
>>> seq_printf(m, "Force_DSC_Enable: %s\n",
>>> str_yes_no(intel_dp->force_dsc_en));
>>> if (!intel_dp_is_edp(intel_dp))
>>> @@ -1436,6 +1438,84 @@ static const struct file_operations i915_dsc_output_format_fops = {
>>> .write = i915_dsc_output_format_write
>>> };
>>>
>>> +static int i915_dsc_fractional_bpp_show(struct seq_file *m, void *data)
>>> +{
>>> + struct drm_connector *connector = m->private;
>>> + struct drm_device *dev = connector->dev;
>>> + struct drm_crtc *crtc;
>>> + struct intel_dp *intel_dp;
>>> + struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
>>> + int ret;
>>> +
>>> + if (!encoder)
>>> + return -ENODEV;
>>> +
>>> + ret = drm_modeset_lock_single_interruptible(&dev->mode_config.connection_mutex);
>>> + if (ret)
>>> + return ret;
>>> +
>>> + crtc = connector->state->crtc;
>>> + if (connector->status != connector_status_connected || !crtc) {
>>> + ret = -ENODEV;
>>> + goto out;
>>> + }
>>> +
>>> + intel_dp = intel_attached_dp(to_intel_connector(connector));
>>> + seq_printf(m, "Force_DSC_Fractional_BPP_Enable: %s\n",
>>> + str_yes_no(intel_dp->force_dsc_fractional_bpp_en));
>>
>> Why "Force_DSC_Fractional_BPP_Enable" in the output?
>>
>> Usually debugfs files, like sysfs files, for stuff like this should be
>> attributes, one thing per file. Why print a long name for it, if the
>> name of the debugfs file is the name of the attribute?
>>
>> And even if you print it for humans, why the underscores?
>
> Hi Jani,
> Followed same strategy as we are doing for other dsc scenarios like
> force_dsc.
> Even naming convention followed same as other dsc stuff like
> Force_DSC_Enable, etc.
> All DSC related enteries have underscores in its naming convention.
There's value in that, though maybe my comment highlights I'm not fond
of the existing stuff. ;)
> May be i can consolidate other dsc debugfs enteries into
> one as a cleanup task later. But it will impact IGT aswell. And i'm not
> sure if we can break compatibility but since IGT (intel as only vendor)
> is the only consumer, may be we change at both places and clean it up.
We can do what we want with debugfs, as long as we change both the
driver and igt.
>
>>
>>> +
>>> +out:
>>> + drm_modeset_unlock(&dev->mode_config.connection_mutex);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static ssize_t i915_dsc_fractional_bpp_write(struct file *file,
>>> + const char __user *ubuf,
>>> + size_t len, loff_t *offp)
>>> +{
>>> + struct drm_connector *connector =
>>> + ((struct seq_file *)file->private_data)->private;
>>
>> I know this is copy-pasted from elsewhere, but really it's nicer to
>> avoid the cast, and copy-paste from the places that get this right:
>>
>> struct seq_file *m = file->private_data;
>> struct drm_connector *connector = m->private;
>
> Done.
>
>>
>>> + struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
>>> + struct drm_i915_private *i915 = to_i915(encoder->base.dev);
>>> + struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>>> + bool dsc_fractional_bpp_enable = false;
>>> + int ret;
>>> +
>>> + if (len == 0)
>>> + return 0;
>>
>> kstrtobool_from_user() has this covered.
>
> Done.
>
>>
>>> +
>>> + drm_dbg(&i915->drm,
>>> + "Copied %zu bytes from user to force fractional bpp for DSC\n", len);
>>
>> That's useless.
>
> Done.
>
>>
>>> +
>>> + ret = kstrtobool_from_user(ubuf, len, &dsc_fractional_bpp_enable);
>>> + if (ret < 0)
>>> + return ret;
>>> +
>>> + drm_dbg(&i915->drm, "Got %s for DSC Fractional BPP Enable\n",
>>> + (dsc_fractional_bpp_enable) ? "true" : "false");
>>
>> Is this useful?
>
> Yes, to know when fractional bpp is enabled.
I think it would be more useful to debug log this at the use site, not
when you're setting the debugfs knob.
BR,
Jani.
>
>>
>>> + intel_dp->force_dsc_fractional_bpp_en = dsc_fractional_bpp_enable;
>>> +
>>> + *offp += len;
>>> +
>>> + return len;
>>> +}
>>> +
>>> +static int i915_dsc_fractional_bpp_open(struct inode *inode,
>>> + struct file *file)
>>> +{
>>> + return single_open(file, i915_dsc_fractional_bpp_show, inode->i_private);
>>> +}
>>> +
>>> +static const struct file_operations i915_dsc_fractional_bpp_fops = {
>>> + .owner = THIS_MODULE,
>>> + .open = i915_dsc_fractional_bpp_open,
>>> + .read = seq_read,
>>> + .llseek = seq_lseek,
>>> + .release = single_release,
>>> + .write = i915_dsc_fractional_bpp_write
>>> +};
>>> +
>>> /*
>>> * Returns the Current CRTC's bpc.
>>> * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
>>> @@ -1513,6 +1593,9 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
>>>
>>> debugfs_create_file("i915_dsc_output_format", 0644, root,
>>> connector, &i915_dsc_output_format_fops);
>>> +
>>> + debugfs_create_file("i915_dsc_fractional_bpp", 0644, root,
>>> + connector, &i915_dsc_fractional_bpp_fops);
>>> }
>>>
>>> if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
>>> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
>>> index 69bcabec4a29..27b31cb4c7b4 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>>> @@ -1797,6 +1797,7 @@ struct intel_dp {
>>> /* Display stream compression testing */
>>> bool force_dsc_en;
>>> int force_dsc_output_format;
>>> + bool force_dsc_fractional_bpp_en;
>>> int force_dsc_bpc;
>>>
>>> bool hobl_failed;
>>
--
Jani Nikula, Intel
